Welding Cable & Conductors in Cable Tray

[Sparky2791]

This is a two part question I am seeking input on;

Part I

I am looking for some input regarding 2008 NEC Article 630.41 & 630.42. The intension is to install a new 277/480V 400A panel to feed 8 welder receptacles using cable tray to install the MC Cable branch circuits for the receptacles. Plans were submitted and reviewed by a third party plan reviewer which is a requirement in order to receive an electrical permit. I did not prepare the drawings which were submitted however our client has come to us regarding the comments the reviewer made on the drawings one of which is requiring they be signed and sealed by a PE. The very first item he cited was;

Cable tray shall provide support at intervals not greater than 6? 630.42(a) A permanent sign shall be attached to cable tray every 20?. Sign shall read ?Cable tray for welding cables only? 630.42 (c)

I am questioning what the NEC is referring to where it says Welding Cable, Article 630 Part IV. We all know what the industry refers to as welding cable. However as far as the NEC is concerned there is no definition (at least none that I could find) for welding cable so, does this mean any type of cable (conductor) feeding a welder? Although in this case I am not feeding a welder I am feeding a receptacle which is used to plug a welder into. Seems odd why these conductors would be treated any differently than any other branch circuit conductor.:?

Part II

NEC Article 392 says if using single conductors in cable tray the minimum size it must be is 1/0 unless it is an EGC than minimum size is #4. What if I use a multi-conductor cable? There is no minimum size listed for this only that they are permitted to be installed in the cable tray 392.6 E. Is there a minimum cable size requirement?

 

[GoldDigger]

Part II: No. No size requirement.
But the cable must be listed as a wire type allowed in cable tray.

 

[RB1]

Liberty,

The MC cables feeding the welding receptacles are not welding cables and the reference to Part IV of Article 630 is incorrect. These are just branch circuit conductors installed in a cable tray system in a wiring method permitted by 392.3(A). The appropriate way to respond to the comment is "Duly noted".

 

[RB1]

To answer your question in more detail: Welding cables are covered under Product Category ZMAY in the UL White Book. These cables are intended to be used on the secondary circuits of electric welders.

 

[don_resqcapt19]

The title of Part IV in Article 630 needs work. It probably should read: "IV. Secondary Conductors (welding cable)"

 

[Sparky2791]

Liberty,

The MC cables feeding the welding receptacles are not welding cables and the reference to Part IV of Article 630 is incorrect. These are just branch circuit conductors installed in a cable tray system in a wiring method permitted by 392.3(A). The appropriate way to respond to the comment is "Duly noted".

Thanks. I agree, I would love to respond to the plan reviewers comment as 'Duly noted' however this will not suffice as a response and would lead to further discussions with them. I plan on responding explaining our position of the conductors being branch circuit conductors. Thanks for yours and Dons comments.

 

[Sparky2791]

The title of Part IV in Article 630 needs work. It probably should read: "IV. Secondary Conductors (welding cable)"

If they were to give a definition of what they consider welding cable it would clear a lot of things up. I do question why anyone would install welding cable in a cable tray though.:?
I guess there are applications where it would benefit.

 

[GoldDigger]

If they were to give a definition of what they consider welding cable it would clear a lot of things up. I do question why anyone would install welding cable in a cable tray though.:?
I guess there are applications where it would benefit.

Mostly we hear of welding cable being used for system voltage where extreme flexibility is wanted, beyond what portable cord or other fixed wire types could provide. Same reasons some want to use DLO (locomotive) cable. But the code does not permit that in general unless the wire is dual listed as another Chapter 3 type.

 

[templdl]

Mostly we hear of welding cable being used for system voltage where extreme flexibility is wanted, beyond what portable cord or other fixed wire types could provide. Same reasons some want to use DLO (locomotive) cable. But the code does not permit that in general unless the wire is dual listed as another Chapter 3 type.

If it is allowed to to used attention must be made toward the termination methods as the common termination as supplied on devices are UL486 listed which doesn't include this conductor.

 

[iceworm]

... install a new 277/480V 400A panel to feed 8 welder receptacles using cable tray to install the MC Cable branch circuits for the receptacles. ...

Questions (probably do not apply):
How did you set the overcurrent protection?

Are you using the rules of 630 to set the OCP above the ampacity of the conductors?

Reason I ask is 99.99% of all the "welding receptacles" I've seen are really 480V convenience receptacles scattered about an industrial plant. They are always protected at the conductor ampacity. Is this what you are doing, or are you actually installing dedicated welding machine receptacles?

ice

 

[RB1]

Liberty,

I would respond "duly noted" because the comment doesn't ask for a plan correction and it is irrelevant to the installation.

 

[GoldDigger]

Liberty,

I would respond "duly noted" because the comment doesn't ask for a plan correction and it is irrelevant to the installation.

I, on the other hand, would interpret "duly noted" as a promise to install the requested warning signs, and would rather iron it out now than slide through the plan check and have it come up on final!

 

[GoldDigger]

I, on the other hand, would interpret "duly noted" as a promise to install the requested warning signs, and would rather iron it out now than slide through the plan check and have it come up on final!

To me it appears that the plan checker's intention was to have his language added, almost verbatim, into the plan. Of course it is hard to judge his intent accurately from this end of the internet.