welding cable

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dshelley

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where I work the electrical contractor is running a 1/0 welding cable for a
310 amp motor his claim is that in the welding cable guide it is good for this amperage. My claim is that the NEC still applies 310-16 and 240
and the proper wire size should be 350 kcmil which is correct?
 
Welcome to the Forum!​

Sorry but you will have to increase the conductor size by 25% to feed a motor. The welding cable is not an approved cable unless it has a dual rating and then you are required to use the NEC defined cable. This is going to take more than 350 kcmil, At 387.5 amperes, it will take a circuit of 600 kcmil to feed the motor. :smile:
 
dshelley said:
where I work the electrical contractor is running a 1/0 welding cable for a
310 amp motor his claim is that in the welding cable guide it is good for this amperage. My claim is that the NEC still applies 310-16 and 240
and the proper wire size should be 350 kcmil which is correct?
Click to expand...

be afraid! be very afraid! :D AND listen to Charlie

I'm not sure where you get your "310" number, but motor currents should be selected as shown in 430.6. In any event, as Charlie states, that current x 1.25 gives you the ampacity for the required conductor.
The "welding cable guide" is basically useless for this application.
 
welding cable

we've already added the 125 percent

thanks for youre help.

ps does the NEC still applies in all cases. In other words the dual rating or special cables still apply to 310-16.
 
if you have done your 1.25 then 350 kcmil would be correct in most cases.
310 tables are applicable for the wires listed in each table, under each condition.
For NEC applications, you need to use a properly listed wire which you would normally find in 310.13.
95% of the time, you will be using a wire found in 310.13 with an ampacity listed in 310.16.
 
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welding

welding

I have'nt done all the calculations that was a (310 Amp) guess by my boss.
All I need to know is if you can or cannot use a size 1-0 awg welding cable to feed a a circuit in that range as defined by the contractor (310 amps).

Thanks D
 
augie47 said:
be afraid! be very afraid! :D AND listen to Charlie

I'm not sure where you get your "310" number, but motor currents should be selected as shown in 430.6. In any event, as Charlie states, that current x 1.25 gives you the ampacity for the required conductor.
The "welding cable guide" is basically useless for this application.
Click to expand...

...then there is the AHJ and engineering calculations/supervision thingie that can thread around those pesky NEC hinderances.:D

Or you can just go ahead - if you think it SHOULD be ok - and put your own posterior in the sling.....:wink:
 
dshelley said:
his claim is that in the welding cable guide it is good for this amperage.
Click to expand...

Welding cable used on a welder is sized based on the duty-cycle of the welder, which can range from 10% to 100%, I think.

It seems the contractor is using the welding cable guide because he is using welding cable. He should only use that guide when he is running welding cable to a welder - that's exactly what the guide is for, and most likely for nothing else.

If he doesn't understand this, time to get a new contractor.


Kent
 
Be careful with the diesel locomotive or welding cable. Cable marked only DLO in not code-complient.
Art 630, Electric welders does refer Conductor and to Welder cable but it's sort of sketchy.


The big issue is terminating the fine standed cable. Common lugs as supplied with breakers and control are UL486 which only can be used with cable that has either B or C stranding which is not made very clear by the manufacturers who supple their products with UL486 terminals.
 
dshelley said:
I have'nt done all the calculations that was a (310 Amp) guess by my boss.
All I need to know is if you can or cannot use a size 1-0 awg welding cable to feed a a circuit in that range as defined by the contractor (310 amps).

Thanks D
Click to expand...

You can get dual rated welding cable that is great for areas that you need flexibility. However you have to size it based on NEC ratings. And of course there is the issue of lugs rated for fine stranded if applicable.
 
don_resqcapt19 said:
But note that the ampacity given for the cable is at 90?C and in free air. Not too many NEC applications where you can use that ampacity. I think the same is true with the manufacturer's listed ampacity for welding cable.
Click to expand...

The manufacturer's table is immaterial. The question pertained to under what NEC identification can this material be used. Whichever NEC ampere table lists the identified conductor, it can be installed according to that and otehr pertinent sections of the NEC. We have also talked about that interpolation between non-listed sizes is likely to be accepted by the AHJ. If not the next smaller size current rating should not be an issue unless the AHJ really wants to be an appendix:grin:. If he is more lenient - and have some good judgement - he would accept the factory table as an engineering calculation. (BTW the lugs that you MUST use with this cable are rated for 90C.)
 
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