Comment, Electrical Question and a Gloat

Well early Sat. Morning I went to U-Haul and picked up a 4x8 trailer and headed to General Industrial Supply in Nashville. Rick (great guy, the owner) loaded me up with a nice Powermatic 66. I had saved up for a left tilt Jet, but they weren't getting any "Scratch and Dent". As time has marched on, the war chest had grown and I really needed to finish a crown molding job for SWMBO. She asked me one day

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"when are you going to get that table saw you keep talking about so you can put up my crown molding?"

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I just hated to tell her that I could do it w/o the saw, but I did want to rip some bevel backers from 2x4 and I had sworn off ripping long stock on my RAS years ago. Blah Blah Blah. An hour later I was back on the road to Knoxville. That was the gloat.

I managed to get the 500 pound saw out of the U-Haul and onto a piece of plywood by myself (the 3 helpers that said they would help me unload disappeared).And slowly into my shop. Whew. I have now installed the 54" fence and am going to have make some changes in my layout.

Question: I wired my outlets with the 4 wire cable in 10 guage; 2 hots, a common and a ground from a 30 AMP breaker in the sub panel. I have an isolated ground bar in the sub that is tied to the main panel by the lead wire and the common is also connected to the main panel by the lead wire. In the main panel the commons and grounds are tied together. I'm using the 4 terminal outlets (30 amp twist locks) and have the 4 wire 30 amp twist lock plug to match. Now the saw motor diagram and switch have instructions for the 2 hots and ground, so I'm thinking of getting 15 feet of 10 guage 2 wire and a ground and leaving the common empty when connecting to the plug. Or should I get 3 wire with a ground and connect both the common and ground in the switch?

Thanks for your help!

Hal

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Originally Posted by Hal Flynt

Question: I wired my outlets with the 4 wire cable in 10 guage; 2 hots, a common and a ground from a 30 AMP breaker in the sub panel. I have an isolated ground bar in the sub that is tied to the main panel by the lead wire and the common is also connected to the main panel by the lead wire. In the main panel the commons and grounds are tied together. I'm using the 4 terminal outlets (30 amp twist locks) and have the 4 wire 30 amp twist lock plug to match. Now the saw motor diagram and switch have instructions for the 2 hots and ground, so I'm thinking of getting 15 feet of 10 guage 2 wire and a ground and leaving the common empty when connecting to the plug. Or should I get 3 wire with a ground and connect both the common and ground in the switch?

Thanks for your help!

Hal

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Hal, you disgust me, I am jealous of your new saw. :)

What you need is the two hots and an equipment ground. NEVER connect the common and ground together at any place except at the main panel where the electric meter is attached. Unless you have a need for 120v. in the saw, you don't need the white common. I'd go with the 10-2 plus ground.

All based upon never having seen the machine.....

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Originally Posted by Hal Flynt

Question: I wired my outlets with the 4 wire cable in 10 guage; 2 hots, a common and a ground from a 30 AMP breaker in the sub panel. I have an isolated ground bar in the sub that is tied to the main panel by the lead wire and the common is also connected to the main panel by the lead wire. In the main panel the commons and grounds are tied together. I'm using the 4 terminal outlets (30 amp twist locks) and have the 4 wire 30 amp twist lock plug to match. Now the saw motor diagram and switch have instructions for the 2 hots and ground, so I'm thinking of getting 15 feet of 10 guage 2 wire and a ground and leaving the common empty when connecting to the plug. Or should I get 3 wire with a ground and connect both the common and ground in the switch?

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The white wire is not a "common"...it's a "neutral" and only used for 120v circuits. 240v Power tools don't need that lead and most folks use 2 conductor plus ground for the entire circuit and a three prong twist lock rated to match the circuit. (Less expensive, too) Four wire is only used for dryers and other appliances that need both 120v and 240v supply.

But since you already have the four conductors recepticals and plugs, leave the neutral unwired on the saw cable's male plug. The two hot conductors on the motor lead should match up with the two hot conductors in the receptical and the grounds should also correspond. Be sure that you can easily access the plug for disconnection for blade changes, etc. Some folks actually use a short pigtail at the saw with a male plug and an extension "exactly" to length from there to the outlet (Properly rated, of course) for easy access to a plug at the saw.

Your subpanel sounds like it is wired properly as the ground and neutral are isolated per code.

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Originally Posted by Jim Becker

The white wire is not a "common"...it's a "neutral" and only used for 120v circuits. Power tools don't need that lead and most folks use 2 conductor plus ground for the entire circuit and a three prong twist lock rated to match the circuit. (Less expensive, too) Four wire is only used for dryers and other appliances that need both 120v and 240v supply.

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Yes, I agree that the correct term is neutral. In reality, it is the center tap on the 240v secondary of the pole pig. Terms, terms, terms, I can't even get my "fix'n tos" down right. :confused:

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Originally Posted by Hal Flynt

I have an isolated ground bar in the sub that is tied to the main panel by the lead wire and the common is also connected to the main panel by the lead wire. In the main panel the commons and grounds are tied together. I'm using the 4 terminal outlets (30 amp twist locks) and have the 4 wire 30 amp twist lock plug to match. Now the saw motor diagram and switch have instructions for the 2 hots and ground, so I'm thinking of getting 15 feet of 10 guage 2 wire and a ground and leaving the common empty when connecting to the plug

Hal

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Hal,

Jim and Ken already sort of hit on this, but it's an NEC requirement that your subpanel's neutral and grounding (technically the "grounded" and "grounding", respectively) busses are not bonded or tied together in the subpanel. You indicate that you have an "isolated ground bar". That isolated bar is where your neutral should connect. From a color perspective, that would be the white conductors. The ground is directly mounted to the subpanel and is where the green/bare conductors go. Make sure that, unless the bars are specifically rated for "multiples", that you only terminate 1 conductor per hole in the bars.

If your ground is isolated ("floating") and the neutral is tied to the case of your subpanel - things are wired backwards and create a hazardous situation.

You've already got it on the basic wiring for the saw. The only other thing to consider is, if you're ever going to build a router table into the saw extension table - run 10/3+ground to the saw. Attach (2) boxes to the saw - (1) with a 240 receptacle for the saw and (1) with 110 outlets for your router. If you don't ever expect to do the router table thing, the 10/2 is just fine.

Rob (Addy protocol : unlicensed homeowner electrician)

I am sure glad I read this thread. I have run (not connected on etiher end) a 10-4 wire from my main breaker panel to a junction box that will eventually be connected to an oven. It never occured to me that the oven would also need 110. Here's the configuration. In the breaker panel the Red and Black are [will be] connected to the breaker [double pole] and the green and white [will be] connected to the same terminal block. Correct? I presume the oven will have wiring instructions for the oven end. I am not sure of the term "isolated" or "floating". The ground bar driven into the ground with a bare copper wire is tied to the physical breaker box. The neutral terminal strips are screwed to the box making the neutral "ground". None of my current 220 circuits use four wire. I have a dyer and two HVAC units - and my Unisaw.

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Originally Posted by Byron Trantham

In the breaker panel the Red and Black are [will be] connected to the breaker [double pole] and the green and white [will be] connected to the same terminal block. Correct?

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Yes, on the Red and Black "hot" wires, but no on the neutral and ground. Your white wire goes to the neutral buss, and the bare ground goes to the ground buss. Although these two busses are actually bonded in your main panel, you must still observe proper locations for each of these connections in the box. If "previous" installers mixed the grounds and neutrals, they did not do things to code.

That's thank you in Japanese. You guys are most helpful!!!

Pardon my nomenclature in my original post and here too. I believe I have done it correctly.

The "ground" in my sub panel is "grounded to the sub panel" and connected to the main through the bare #2 wire to the Main panel neutral/ grounded/ common buss, which is attached to the in ground copper rod by a bare copper wire.

The "neutral" is isolated from the sub panel, and likewise fed by the White common insulated #2 wire from the main where it attaches to the neutral buss.

The 2 hot insulated #2 wires are powered by a 90AMP circuit breaker in my main panel to the 2 power busses in my sub panel.

I have a dedicated router table with the Jointech fence that just happens to be the same height as my saw table and it will double as an out feed now.

I have placed one of my 240v outlets on the wall just above table height at the end of the side table, and one overhead on the other side of my shop (one circuit/2 outlets/so amp feed). I placed 20amp duplex and quadplex (?) outlets every 3.5 feet along one wall with a 120v duplex adjacent to the 240v. I also have a single 20 amp quad outlet where my Dust collector and compressor reside.

Now I will get some 10/2 w ground and hook her up. I like the idea of the pig tail or a disconnect near the switch and will contemplate that a bit.

Thanks a lot, I have a need for saw dust.

Hal

That's weird. An electrical contractor wired our house [13 years ago] and it was inspected by the county.

On each bank of breakers there is a buss bar. Both white and bare copper (ground on a 110 circuit) are attached to the same bar. If the buss bars are at the same electrical point, what difference does it make with regard to physically separating the bare copper and the white neutral into two separate buss bars? I presume floating comes in here somewhere but not in a typical house wiring scheme. Floating to me would mean isolated from the box in some way. For what reason, I can't imagine.

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Originally Posted by Byron Trantham

That's weird. An electrical contractor wired our house [13 years ago] and it was inspected by the county.

On each bank of breakers there is a buss bar. Both white and bare copper (ground on a 110 circuit) are attached to the same bar. If the buss bars are at the same electrical point, what difference does it make with regard to physically separating the bare copper and the white neutral into two separate buss bars? I presume floating comes in here somewhere but not in a typical house wiring scheme. Floating to me would mean isolated from the box in some way. For what reason, I can't imagine.

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Well...it's not uncommon for it to be that way, but the inspectors in my area would not allow it. When I had my main panel replaced last November, I noticed how careful the electrician was about this and he indicated that it was one of those little things that "some" inspectors will nail you for if they are feeling ugly. Theoretically, keeping the neutral and ground on separate buss bars allows for the potential of un-bonding them should it be necessary for some reason, like trouble shooting or if that panel for some reason gets turned into a subpanel off of a larger main later on. At any rate...I wouldn't change what you have.

The "ground" in my sub panel is "grounded to the sub panel" and connected to the main through the bare #2 wire to the Main panel neutral/ grounded/ common buss, which is attached to the in ground copper rod by a bare copper wire.



Hal,
This would not be acceptable in my area. Unless the sub panel is located in the same building as the main panel. If the sub panel is located in another building, then the ground bus must be connected to it's own grounding rod.

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Originally Posted by John Christiansen

The "ground" in my sub panel is "grounded to the sub panel" and connected to the main through the bare #2 wire to the Main panel neutral/ grounded/ common buss, which is attached to the in ground copper rod by a bare copper wire.



Hal,
This would not be acceptable in my area. Unless the sub panel is located in the same building as the main panel. If the sub panel is located in another building, then the ground bus must be connected to it's own grounding rod.

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It is the same building. Just the other side in the basement.

Thanks.

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Originally Posted by John Christiansen

This would not be acceptable in my area. Unless the sub panel is located in the same building as the main panel. If the sub panel is located in another building, then the ground bus must be connected to it's own grounding rod.

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From NEC (1999) Article 250-32,

"Exception: A grounding electrode at separate buildings or structures shall not be required where only one branch circuit includes an equipment grounding conductor for grounding the non-current carrying parts of all equipment."

For example, a single circuit run out to a shed does not require a ground rod. According to the AHJ for my town (spoke with him this morning), I will not need a separate ground rod for a branch circuit feeding a subpanel I'm installing in our shed.

Rob

Rob, would the use of a "double-grounded" (two prong) handheld power tool invalidate that article?

Dave

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Originally Posted by Dave Arbuckle

Rob, would the use of a "double-grounded" (two prong) handheld power tool invalidate that article?

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This applies to the supply side specifications. Double-insulated tools are a whole different matter...and I believe governed by a different organization, if I am not mistaken. (UL in the US/ CSA in Canada)

Exception: A grounding electrode at separate buildings or structures shall not be required where only one branch circuit includes an equipment grounding conductor for grounding the non-current carrying parts of all equipment.

Cause of question, the non-current carrying parts of that equipment is not grounded.

The Underwriter's Laboratory does have standards regarding power tools, stationary and portable. Compliance to their standards is not mandatory though, there are some pretty prominent tool makers that do not UL list their equipment.

Dave

Dave,

I don't see the grounding or insulative properties of a "cord and plug" connected appliance as affecting the "grounding conductor" requirement for the circuit. What difference does it make to the appliance (tool) if the grounding conductor is grounded to a local ground rod or connected via a conductor to the service's main GES (Grounding Electrode System) back at the service panel? Either way it's got an equipment ground. If the tool is only 2-prong, again how does it affect the premises wiring?

Rob
(Addy protocol : unlicensed homeowner electrician)

Dunno, Rob. That's why I asked, the NEC Article looked like it was specific. I probably don't understand the phrasing they are using.

Dave

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Originally Posted by Hal Flynt

Well early Sat. Morning I went to U-Haul and picked up a 4x8 trailer and headed to General Industrial Supply in Nashville. Rick (great guy, the owner) loaded me up with a nice Powermatic 66. I had saved up for a left tilt Jet, but they weren't getting any "Scratch and Dent". As time has marched on, the war chest had grown and I really needed to finish a crown molding job for SWMBO. She asked me one day I just hated to tell her that I could do it w/o the saw, but I did want to rip some bevel backers from 2x4 and I had sworn off ripping long stock on my RAS years ago. Blah Blah Blah. An hour later I was back on the road to Knoxville. That was the gloat.

I managed to get the 500 pound saw out of the U-Haul and onto a piece of plywood by myself (the 3 helpers that said they would help me unload disappeared).And slowly into my shop. Whew. I have now installed the 54" fence and am going to have make some changes in my layout.

Question: I wired my outlets with the 4 wire cable in 10 guage; 2 hots, a common and a ground from a 30 AMP breaker in the sub panel. I have an isolated ground bar in the sub that is tied to the main panel by the lead wire and the common is also connected to the main panel by the lead wire. In the main panel the commons and grounds are tied together. I'm using the 4 terminal outlets (30 amp twist locks) and have the 4 wire 30 amp twist lock plug to match. Now the saw motor diagram and switch have instructions for the 2 hots and ground, so I'm thinking of getting 15 feet of 10 guage 2 wire and a ground and leaving the common empty when connecting to the plug. Or should I get 3 wire with a ground and connect both the common and ground in the switch?

Thanks for your help!

Hal

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Hal, next time you need help, give me a call--I'm in knoxville

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Originally Posted by Gary Hoemann

Hal, next time you need help, give me a call--I'm in knoxville

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Thanks for the offer, I just may do that. When you are travelling west on I-40 at the Gallaher View Exit, give a wave. I'm in the corner office of the Mortgage Investors building. I also give road reports.

Hal, what the previous posters are trying to tell you is...according to NEC
for your saw power outlet you need two hot wires and an equipment ground wire ( no neutral). In electrical terminology your panel that feeds the saw is a sub panel from the main panel, a sub panel must have an
isolated neutral busbar, one that is not electrically bonded to the panel itself. No other wires should be connected to this busbar except neutral
wires (white in color or gray striped conductor).

What a lot of people fail to understand about electrical terminology is the difference between "grounded conductor" (neutral or return path for current) and "grounding conductor" the bare copper wire or green coated
wire. It is merely a safety conductor for shock prevention to equipment
user, in case of malfunction of circuit conductor(s). Hope this helps...

Jim.....This thread has not had an entry for over 5 years. I suspect Hal has long ago solved the problem!

Align those miter slots to the blade, and then the fence to the miter slots, and you'll be good for years.

The PM66 is the 1955 Chevy Belair of cabinet saws. Good score. Enjoy.

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Originally Posted by Hal Flynt

Rick (great guy, the owner) loaded me up with a nice Powermatic 66.

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EDIT - Arrrgh.... I did not notice the age of this thread. So sorry.