grounded vs non-grounding

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  #1  
Old 07-30-03, 09:36 PM
jeepers
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grounded vs non-grounding

I recently installed a 250 volt 30 amp dual pole circuit to my garage.
10/2 wire from breaker to dryer outlet.
Question is this.

I need to make an extension cord of sorts for this item. (Welder).
I thought I could take 10/2 wire put a dryer plug on one end and a dryer outlet on the other.(Flush type enclosed)

When I started to wire everything up to make the extension cord, I discovered that the dryer outlet is marked non-grounding and has a caution that "This device is not for grounding use." on the box.

What the heck is it talking about and can I use it to complete my extension cord for the welder?
 
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  #2  
Old 07-31-03, 04:51 AM
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Does the wire come from the main service entrance panel or a subfed panel? A welder and a dryer are set up a bit different. If it comes from the main it will work fine, the only non code compliant aspect would be the color of the wire. In fact your dryer wont be code anyway, that wire should have been 10/3 with ground. The welder will be as it uses 10/2 with ground. Ok,, I read thjis again for the 3rd time,, you are not using the same wire for a dryer circuit? Just the welder? What you are doing will work fine. You should really get a receptical that is made for the welder though.
 

Last edited by sberry27; 07-31-03 at 05:09 AM.
  #3  
Old 07-31-03, 09:08 AM
DaveB.inVa
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The dryer receptacle is marked non grounding because the L shaped terminal is actually for the neutral. It just so happens that in oven/dryer connections ONLY that the frames of the said appliances are allowed to be grounded by the neutral.

SBerry is correct, you should have used 10/3 when making a new dryer connection plus remove the bonding connection on the dryer which connects the ground and neutral.

Using 10/2 NM cable (Romex) is a code violation for a dryer anyway because the neutral is bare and not part of a SE cable assembly. {250.140 (3)}
I dont have a UL book with me but I am also pretty sure that using NM cable (Romex) as an extension cord isnt legal either.

A much better choice for this extension cord would be SO type cable... its meant to be used this way.
 
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Old 07-31-03, 10:13 AM
jeepers
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ADDITIONAL INFO.

I AM NOT USING THE OUTLET FOR A DRYER. IT IS STRICTLY FOR THE WELDER. WHICH ONLY HAS 3 WIRES. THE WELDER IS LOW VOLT HIGH AMP ARC TYPE. THE TWO HOT WIRES ARE LEFT AND RIGHT WITH A NEUTRAL (ON THE BAR) IN THE MIDDLE. THE EXTENSION CORD WILL ONLY BE USED EVERY ONCE IN A WHILE AND IS NOT MEANT TO BE A PERMANENT CONNECTION.

AS YOU KNOW IN THE CASE OF A WELDER YOU ARE MAKING A GROUND WITH YOUR GROUND CLAMP.

THE HOME DEPOT AND LOWE'S DID NOT HAVE EXACTLY WHAT I WANTED SO I DID WHAT I THOUGHT WOULD WORK AND BE SAFE.

I MAY USE THE WELDER 30 HOURS IN A YEAR AND WITH THE EXTENSION CORD 1/2 THE TIME.

SO WILL THIS WORK AND NOT ELETRICUTE ME WHEN I COMPLETE THE GROUND WITH THE GROUNDING CLAMP??
 
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Old 07-31-03, 10:33 AM
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If you look inside the dryer receptacle box what colour of wires do you see there?
At present it sounds like you dryer receptacle is connected to two
hots and a neutral and no ground wire The welder requires two hots and a ground. This is not impossible to get around just need to know exactly what we are dealing with.

The grounding clamp on the welder is not the same thing as and equipment ground in the welder. So it is important to maintain a good ground from the input.
 
  #6  
Old 07-31-03, 10:39 AM
DaveB.inVa
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Exclamation

Dude you dont have to yell plus my vision is fine so the caps are unneseccary.

First let me say I am not in the business of making things work, just so they work. I am in the business of making things work correctly and safely according to the National Electrical Code as well as other safety codes that may apply.

With your present configuration the welder will work.

Note however that the welder probably doesnt use a dryer receptacle. It probably uses a 240v grounding type receptacle. This should have 2 straight blades and a round pin for grounding. So the proper receptacle should be used ie probably not a dryer receptacle! Also when NM is used in the manner you describe with the white wire being a hot conductor you must reidentify the ends with a marker so noone will believe its a neutral.

On your welder the bare is not a neutral. The welder is most likely a straight 240v piece of equipment and doesnt require the neutral as it is only provided for 120v loads. The bare wire is an equipment ground. It is there incase of an internal fault. Should this fault occur the grounding conductor will provide a low impedance path for current allowing a breaker to trip.

The secondary "ground" has absolutely nothing to do with the primary ground. What you are using is simply an isolation transformer that may or may not have rectifiers to provide a DC setting so there is no real reason to be concerned with being electrocuted when putting on the ground clamp.

I still view the hack extension cord as trouble. No matter how long its used or for what duration it was not meant to be used that way. The solid conductors in the NM cable werent meant to be flexed for 15 hrs, NM cable isnt provided with means to protect the conductors when used as an extension cord. The sheath is too thin and not flexible enough.

SO cord is meant to be flexed using stranded conductors, its sheath is thick. You can walk on it roll junk over it and it will take the abuse... NM would fail!
 
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Old 07-31-03, 04:10 PM
jeepers
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yelling

Sorry about the all caps. Did not intend to cause anyone to feel that I was yelling.

Please make sure I understand this.

1- Change the dryer receptacle, but otherwise the wiring I ran in the wall is okay?

2- The cord will work if I change the type of wire and the means of connection?
 
  #8  
Old 07-31-03, 04:17 PM
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I had to re read it a couple times at first,, then I understood what you were after. No, it isnt inheriantly unsafe to do what you are doing,,, other than the steel back of a dryer recept isnt bonded with a rivit to the grounding pin. Thats why it is listed with the instructions the way it is. Thats the biggest obstical that would be a potential danger. You should remark the white wire with black tape on both ends. Probably every electrician at one time or another has done exactly what you are doing. Its just that sometimes doing it yourself and offering it up as advice is another matter. (like gard said,, you can get around it) But most of the time the answers you get here are going to be near to the letter of the code. Personally I think a piece of SO cord is a great investment and could give lots of years of service. Ok,, by the way I have a COUPLE of those dryer type cords, not romex but it made me think I should add a bonding jumper to the steel boxes they are in, they are for welding supplys also.
 
  #9  
Old 07-31-03, 08:03 PM
jeepers
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My heart felt thanks.

Since all of you guys have been nice enough to help me, here now is the rest of the story so that you may understand why I am doing this the way that I am.

I am moving in a few months. Before I move the circuit that I added will be changed to two circuits wired for 20 amps each.
(Yes I can do it to code.) Believe it or not I wired my own shop that I built and it passed inspection.)

The circuit was added to my garage because I am building a prototype of a piece of equipment. I need the welder to do this. The 30 hours of welding will be stretched out over a long period of time. Once the project is complete I will be getting rid of the welder and I will change the current circuit so that when I sell my house no one will have to worry about what I did to use the welder.

My experience and background are in the mechanical power transmission field not the electrical that is why I turned to the people on this board for help.
 
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