Stupid Electrical Questions

[Brian Holcombe]

Good morning gents.

I am awaiting a MM20 saw and in my evening hours I have been wiring the shop for it, along with a dust collector. I'm running separate conduits for each tool and, of course, separate breakers.

From what I have read the MM20 comes wired for an L6-30 Twist lock outlet, so I bought that outlet.

Am I correct in my understanding that what I need for this are two hots (red and black) and a ground (3 wire). I'm running individual wires through conduit, using 10ga copper.

I ran my wire with the mistaken assumption that I needed 4 wires, and so I have a white wire in the run, which now I believe I can simply cap off.

Is it a safe assumption that all 240v single phase tools that I purchase will be 3 wire?

I don't wire often, so sometimes it takes me a little while to get my bearings, so thank you for any help offered.

[Marc Burt]

Yes that's a safe assumption. Generally (very generally) speaking the only time you'll need 4 wire is something that has 110v run as well, like a stove with a 220 oven and 110 clock etc.

Also no need to run separate conduit. Both circuits can go in the same conduit so long as you don't exceed the full rate for the size conduit. That said, you're a better man than me pulling 10 gauge. I cuss like a sailor whenever I pull 12.

[John K Jordan]

Is it a safe assumption that all 240v single phase tools that I purchase will be 3 wire?


I can't speak for "all" 240v tools but all I have are 3-wire, jointer, tablesaw, bandsaw, lathe, air compressor, cyclone, welders, plasma cutter.

I believe some appliances such as clothes dryers use 4-wires, one a neutral, in order to run internal 110v control circuits.

I do all my own wiring but I am not an electrician (except in Mexico).

JKJ

[Ben Rivel]

Yep, all the 220v power tools I have come across were two hots and a ground.

[Brian Holcombe]

Thanks gents, much appreciated!


Yes that's a safe assumption. Generally (very generally) speaking the only time you'll need 4 wire is something that has 110v run as well, like a stove with a 220 oven and 110 clock etc.

Also no need to run separate conduit. Both circuits can go in the same conduit so long as you don't exceed the full rate for the size conduit. That said, you're a better man than me pulling 10 gauge. I cuss like a sailor whenever I pull 12.

It was one of those situations, where on the surface it appeared very easy, in reality not so much! I bought tight 90's for the corners at my ceiling, ugh...not fun.

[Mike Heidrick]

Do enough 10, 12 is a breeze.

[Ryan Mooney]

Thanks gents, much appreciated!



It was one of those situations, where on the surface it appeared very easy, in reality not so much! I bought tight 90's for the corners at my ceiling, ugh...not fun.

For those the generally recommended solution is to use boxes at the 90s and do the pull in stages (don't cut the wire, just pull in stages).

In fact there is a limit on the number of bends that are technically allowed without a pull box.

How many bends are allowed in conduit?

NEC 346-11: “There shall be no more than the equivalent of four quarter bends (360 degrees total) between pull points, e.g., conduit bodies and boxes.” TIA/EIA-569, 4.4.2.1: “No section of conduit shall be longer than 30m (100ft) or contain more than two 90 degree bends between pull points or pull boxes.

[Prashun Patel]

Are you certain it comes pre-wired with a plug? I just checked an older manual that implies that the MM20 comes with a short cord and junction box.

[Brian Holcombe]

For those the generally recommended solution is to use boxes at the 90s and do the pull in stages (don't cut the wire, just pull in stages).

In fact there is a limit on the number of bends that are technically allowed without a pull box.

How many bends are allowed in conduit?

NEC 346-11: “There shall be no more than the equivalent of four quarter bends (360 degrees total) between pull points, e.g., conduit bodies and boxes.” TIA/EIA-569, 4.4.2.1: “No section of conduit shall be longer than 30m (100ft) or contain more than two 90 degree bends between pull points or pull boxes.

Thanks for posting that up! I've been using pull elbows, which apparently negate this, but all things considered I've still be attempting to minimize how many corners I have.


Are you certain it comes pre-wired with a plug? I just checked an older manual that implies that the MM20 comes with a short cord and junction box.

I plan to leave my connection unwired until the saw arrives, but I read posts from Erik Loza saying they use L6-30's. If that is not the case, then I will terminate the cord with an L6-30, so that I can break the connection with ease if need be, but it will otherwise lock into place.

[Prashun Patel]

What DC did you get? Congrats by the way on your MM purchase. I know you have been eyeing it for a while. Your resaw elbow will thank you ;) What blade did you purchase?

[Brian Holcombe]

Thank you! Haven't bought a DC yet, that will be soon and highest one on the list is V3000 from Oneida.

I bought a wood master CT 1" x 1.3T, and some sort of general use lenox bi-metal blade in 1" x 3t

I have a pile of wood waiting for resawing, so I'm excited.

[Ryan Mooney]

Thanks for posting that up! I've been using pull elbows, which apparently negate this, but all things considered I've still be attempting to minimize how many corners I have

Yeah minimal corners is always good :)

If you haven't found it yet the wire lubricant also makes pulling MUCH MUCH easier (and safer as you're less likely to stretch/break the sheathing).

http://www.homedepot.com/p/Klein-Tools-32-oz-Premium-Synthetic-Clear-Lubricant-51028/100660159

https://www.amazon.com/s/?ie=UTF8&keywords=wire+pull+lubricant

[Brian Holcombe]

Awesome! I will buy that for the next round.

Since we're on the topic of my problems, I will bring this up and hopefully one of you guys has experience this before and can offer a rememdy.

My electric box is set into the drywall, I'm running conduit on the outside of the drywall (interior of the room). What's the best method to break through and then enter the box? Should I run conduit behind the wall to the back of a junction box? Another method? I've also considered running flexible conduit behind the wall. Open to suggestions.

[Malcolm McLeod]

Awesome! I will buy that for the next round.

Since we're on the topic of my problems, I will bring this up and hopefully one of you guys has experience this before and can offer a rememdy.

My electric box is set into the drywall, I'm running conduit on the outside of the drywall (interior of the room). What's the best method to break through and then enter the box? Should I run conduit behind the wall to the back of a junction box? Another method? I've also considered running flexible conduit behind the wall. Open to suggestions.

I would be tempted to mount a 4x4 box on the surface of the drywall and use this as the origin point for the conduit runs. Punch a hole thru the back of the box into the drywall cavity that's common to your junction box (careful not to damage any existing wires). You can then fish your wires from the new box into the junction box and land them on appropriate beakers and ground lugs. You may also need to remove a knockout plug from the junction box on the side that faces your new 4x4 box. No need for conduit once inside the wall.

Another possible solution, instead of the 4x4 box, might be a pair of 'LB' fittings (one on each conduit run) that turn 90* into the wall, but serve as a relatively neat penetration into the wall cavity...?

Edit: I'd advise killing the main beaker when you get ready to stick anything metal into the junction box. Saves suddenly working in the dark!

[Brian Holcombe]

Thanks for the ideas!

I will certainly kill the breaker when working in the box. I'm brave....but not that brave.

[Ken Schroeder]

Brian,
i think you would be well advised to hire a licensed electrician for this. (sorry). If you are having difficulty pulling the wires thorough the conduit, you have probably exceeded the code percentage of fill in the conduit. This is a safety no-no.

I am surprised that you would need number ten wire for a 240 volt circuit. That's a thirty amp draw. Normally that would be for appliances with a heating element or a hefty compressor. A residential saw motor or D.C. unit doesn't strike me as needing that much juice. I suggest you check the electrical requirements for your units.

From what you have written, I suspect this project us more involved than you realize. I believe your cost in hiring a professional would be money well spent.

Ken

ps Your questions are wise. Preceding without answers and skill would not be so wise.

[Brian Holcombe]

Thanks for your corncern, however I'm following the manufacturer's recommendations for wire and I'm going by Code on the wire fill for conduit.

Im not surprised by the suggested 10ga wire, the motor is 5hp.

[John K Jordan]

I am surprised that you would need number ten wire for a 240 volt circuit. That's a thirty amp draw. Normally that would be for appliances with a heating element or a hefty compressor. A residential saw motor or D.C. unit doesn't strike me as needing that much juice. I suggest you check the electrical requirements for your units.


There are several reasons I ran #10 for the 240v tool circuits when I built my shop. One, If I decide some day to upgrade to a stationary tool it is a lot easier to replace the breaker and receptacle than the wiring in the walls. Two, one of my runs is long and I didn't want to deal with the voltage drop. The cost of oversized wire is insignificant compared to the cost of building the shop.

JKJ

[Ken Schroeder]

Based on the information in your latest posts, I agree. It is wise to anticipate growth. The largest motor in my small home shop is 1/2 horse. I am pleased to learn that you have consulted the code. My concern was your fire safety.

Ken

[Charles P. Wright]

My MM16 came with no cord or plug (in March of this year); so I would have the plug/cord in hand so you don't have to wait to get it after getting the saw.

[Brian Holcombe]

Thanks Charles

[Arthur Fleming]

Code can be different from state to state, but I believe the NEC requires a disconnecting means if the breaker is more than 25 feet away,and also not in sight. The receptacle, and cord with cord cap, will serve as a disconnecting means. One advantage to running one conduit for the two circuits is you only have to run one ground wire. You would most likely have to go up a size in pipe, but it would probably still be less expensive than the two smaller conduits. I would love to see a picture of your prize, in the shop, all set up.

[Tim Bueler]

Since we're on the topic of my problems, I will bring this up and hopefully one of you guys has experience this before and can offer a rememdy.

My electric box is set into the drywall, I'm running conduit on the outside of the drywall (interior of the room). What's the best method to break through and then enter the box? Should I run conduit behind the wall to the back of a junction box? Another method? I've also considered running flexible conduit behind the wall. Open to suggestions.

Brian, in my new shop I picked up a couple of 1-1/2", electrical PVC 1/8 bends at the hardware store, glued them into a dog leg that comes out of the top of the panel to a surface mounted, 8" pull/junction box. From there I ran down the central wall in the shop with 1-1/2" EMT (high, almost against the ceiling) terminating in 6" pull/junction boxes as I went. About every 10'. Mounted to uni-strut so I didn't have to bend anything. This is my third (and last) shop and one thing I've learned is that I will move/remove/add/change things at some point in time. I can branch to 1/2" or 3/4" EMT from the 6" boxes and always, fairly easily pull a new circuit from the panel. Yep, it's visible, it's way oversize, and it cost me a couple hundred $ extra, but I'll never have to worry about it again. Don't forget to run a ground wire. I asked the electrical inspector if using EMT as ground was still acceptable and he said "Yes, but we'd like to see a separate ground wire." Point taken. Moot point with the PVC
fittings.

Now I have a stupid question for you. What is a MM20 saw?

[Brian Holcombe]

Code can be different from state to state, but I believe the NEC requires a disconnecting means if the breaker is more than 25 feet away,and also not in sight. The receptacle, and cord with cord cap, will serve as a disconnecting means. One advantage to running one conduit for the two circuits is you only have to run one ground wire. You would most likely have to go up a size in pipe, but it would probably still be less expensive than the two smaller conduits. I would love to see a picture of your prize, in the shop, all set up.

I saw that, and it makes good sense to me. I have planned an L6-30 for the MM20 bandsaw, today I'll find out if that planning is still accurate. I'll post up some pics when the shop is photo worthy, I have some painting/storage building to do in addition to installing the DC and ductwork.



Brian, in my new shop I picked up a couple of 1-1/2", electrical PVC 1/8 bends at the hardware store, glued them into a dog leg that comes out of the top of the panel to a surface mounted, 8" pull/junction box. From there I ran down the central wall in the shop with 1-1/2" EMT (high, almost against the ceiling) terminating in 6" pull/junction boxes as I went. About every 10'. Mounted to uni-strut so I didn't have to bend anything. This is my third (and last) shop and one thing I've learned is that I will move/remove/add/change things at some point in time. I can branch to 1/2" or 3/4" EMT from the 6" boxes and always, fairly easily pull a new circuit from the panel. Yep, it's visible, it's way oversize, and it cost me a couple hundred $ extra, but I'll never have to worry about it again. Don't forget to run a ground wire. I asked the electrical inspector if using EMT as ground was still acceptable and he said "Yes, but we'd like to see a separate ground wire." Point taken. Moot point with the PVC
fittings.

Now I have a stupid question for you. What is a MM20 saw?

MM20 is a 20" resaw capable bandsaw from Minimax (SCM group). Thanks for your thoughts on this.

My shop has a very limited capacity, and so I ran individual conduit to each location. My logic is that even if I add two more machines which would max out my space, then I could easily add those to the opposing wall without adding much complication to the setup.

If I were building a shop with a bit more space, I think I would follow along with your recommendation as it would make a good deal of sense.

I tend to agree, I decided to run a ground wire in each group of wires, that way it ensures a solid ground.

In racing cars I always found that a ground wire was better (for ignition systems) then grounding to a framing member. I presume this is similar, a large (not quite as large) electric motor can't be hurt by a 10ga dedicated ground wire.

[Arthur Fleming]

My experience is a ground wire is always preferable than using the conduit for a ground. I Have seen too many occasions where the connector/threaded locknut/box connection did not produce a satisfactory ground.

[Brian Holcombe]

I spoke with Oneida, they wire for an L6-20. The saw arrived, it does not come with a cord or box, supply your own cord.

[Brian Holcombe]

I've got the place moving along. Lighting up, wiring in, bandsaw...in. I had spare 10ga so I ran 10ga to the lamp as well...lol

Built a storage rack out of the pallet wood for my many many luggage as (not sure why I own so many luggage)

Enjoy:

https://brianholcombewoodworkerblog.files.wordpress.com/2016/12/img_5379.jpg

[Brian Holcombe]

V-3000 on its way....in a week or so. Looking forward to it, as sweeping up the loads of dust I've been making when resawing is not great.

[Jim Becker]

I spoke with Oneida, they wire for an L6-20. The saw arrived, it does not come with a cord or box, supply your own cord.

This is consistent with my experience...none of my MiniMax equipment, nor my Stubby Lathe come "pre-wired" with a cord/plug. That's pretty much standard with industrial equipment, as far as I know. I personally standardized on twist locks in my shop and buy the rubber coated cord at Home Depot. While it cost me a little more, I put pigtails on the machines with a mated pair of twist locks and then made up a custom length cord to get to the wall. But for those few times that I've needed to move something around, there was no cord to deal with during the mobility action.

Congrats on the new saw and DC!

[Chris Merriam]

I pushed my MM16 against the wall like that at first, but the doors can't swing fully open to put on a wide blade. Have you tried swapping blades yet? I ended up positioning the saw elsewhere in open space.

[Brian Holcombe]

This is consistent with my experience...none of my MiniMax equipment, nor my Stubby Lathe come "pre-wired" with a cord/plug. That's pretty much standard with industrial equipment, as far as I know. I personally standardized on twist locks in my shop and buy the rubber coated cord at Home Depot. While it cost me a little more, I put pigtails on the machines with a mated pair of twist locks and then made up a custom length cord to get to the wall. But for those few times that I've needed to move something around, there was no cord to deal with during the mobility action.

Congrats on the new saw and DC!

Thanks Jim! It was a lot of running around to get everything situated, but now that it's all set I'm happy and using the saw on the regular for resawing. Can't wait for the DC to arrive, I've coated the garage in sawdust a few times now, lol. Western red cedar lingers.


I pushed my MM16 against the wall like that at first, but the doors can't swing fully open to put on a wide blade. Have you tried swapping blades yet? I ended up positioning the saw elsewhere in open space.

I've noticed that, and basically just pull it out to open the doors all the way. I'm not sure I'll be swapping blades very often. I'd love to put it in open space but my 'auxiliary shop', is a single car garage that people walk through, or roll their bikes through and so forth.

[Jim Becker]

Yea, I had to adjust my MM16 out away from the wall slightly more than originally to make it a little easier during blade changing...not that I change the blade very often. Farther than I have it would be better, but I have just enough "open" to be able to get the job done.

[Ole Anderson]

Edit: I'd advise killing the main beaker when you get ready to stick anything metal into the junction box. Saves suddenly working in the dark!

Those LED headlamps are great for working on breaker panels in the dark basement. And rewiring your receiver, and installing your furnace, and unloading the wood crib after dark, and putting doors on your jeep after dark...don't know how I ever got along without it.