Jeez, another electrical question

[Michael Weber]

Pictured is the electrical panel in my garage of the house we purchased some months ago. I added a single 220 breaker for my compressor and a vfd to as yet unbuilt dc with 3 phase motor. The power to both go to separate fused shut off boxes. I added the grounds to where the existing grounds and neutrals were. Now, I'm thinking maybe the neutrals and grounds should be seperated? There is a separate ground bar on the opposite side of the box. Just want to keep things safe although this has probably existed for many years. Thanks.

[David G Baker]

Michael,
If this box is a sub panel the neutral and ground must be separated. If it is the main house panel the neutral and ground must be joined.
I am curious about all of the wires coming out of individual breakers. Not sure that this is correct. Another thing, the number of white wires attached to breakers???? The image isn't large enough for me to make out all of the details in the breaker box.
If it was my breaker box I would replace the box with one that has many more breakers with the current rating of the circuits I needed.

[Michael Weber]

Thanks David. It is a subpanel and may be a subpanel off another subpanel which is up in the attic. Don't have it all figured out yet. Not sure if this one is feeding the one in the attic or the opposite. It's a bit of a mess and a previous owner has used two conductor w/ground for 220 volt circuits with the bare ground attached to the neutral/ground bar. Not sure thats legal. That explains the white wires coming off the breakers.

[Bill Houghton]

Thanks David. It is a subpanel and may be a subpanel off another subpanel which is up in the attic. Don't have it all figured out yet. Not sure if this one is feeding the one in the attic or the opposite. It's a bit of a mess and a previous owner has used two conductor w/ground for 220 volt circuits with the bare ground attached to the neutral/ground bar. Not sure thats legal. That explains the white wires coming off the breakers.

If the subpanels are properly set up, you can tell which is upstream by turning off the breaker servicing the panel - that is, there should be a breaker which cuts off current to the subpanel. Ideally, there will be two: one in the upstream subpanel, to cut off all current exiting the box toward the secondary (downstream) subpanel; and one serving as a main breaker in the secondary subpanel. This seems unlikely in this layout, since there look to be several code violations there, but I hope you'll find there's at least one (in either subpanel). Look for the breaker(s) with the biggest wires, and turn off those breakers; then check to see which circuits are turned off.

As David Baker mentioned, the neutral and ground are bonded (attached to the same bus bar) at the main panel ONLY, and separate at every subpanel. You can buy add-on isolated neutral bus bars, though a lot of panels will come with them already installed; the ground bus bar, if I recall correctly, is bonded to your panel (to provide an equipment ground on the panel itself). I wonder what that object is in the bottom left of the subpanel in your picture.

From the picture, it's hard to tell whether there are mixed wires going to the bus bar at the right side. Clearly, there are some white (neutral) wires going there, although it seems like far more than make sense.

If the 220 circuits involved are pure 220 - no part of the circuit is providing 120 current - then I believe using 2 wire plus ground NM is OK for a 220 circuit, with the bare ground wire serving as the equipment ground. It's good practice, though, to wrap black or red tape around the white wire at both ends, to signal that it's carrying a hot leg, not a neutral leg.

Go to your local public library, and check out at least one book on basic electrical practice. Fine Homebuilding has published some good ones, but there are other good sources too. If there are several choices, lean toward the book with the newest copyright date (codes change), but check all of them out. You need a comprehensive understanding of residential electrical practice in order to tackle what looks like a rat's nest of problems.

In my opinion, residential electrical stuff's not hard - there are a limited number of rules, and anyone who can use basic tools carefully and can distinguish black, white, red, and green can do the basic steps.

It does require several abilities:

1. The ability to look at a problem and reason logically. This can be assisted by sitting down and drawing out the problem and the solutions. When we bought our hot tub years ago, I quickly found that the previous owner (or a well-intentioned friend) had used far too small a relay for the controls and had bollixed up the layout pretty badly. It took me a full afternoon to sit down and draw a proper schematic, but, by the end of the afternoon, I understood exactly how it worked, and have maintained it effectively now for 20 years.

2. The ability to learn by reading. In my opinion, electrical work is among the most intellectual of all the building trades (although nowadays, with green building finally coming into its own, all the trades require a good deal of book learning-type intellectual power). While the basic rules are simple, there are lots of subtle things, like not overstuffing boxes, that are logically obvious once you read them, but not intuitively obvious if you're sitting there, staring at the wires.

3. The ability to use basic tools with care and an obsessive concern for perfection in the work.

4. An equally obsessive desire to live a long time and die from something other than being electrocuted after taking a shortcut to save some money or time. In my stupid youth, I used to work circuits "live," because it was macho. I'm still stupid, but not that way anymore. When I'm working on something electrical, I'll check three times to make sure the circuit is off before proceeding, and I'll use my test equipment to confirm it, even if I KNOW that the circuit breaker I just turned off (and then checked twice that it was turned off) serves the circuit involved. I don't have grandchildren yet, and, if my sons ever get around to procreating, I really want to be around to play with the grandkids.

If you can't honestly say that you've got these capabilities, DON'T mess with these panels. If you feel you've got them, but are uncertain as to what you're finding, you might check around your neighborhood or amongst your friends and see if there's a competent electrician who can inspect what you've got and give you some advice. A couple of hundred dollars to get a good handle on what you've got could save you grief, time, and money. Much as this community will want to help, only so much can be done with pictures on the Internet.

[Michael Weber]

Thanks Bill. I think what you see in the lower left of the box is the ungrounded bus bar which I assume would be for neutrals. There are no wires attached to it at all. In fact, all the 115 volt circuits to all the outlets have both the ground and white wire to the grounded bus bar. Also it appears this box is being fed from the other subpanel. The upper right breaker is the main breaker for the box and is 60 amps and the wire is about 10 or 8 gauge stranded. It is two conductor plus ground with the ground wire going to the common bus bar.

[David Meade]

In fact, all the 115 volt circuits to all the outlets have both the ground and white wire to the grounded bus bar.

This is a serious flaw and must be attended to right away, Your electrical system is dangerous, your house is not protected. This has potential to place any metalic object in your house in association with the wiring to become live. This also negates the safety ground system. Have this looked at right away.

[Michael Weber]

Thanks David. It seems Bozo the clown might have done the wiring. This subpanel and the one that feeds it are in a detached building consisting of two double garages (one of which is the shop) and a small apartment (unrented) above one of the garages. In addition to all the mentioned problems it seems on closer inspection that someone has provided 220 volts to an air conditioning circuit in the apartment using two single pole breakers. There is a red wire on one and black on the other. The white wire goes to the grounded bus bar and the ground wire is clipped off! You would have thought the home inspector might have caught some of this.

[Tom Veatch]

...a previous owner has used two conductor w/ground for 220 volt circuits with the bare ground attached to the neutral/ground bar. Not sure thats legal. ....

Yes, that's not only legal, it's the normal way to wire a 240v circuit using NMC. The white wire should be marked at all accessible locations to show that it's not a neutral conductor - colored tape, heatshrink tube, or whatever the local jurisdiction requires. The bare goes to whatever bus is used for the EGC.

[Bill Houghton]

You would have thought the home inspector might have caught some of this.

Depending on the laws in your state, you may be able to get some relief either from the seller or from the home inspector. Even from the little photo you posted, it was obvious to several of us that there were issues (not all of us being electricians, either).

It would be nice for you if you could have the major safety issues addressed by a licensed electrician at no cost to you. You might look into what obligations the seller and/or home inspector have in this matter.

[Michael Weber]

Thanks Bill and Tom. I may look into seller/inspector liability but I live in Arkansas and it's not likely there is much recourse there. I'm going to go into the attic and check out the other sub panel and see what it looks like with the cover off. I'm guessing it was an earlier addition since it is on the original garage structure so it may be in better shape. After that, I plan to move the 115 volt neutrals over to the neutral bar. I am under the impression that is the only real pressing need since it seems the 220 volt stuff is okay with the exception of the white wires not being marked as not being actual neutrals. The house by the way is about 100 years old. Most of the electrical has been upgraded from the original knob and tube although some of it still exists.

[Roger Frazee]

Thanks David. It seems Bozo the clown might have done the wiring. This subpanel and the one that feeds it are in a detached building consisting of two double garages (one of which is the shop) and a small apartment (unrented) above one of the garages. In addition to all the mentioned problems it seems on closer inspection that someone has provided 220 volts to an air conditioning circuit in the apartment using two single pole breakers. There is a red wire on one and black on the other. The white wire goes to the grounded bus bar and the ground wire is clipped off! You would have thought the home inspector might have caught some of this.

Hi Mike

I'm just going to go through a few problems I see (BTW I am an electrician). I don't see anything that is going to electrocute you unless you would have a feeder neutral open. Starting with the backfed breaker being used as the main in the upper right. It is fed with a cable that has black, white and a bare equipment ground and I don't see a hold down kit on the breaker (required for a back fed main breaker). At anyrate the cable should be a different type with two hot conductors a neutral and an equipment ground. The reason it needs to be a four wire feeder to both sub-panels (I'm assuming both subpanels are getting there supply from the house) is because 3 wire feeders to sub-panels in detached buildings that also have a metal water pipe run to them from the house or any metallic path for that matter must be 4 wire. That would seem feasible since there is an apartment out there...:D

The next thing is the terminal strip on the left is your grounded neutral/ground bar not ungrounded. I can't see it but it should be set on insulated standoffs keeping it out of contact with the metal of the panel. And it should have the neutral of the feeder from the other sub-panel upstream connected to it. There should also be a green bonding screw through that terminal strip and threaded into the metal of the panel... bonding the neutral and ground. This needs to be done for all three wire feeders like you have at present. doing this allows you to connect both neutral and ground to that bar on the left just like you see over at the bar on the right, except that terminal strip on the right is a grounding bar only and should have no white or grounded conductors connected to it....only equipment grounds. I can't tell if they connected the neutral of the feeder to that bar or not...if they did it is incorrect. It should be on the bar on the left along with all the other white grounded conductors. If the feeder neutral is connected to the bar on the left then as things are now neutral current is using the metal of the panel to get to the feeder neutral to return to the transformer. Looking at this mess I believe the guy that wired this put so many wires in the left hand gutter that he decided to use that grounding bar on the right for all the ground and grounded connections. But I'm not sure which bar he connected the feeder neutral. And speaking of feeder neutral the cable he used as the feeder requires the white wire to be the neutral and he used it for a hot (ungrounded) conductor and the bare equipment ground is being used as the neutral....not supposed to be that way...:D

So I can tell you this much the feeder to this sub-panel and likely the other are going to need to be changed to 4 wire feeders because of the water line (if metal) and any other metallic paths like phone or data that have been run from the house to this detached building.

I'm sorry if this is confusing I just don't know how else to go it any simpler.

There are much better panels than what you have and I would recommend changing the one you show to a 100 amp panel with more spaces to accomodate all those circuits.
Finally if this is the down stream sub panel you need to investigate the sub-panel ahead of this one and make sure there is a disconnect for the building in that panel (main breaker) or some sort of disconnect close to where the feeder from the house enters your detached building.

Finally, finally if you want to correct the existing panels we can tell you how to do that until you get 4 wire feeders and panel upgrades.

[Michael Weber]

Roger, thanks for taking time to explain. I just got back from inspecting the upstream sub panel. There are 3 large wires into it from the house (not four). All the bare wires and all the white wires in this box are attached to the neutral bar along with the incoming neutral. So, the bare wire for the downstream box is serving as a neutral but is going to the equipment ground bus bar in the downstream box where all the other grounds and neutrals are! I do know the apartment has it's own water supply (from my irrigation meter:eek:) so having 3 wires may not be an issue as far as electrical is concerned. Aren't old houses wonderful? BTW I'm not planning on renting the apartment(especially now). It's small, uninsulated and ugly inside and it makes a good storage place although upstairs.

[Roger Frazee]

Mike

Your welcome. Yeah I was wondering if maybe it had its own water supply. If you move those white neutrals and the feeder neutral over to that terminal strip on the left (you should do that) be real sure that the terminal strip on the left has the green screw through it to bond the bar to the metal of the panel because it should be sitting on insulated stand offs.. If you can do that you could if you want move the bare equipment grounds over to it also. But ya got a lot of wires to negotiate to get to the terminations on the neutral bar on the left. If the grounds are not long enough just leave them on that grounding bar.

[Michael Weber]

Thanks again Roger. One question. If the neutral bus bar is supposed to be bonded to the metal of the box whats the difference between it and the already grounded equipment ground bus on the right? Won't they be shorted together? Would be nice to clean this all up. May contact an electrician next week to make sure it gets done properly and have the two boxes replaced with a single bigger box.

[Roger Frazee]

Hi Mike

The neutral bar on the left should be on insulated stand offs.... And bonded to the metal of the panel if the panel has a three wire feeder. If a hot wire comes in contact with the metal of the panel the fault current will travel to the bonding jumper (green screw) to the neutral bar out the feeder neutral all the way to the service equipment (house main breaker panel) out the service neutral to the center tap of the transformer. This low impedance/resistance path facilitates massive current flow and trips out the circuit breaker. If that bonding jumper (green screw) isn't installed then there is no path to the neutral conductor of the feeder and the metal will come to line voltage and no breaker will trip. touch the metal and you get zapped.

Now to answer your question. At present you have the feeder neutral connected to the grounding bar on the right. In reality this is pretty much the same as having everything connected to the neutral bar on the left with the main bonding screw installed only because you have a 3 wire feeder. Panelboards are required in residential load centers to have the ability for the neutral and ground to be isolated in non service equipment applications....like sub panels with 4 wire feeders. Therefore they set the neutral bar on insulators so that the green screw or what ever is used as the main bonding jumper can be removed and effectively allow the neutral to be isolated from ground.
So you don't have a big safety issue with the way your panel is now other than that bar on the right appears to be an add on and may not be bonded to that box with factory mounting screws using factory predrilled holes. So other than an iffy bond to the panel there isn't much difference.

But if you will lets wire the panel as it should be. Move the feeder neutral over to the terminal strip on the left and install the green screw bonding the neutral bar to the metal of the panel but leave the neutrals and grounds of the branch circuits connected to the grounding bar on the right. Now all branch circuit neutral current from 120 volt loads must use the metal of the panel to get to the green screw then to the feeder neutral to return to the service equipment and back to the transformer. You do not want neutral current flowing on the metal of the panel. You only want fault current using bonded metal because that current is only there for as long as it takes to trip a circuit breaker. I posted a diagram below to show the problem when we connect grounded conductors to a grounding bar in a panel with a 3 wire feeder with the neutral bonded to ground. Note also that if we remove the bonding jumper the neutral and fault current path will open between the grounding bar and the neutral bar. If any hot phase faults from branch circuits occur to the metal of the panel then a breaker will not trip, the metal will come to line voltage or neutral current will load the panel waiting for a path to the transformer. It will use you if no other lower impedance path exists. The danger in this that the 120 volt loads whose neutrals are connected to the ground bar will stop working so you investigate and go over to the panel.. touch the metal.. at that point if the right conditions exist you could recieve a fatal shock. If there is a hot phase fault to the panel metal you will certainly recieve a shock because a breaker won't clear the fault..even if you have a ground rod connected to that ground bar. So you have two issues that can be deadly. I've also included a diagram showing the effective fault path for a ground fault in order for a breaker to trip just to give you an idea of how this all works. Just remember that current always seeks its source (the transformer) it will use every path available to it to get there. However if given a lower impedance/resistance path it will disproportionately take that path. If the low impedance path through bonded metal and ground wires and the neutral getting back to the transformer is taken away... current will use you, the earth or whatever to get back to the source.

EDIT: I suppose I should add that panels that have the neutral bar permanently bonded to the panel metal are panels that are to be used only as service equipment and not sub-panels. So I suppose if we get technical your sub-panel configured as it is presently is suitable for service equipment only because there is no way to seperate neutral from ground electrically without using the other terminal strip on the left assuming it is set on insulators.

Service Equipment: Panels or enclosures that house the first means of disconnect for a service. Neutral and ground are bonded here so fault or neutral current can utilize the low resistance/impedance of the service neutral to return to the transformer (center tap). This keeps current from seeking other paths available at the service equipment to get to the transformer in any appreciable amperage. For example in the diagram showing the effective fault path. There are connections to water pipes and supplemental electrodes like ground rods at the bonded neutral bar. If I have a poor connection to the service neutral causing high resistance or a failing service neutral (damaged overhead for example) more current that expected will seek the transformer through these other higher impedance/resistance paths. If you look at the diagram one path is for current to travel to the ground rod through the earth over to the transformer ground rod then to the center tap of the transformer. Another is the metal water pipe bond.

I apologize for getting a little carried away with this thread but it is critical to me that when DIY are working on their electrical panels that they understand this bonding and grounding so they know the why of what they are doing.

Carry on Mike

[Rick Christopherson]

Thanks Bill. I think what you see in the lower left of the box is the ungrounded bus bar which I assume would be for neutrals. There are no wires attached to it at all. In fact, all the 115 volt circuits to all the outlets have both the ground and white wire to the grounded bus bar. Also it appears this box is being fed from the other subpanel. The upper right breaker is the main breaker for the box and is 60 amps and the wire is about 10 or 8 gauge stranded. It is two conductor plus ground with the ground wire going to the common bus bar.When you first asked your question, I stayed out of the discussion because it appeared that from the information we had (at the time), it should have been a simple 2-sentence reply. However, you have received several convoluted responses that are misleading at best, and depending on how they are read are actually quite dangerous.

After re-reading the whole thread, I decided to take the time to bring your picture into photoshop so I could see a little more detail. (Although I still cannot make out all of the detail.)

First and foremost, this is a 240 volt subpanel, which does not have 120 volts available because there is no neutral conductor. The original installation was correct for its purpose, but over time, someone has added single-pole (120 volt) circuits to the panel. These need to be removed. This is the reason why the left-hand bus terminal was not used.

Take a closer look at the incoming feeder. From the picture, it looks like 10/2 romex, but admittedly, they could be larger than they appear.

This panel is correctly wired for 240-volt usage (after you remove the 120 volt circuits). However, if you do need this subpanel to provide 120/240 volt circuits, then you must use a new feeder cable with 3 insulated conductors, and preferrably a ground, but since this is a detached building, that may or may not be required (we don't know enough about this building, so when in doubt, run the ground.)
I'm just going to go through a few problems I see (BTW I am an electrician).Roger, because you prefaced your first posting by stating you were an electrician, I am going to take you to task for the advise you presented. When you state your credentials, it puts you in a position of authority and knowledge, and as such, holds you to a higher level of responsibility than a typical respondent.

As an electrician, you should not have advised Michael to use the uninsulated grounding conductor in lieu of the neutral (grounded conductor) and treat this as a 3-wire feed by installing a bonding screw into a neutral bus. This violates the NEC on so many levels, I shouldn't have to point this out to you. Not only is it prohibited to have any current carrying conductor be uninsulated, but the ground wire in a typical romex cable is not sized properly for the circuit protection from which it is being served.

[Rick Christopherson]

By the way Michael, I also noticed that at least the upper-left 2-pole breaker has multiple wires going to the lugs. Most circuit breaker lugs are not rated for more than a single wire. Unless this is one of the rare exceptions (which I doubt), then you should pull these circuits out.

[Roger Frazee]

And speaking of feeder neutral the cable he used as the feeder requires the white wire to be the neutral and he used it for a hot (ungrounded) conductor and the bare equipment ground is being used as the neutral....not supposed to be that way...:D
With all due respect Rick I think you need to reread my responses about the cable with the bare equipment ground serving as the neutral for the feeder because of the 120 volt load. I told him this was the wrong cable to be used....:D Because of the bare neutral being an equipment ground.. And that the panel should be replaced and that the cable should be replaced and that he should upgrade the panels and feeders. I told him we could get the panels better configured until he could effect the necessary repairs. A bare neutral is quite fine by the way if the detached building is served by overhead on 3 wires. Allowed under 2005 and when this installation was first installed assuming no other metallic paths other than the feeder from the service equipment at the house.. It could be that I confused things for that I apologize but what is going on in that panel and the installation as a whole is not simple. The panel is not 240 volt as configured it is 120/240 volt though incorrectly done.

The simple answer is he needs to bring this all up to code... I do believe he has made mention of this several times.


As an electrician, you should not have advised Michael to use the uninsulated grounding conductor in lieu of the neutral (grounded conductor) and treat this as a 3-wire feed by installing a bonding screw into a neutral bus. This violates the NEC on so many levels, I shouldn't have to point this out to you. Not only is it prohibited to have any current carrying conductor be uninsulated, but the ground wire in a typical romex cable is not sized properly for the circuit protection from which it is being served.

Its being used as that now though incorrectly... And what if the cable he used was SE type from panel to panel? Perfectly legal for the neutral to be bare enclosed within a outer sheath if the 3 wire feed to the detached building was code compliant which we have verified it was now and at the time of installation. Phone and water are not connected to the dwelling with the service equipment which supplies the feeder to this detached building.... As for the nm which I told him was incorrect for the reasons you stated ...I even gave him a defined description of why that feeder cable was incorrect. As for the bare in that nm cable being in danger of overheating I doubt it. The whole installation needs to be fixed.. I thought that was what all this discussion was about. As for telling him to continue to use the bare equipment ground in that nm cable till he gets things fixed...I still stand by that knowing that he now understands it needs to be replaced. I refuse to tell him to turn off all the power to his detached building cause he is in terrible danger of burning his shop down. He is not. I think he has understood from the beginning that he has a few problems.


First and foremost, this is a 240 volt subpanel, which does not have 120 volts available because there is no neutral conductor. The original installation was correct for its purpose, but over time, someone has added single-pole (120 volt) circuits to the panel. These need to be removed. This is the reason why the left-hand bus terminal was not used.

Possibly but he could have configured it the same way with the other terminal strip on the left using the bonding jumper. Mike stated that two of the single poles are used for a 240 volt circuit to an air conditioner..so that leaves only one 120 volt circuit. But it appears that there are at least 3 grounded conductors on that ground bar so obviously something is amiss. However your analysis that the panel might have been intended for 240 volts only is quite possible. I didn't consider that.

I told him I would tell him how to change the configuration of that panel because I think it serves a marginal safety improvement over what he has now until he effects repairs as mentioned.

He expressed an interest to understand what he has so I made an effort to do that.

Sorry if you don't agree.

However I will concede further long discussions on this forum as I continue to respond here. It seems we prefer the simple.

BTW the actual reason that 5 hp saw in that other thread is not allowed cord and plug is it requires a 5 HP rated single phase 250 volt plug and receptacle required in Article 422 and Article 430 and Article 210....but we kept it simple. No such animal exists in locking or straight blade nema configurations. You can verify this if you like in the UL White Book...the manufacturers are well aware of this...they are not a notoriously wrong as you implied. Robs 7.5 horse power 3 phase equipment has the ability to have cords and plugs rated to that horsepower. Just to further confuse things...;)

[Michael Weber]

Hi Mike

I apologize for getting a little carried away with this thread but it is critical to me that when DIY are working on their electrical panels that they understand this bonding and grounding so they know the why of what they are doing.

Carry on Mike

Roger, no apologies necessary. Your time to reply and the information provided is greatly appreciated. I believe it will be in my best interest to hire an electrician to update my system and replace the dual subpanels with a properly sized single box.

Thanks again, Mike

[Michael Weber]

By the way Michael, I also noticed that at least the upper-left 2-pole breaker has multiple wires going to the lugs. Most circuit breaker lugs are not rated for more than a single wire. Unless this is one of the rare exceptions (which I doubt), then you should pull these circuits out.

Thanks for the input Rick. The upper left breaker problem is on me:p. That is the circuit I added to provide power for my compressor and a vfd. The two sets of wires from this single breaker go to different fused shut off boxes and by now I am sure this also violates code. See my response to Roger about getting hold of an electrician to bring all this up to specs. Yours and Rogers input is greatly appreciated.
Mike

[Roger Frazee]

No problem Mike

And yes an electrician is in order.

Have a great day

[Alan Trout]

Not trying stir the pot but just want to make a few comments about the panel in question. Being a Professional Home Inspector there are many issues noted with that panel but in reality not enough information or clear enough photo is present for anyone to make a clear determination including myself and I suggest that you hire a licensed electrician to make corrections as needed.

First I would like to comment about telling someone to go after the home inspector. These comments always bother me on a professional level. This advice may be valid or not. Remember inspectors in most states are not inspecting for present codes, and latent defects most times are not within the scope of the inspection. However I personally do list these things in my report more as a note for understanding construction practices at the time the home was built and how they relate to current building practices. However if the home was inspected and and the items such as double lugged breakers were not listed in the report I would call the inspector and find out why these items were not noted. These kind of items fall well within the scope of most home inspections.

Isolated grounds and neutrals at sub panels did not come into being until about the 1976/1978. Before that time neutrals and grounds shared the same bus bar in sub panels. I am not saying it is right I am just saying that the reality is 30 year old house will not meet present electrical codes and in many/most municipalities they don't have to be brought up to current codes. If that were the case every one of us should start installing AFCI protection because in the 2008 NEC all circuits in a home besides the GFCI protected circuits are required to have AFCI protection.

There is so much liability in this world these day's I am always hesitant to make any electrical recommendations to anyone and more often then not give referral back to a licensed electrician, which in the case is the best solution.

Good Luck

Alan

[Rick Christopherson]

No, Roger, I did read your response carefully. And even though you suggested that the wiring was not correct in the beginning of the response, you went on at greater length telling him that he could correct it by using the ground wire as a neutral. The incoming cable is clearly romex, and in the larger sizes of romex, the ground wire is not large enough to be used as a neutral. Furthermore, you have since compounded your error by suggesting that a configuration that he clearly doesn't have might permit an uninsulated neutral.

When you make a mistake, accept responsibility for it instead of trying to sidestep it.
BTW the actual reason that 5 hp saw in that other thread is not allowed cord and plug is it requires a 5 HP rated single phase 250 volt plug and receptacle ...... No such animal exists in locking or straight blade nema configurations. I do not pay much attention to who's-who on the forums, so I had no idea you were the same person making this previous statement. However, if you were more up to date on your information, you would know that there are plugs and receptacles far larger than 5 hp. I happen to have a plug and receptacle sitting in my basement that is capable of handling a 52 KVA load. That's a wee-bit larger than 5 hp, right?

[Roger Frazee]

No, Roger, I did read your response carefully. And even though you suggested that the wiring was not correct in the beginning of the response, you went on at greater length telling him that he could correct it by using the ground wire as a neutral. The incoming cable is clearly romex, and in the larger sizes of romex, the ground wire is not large enough to be used as a neutral. Furthermore, you have since compounded your error by suggesting that a configuration that he clearly doesn't have might permit an uninsulated neutral.

When you make a mistake, accept responsibility for it instead of trying to sidestep it.I do not pay much attention to who's-who on the forums, so I had no idea you were the same person making this previous statement. However, if you were more up to date on your information, you would know that there are plugs and receptacles far larger than 5 hp. I happen to have a plug and receptacle sitting in my basement that is capable of handling a 52 KVA load. That's a wee-bit larger than 5 hp, right?

Rick

Again with all due respect those plugs are specialized plugs and are not in the nema locking or straight blade design and are not generally used for connecting 5 horsepower saws...to household supplies. Did you suggest that in the thread.....

I did not tell him to correct the problem by moving the bare feeder neutral over to the left neutral bar. I told him he could do so for the time being until he could get it done right, he understood this... you missed it. It would have been very wrong to tell him to move the configuration to the left neutral bar and forget it... all is fine. That was not my intention and if that is how things appeared to you I can only say that was a misinterpretation of my advice.

As for this thread.. it's a done deal. The cable needs to be replaced. I do not agree that he has to remove his 120 breakers. I would only do this if my mother in law had life support on one of those 120 volt breakers....;)Turn them off maybe but he does not have enough unbalanced current to overload his feeder neutral as wrong as it may be. Moving it to the left hand neutral bar changes nothing and configuring things from there makes it more understandable to most. My suggestion was merely temporary, if it was poor judgement or wrong my error.

[George Lohnes]

Michael forgot to mention in his original post that this electrical connection was for an underpowered dust collector leading to the Festool tools on top of his Sawstop. :eek:

[things seem to be quieting down on the post and just thought I could heat things up some more] :D

[Tom Veatch]

...the actual reason that 5 hp saw in that other thread is not allowed cord and plug is it requires a 5 HP rated single phase 250 volt plug and receptacle ...

Roger, please pardon my ignorance and understand that I'm not trying to challenge what you say. I'm simply trying to improve my understanding.

Following comments are based on my understandings, and I would certainly appreciate corrections where they fall short.

If a 5HP motor requires a 5HP rated plug and socket, by extension, would not a 3HP motor require a 3HP rated plug and socket? Or, for that matter, would not any plug and socket used for a motor load need to be rated for the HP of the motor? The reason I ask is because I do not recall ever seeing plugs and sockets rated for anything other than volts and amps and I've seen no negative comments regarding using power cords/plugs/sockets for 3HP and smaller motor loads.

I understand that switching devices need to be rated for the HP of the motors they control because of the inductive nature of the load and the voltage spikes and/or arcing that occurs when the switch is actuated. But unlike switches, contactors, etc., plugs and sockets are static devices and aren't intended to be used to make/break a circuit. Thus they aren't subject to the same conditions as switches, etc.

After reading your comment concerning 5HP rated plugs and sockets, I made a fast, admittedly incomplete, search of various manufacturers web sites looking for receptacles that were rated for HP in addition to volt/amps. I didn't find any. I found NEMA 6 and L6 devices in both 20 and 30 amp ratings, none of which were rated by the manufacturer in terms of power. Not saying they aren't out there, just that I didn't find any.

I've previously had no qualms about using a 6-20/L6-20 device on a power cord for a 3HP motor (20 amp circuit) and by extension, would have had no qualms about using 6-30/L6-30 devices for a 5HP motor on a 30 amp circuit. In the absence of power rating on the devices, I see no substantiative difference between the two cases.

For any readers not familiar with the designations, NEMA 6/L6 devices are 250 volt 2-pole, 3-wire, grounding devices - IOW, 250 volt single phase grounding plugs and receptacles.

[Chris Padilla]

Tom,

Well, aren't those plugs rates at, for example, 30 A @ 250 V? 30*250 = 7,500 W =~ 10 hp?

Is it that simple?

[Roger Frazee]

Tom

Any motor or motor appliance needs to have a matching hp rated plug this generally is a result of disconnect issues under load. By that I mean a plug and receptacle is allowed to be the disconnecting means only if it is rated the same as the motor in horse power. You get into problems with nema plugs for single phase 250 volt 2 pole 3 wire grounding above 3 horse power. Personally I agree there isn't likely to be any problem with 2 or 3 hp on a L6_20. Maybe not even with 5 hp I don't assume to be an expert on this. IMO the manufacturer is not allowing cord and plug or extension cords on the 5 hp sawstop because there is no 5 hp nema configuration for that saw . Can you get 5 hp plugs... sure.. but these are specialized plugs and not typical for general use for cord and plug tools and likey not configured for the voltage we are talking about. I could be wrong on this...Rick seems to think so.

At anyrate here is the UL list of corresponding hp ratings for cord and plug. If you call sawstop I think you will likely get the reasoning I have discussed as to why their manual says NO cord and plug. Do I think there is a great issue one way or the other....must not be as everyone here seems to be doing fine with their saws on cord and plug :). I am simply trying to answer why a 5 hp saw 230 volt single phase like the sawstop is not allowed cord and plug by the manufacturer. You may have to click on it a few times for it to be readable.

[Tom Veatch]

Tom,

Well, aren't those plugs rates at, for example, 30 A @ 250 V? 30*250 = 7,500 W =~ 10 hp?

Is it that simple?

Chris, I really don't know when you get into the plug/receptacle area.

If you look at switching devices, those intended for motor control are rated both in amps and in power (HP) at a given voltage. Typically, the HP rating is the more restrictive of the two. I.E, if you take the volt/amp rating of the switch and convert to the equivalent HP (volt*amps/746), the result is greater than the switch's HP rating. In effect, the device is "derated" for motor loads.

For an example, take the Leviton MS302 (http://www.leviton.com/OA_HTML/ibeCCtpItmDspRte.jsp?item=12284&section=10042) motor control switch. It's a double pole switch rated for 600 volts and 30 amps. It's power rating is 2HP-120V, 5HP-240V, 10HP-480V, 15HP-600V. Converting the 30 amp rating at those voltages gives the respective HP values: 4.8, 9.7, 19.3, 24.1. Those calculated values are all much higher than the actual power rating of the switch.

I've always assumed, rightly or wrongly, that's because of the inductive nature of a motor load. When you break the circuit feeding an inductive load, e.g. a motor, the collapse of the magnetic field in the coils induces a voltage spike that you don't see when you break a circuit feeding a resistive load. Again, my assumption has been that's the reason for "derating" the switching device. Since plug/receptacle devices aren't typically intended to be used as disconnects under load, my assumption has been that separate HP/inductive load ratings really aren't appropriate. If that assumption is correct, then the answer to your question is, "Yes, it is just that simple".

But, that is just my assumption supported by never having seen a power rating on plugs/receptacles separate from or in addition to the normal volt/amp ratings. And you know what they say about "ass-u-me".

[Tom Veatch]

...Any motor or motor appliance needs to have a matching hp rated plug this generally is a result of disconnect issues under load. By that I mean a plug and receptacle is allowed to be the disconnecting means only if it is rated the same as the motor in horse power. You get into problems with nema plugs for single phase 250 volt 2 pole 3 wire grounding above 3 horse power. ...

Thank you, Roger. That chart is an eye-opener. I may just save that in my "wall-chart" folder.

I notice that you don't get up to the 3HP rating with 6/L6 devices until you hit the 50 amp level.:eek:

I assume from your comment on use as a disconnect there's no real problem involved in using a NEMA 6-20 plug/socket to feed a 3HP load as long as it's not used as a disconnect device. I'll have to remember not to unplug my 3HP table saw (NEMA 6-20, 2 HP L-L rating) while it's running.:)

Now, I'm understanding why the electrician ran the 30 amp circuits for my air compressor and cyclone to disconnects rather than to 30 amp receptacles (5HP motors hardwired to the disconnects in both cases).

Thanks, again.

[Roger Frazee]

Thank you, Roger. That chart is an eye-opener. I may just save that in my "wall-chart" folder.

I notice that you don't get up to the 3HP rating with 6/L6 devices until you hit the 50 amp level.:eek:

I assume from your comment on use as a disconnect there's no real problem involved in using a NEMA 6-20 plug/socket to feed a 3HP load as long as it's not used as a disconnect device. I'll have to remember not to unplug my 3HP table saw (NEMA 6-20, 2 HP L-L rating) while it's running.:)

Now, I'm understanding why the electrician ran the 30 amp circuits for my air compressor and cyclone to disconnects rather than to 30 amp receptacles (5HP motors hardwired to the disconnects in both cases).

Thanks, again.

Yes the issue is whether you intend to disconnect the motor or not with the plug. Problem is who knows if you might or might not. I'm not sure if I have the issue nailed down perfectly but I am reasonably confident that sawstop is indeed not intended to be used with a plug being on a individual branch circuit as required. If I wired it I would do as your electrician did and land permanent wiring from the saw to a wall mounted disconnect.

[Rick Christopherson]

The reason I ask is because I do not recall ever seeing plugs and sockets rated for anything other than volts and amps and I've seen no negative comments regarding using power cords/plugs/sockets for 3HP and smaller motor loads.Tom your gut instincts are correct. A sure sign that someone is professing knowledge beyond their means is when they cite entire chapters of the NEC and not individual citations. They do this because they know that no one is ever going to challenge it because no one will be willing to spend the time to review an entire chapter. Most days, that is a good bet.

Today is not a good day to make that bet. I have had a lot of sporatic down-time today waiting for floor adhesive to tack up between layings, and I did in fact read through the entire sections of the NEC that Roger cited. There is nothing in the NEC that supports Roger's assertions and citations. :mad:

I don't know what UL has to say on the topic, but I also don't care what they have to say either. UL is not a regulatory agency, and has absolutely no bearing on wiring a tool into a home receptacle. If need be, I have a copy of UL 987 on my computer, and I can look this information up--not that it would matter. No, this is not the "cliff-notes" version that Roger is citing; this is the full version that manufacturers need to purchase when they want their tool UL listed.

I need to go lay another batch of tile in the shop.

[Rick Christopherson]

Yes the issue is whether you intend to disconnect the motor or not with the plug. Problem is who knows if you might or might not. I'm not sure if I have the issue nailed down perfectly but I am reasonably confident that sawstop is indeed not intended to be used with a plug being on a individual branch circuit as required. If I wired it I would do as your electrician did and land permanent wiring from the saw to a wall mounted disconnect.I knew this was going to be the topic from NEC you would reference, and I did read this a couple hours ago. You need to go back and reread this part of code more carefully.

[Michael Weber]

Michael forgot to mention in his original post that this electrical connection was for an underpowered dust collector leading to the Festool tools on top of his Sawstop. :eek:

[things seem to be quieting down on the post and just thought I could heat things up some more] :D

While I don't have a saw stop or and Festool stuff, I do have an underpowered dust collector.:( Adding a circuit for a new dc system is what prompted the original question.
I think everything is cool now.;) Every ones input was taken with gratitude. Got some very informed information from highly qualified members and it was all helpful.
Thanks everyone. Mike

[Roger Frazee]

Tom your gut instincts are correct. A sure sign that someone is professing knowledge beyond their means is when they cite entire chapters of the NEC and not individual citations. They do this because they know that no one is ever going to challenge it because no one will be willing to spend the time to review an entire chapter. Most days, that is a good bet.

Today is not a good day to make that bet. I have had a lot of sporatic down-time today waiting for floor adhesive to tack up between layings, and I did in fact read through the entire sections of the NEC that Roger cited. There is nothing in the NEC that supports Roger's assertions and citations. :mad:

I don't know what UL has to say on the topic, but I also don't care what they have to say either. UL is not a regulatory agency, and has absolutely no bearing on wiring a tool into a home receptacle. If need be, I have a copy of UL 987 on my computer, and I can look this information up--not that it would matter. No, this is not the "cliff-notes" version that Roger is citing; this is the full version that manufacturers need to purchase when they want their tool UL listed.

I need to go lay another batch of tile in the shop.

Try to get some rest Rick. Article to 210.2 (refers you to table 210.2 then 430 IX) (Article 422.34 Unit switch as a disconnect) I mentioned this only if you want to classify the saw as a motor driven appliance and then NEC 430.109(F).

Remember this is all about why the manufacturer at sawstop is not allowing a 5 hp motor to be cord and plug on this saw. I believe it is because of disconnect issues. You say they are just stupid and I disagree. You say that UL is something that you would not believe because they are not regulatory yet the NEC certainly does. But you want to site UL 987 to void the UL white book table I listed. That same table you will find in your full blown version.

I have no problem with cord and plug on this saw, the discussion is about the manual not allowing it to be so. I am walking a mile out of my way to give argument as to why the manufacturer is likely correct. You chose to insult me and everyone is supposed to take your word for it. I don't answer to you. If you have some documetation that proves the manufacturer is wrong on this saw then provide argument with code or something.

I'll say this one last time I believe the manufactuerer is correct.. the saw should not be cord and plug. I may very well be eating crow in the end. I believe the manufacturer is protecting itself against using the cord and plug as a disconnecting means and backs that by the motor rules for cord and plug horsepower ratings for motor disconnects in 430.109(F). You have to take a stand somewhere right or wrong. But for you to state that manufacturers are notorious for wrong information is a stretch and middle of the road IMO. There is absolutely nothing wrong with wiring this saw under the rules of artcle 430.

I don't think it is necessary and looking at it as just connecting the saw with an L series 30 amp I see no reason why not. I am simply trying to answer what I think the manufacturers reasoning is for not allowing cord and plug for their 5 hp 230 volt single phase saw. You keep wanting to imply that I am saying you cannot cord and plug this saw. You cannot looking at it from a means of disconnect with a nema L series plug and receptacle. I beleive this is why the restriction by the manufacturer... simple as that. Get over it.

[Chris Padilla]

I think Rick and Roger can take a breather from this...I'd be happy to blow the froth off a couple with both ya'll and pick up the tab. :)

Happy Electron Flow! :D