Parallel Conductors in Flexible Cords/Cables

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dbuschor

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Does the code allow parallel conductors to be ran via flexible cords?

For instance, I have a 460V, 208A 1 phase induction heater for a piece of process equipment (that is interchanged on a weekly basis). [meets 400.7(6), portable cord/cable uses]

Can I run a 1/0, four wire, Type G flexible cord from the control panel to the heater via a 200A four pin plug & receptacle? Use two in parallel for the hot and two in parallel for the neutral? [meets 310.4, parallel conductor requirement ? same type, same length, same termination, etc.]
 

petersonra

Senior Member
Location
Northern illinois
Occupation
engineer
Re: Parallel Conductors in Flexible Cords/Cables

I think so but I also think you have to derate it to 80%.

I think you also have to run an egc in this cable.

[ November 16, 2005, 12:14 PM: Message edited by: petersonra ]
 

dbuschor

Member
Re: Parallel Conductors in Flexible Cords/Cables

So you don't have any concerns with the plug/receptacle not meeting section 310.4?

Okay, then lets take it to the next step...

The heater control panel has three of these heaters and I have an option to mount the panel on the base of the equipment, but then I'll need a portable cord (plug/receptacle) to supply the panel.

Can I run a 3 phase 3 wire, 480V, 600A supply using three portable cables, each being a 1/0 3C W/G (3 parallel conductors per phase), with each phase on individual plugs/receptacles?

I could essentially supply 600A service - 200 amps per 1/0 conductor (x 3 per leg). Note that the plug/receptacle is rated for 200A.
 

pierre

Senior Member
Re: Parallel Conductors in Flexible Cords/Cables

You need to take a look at 250.122(F)(1).

It is usually difficult to find cables that will have an equipment ground conductor sized for the size of the overcurrent device that is protecting the parallel conductors.

250.122 for a 600 amp overcurrent device would require a 1 AWG conductor within the cable.
Don't forget about the lengths and proximity of the cables/conductors.


3 sets of 1/0 are not going to get you to 600 amps... more like 450 amps - see 240.4(B)(2) and then look at 240.6.

[ November 16, 2005, 01:48 PM: Message edited by: pierre ]
 

dbuschor

Member
Re: Parallel Conductors in Flexible Cords/Cables

You need to take a look at 250.122(F)(1).

It is usually difficult to find cables that will have an equipment ground conductor sized for the size of the overcurrent device that is protecting the parallel conductors.

250.122 for a 600 amp overcurrent device would require a 1 AWG conductor within the cable.
Don't forget about the lengths and proximity of the cables/conductors.
Could I use a 1/0 4/C cable and use the 4th conductor as a ground?


3 sets of 1/0 are not going to get you to 600 amps... more like 450 amps - see 240.4(B)(2) and then look at 240.6.
If these cables are drooped over supports (in free air) and don't have more than 3 current carrying conductors, doesn't table 400.5(B)(90C-F3) apply (given the cable is rated for 90C)
 

dbuschor

Member
Re: Parallel Conductors in Flexible Cords/Cables

Originally posted by petersonra:
where did you come up with 600A?

the OP says it is a single phase 460V/208A heater.
I used 600 as a theoretical max based on the 200A plug/receptacle. The OEM only requires 310 kVA (there are two 208A heaters and one 60A heater on the equipment which are powered by this one panel).

[ November 16, 2005, 02:56 PM: Message edited by: dbuschor ]
 

petersonra

Senior Member
Location
Northern illinois
Occupation
engineer
Re: Parallel Conductors in Flexible Cords/Cables

I don't see any reason you cannot use a single cord to supply a single heater at 208A IF you used a 5 wire cable. 2 each for one phase, 2 for the other phase, and one ground.

Even derated to 80% it should be adeqaute.
 

dbuschor

Member
Re: Parallel Conductors in Flexible Cords/Cables

Originally posted by petersonra:
I don't see any reason you cannot use a single cord to supply a single heater at 208A IF you used a 5 wire cable. 2 each for one phase, 2 for the other phase, and one ground.

Even derated to 80% it should be adeqaute.
Is there a way to apply this concept (parallel conductors via flexible cords with attachment plugs) to the 480V, 3 phase, 310 kVA supply going to the control panel?
 

mhulbert

Senior Member
Location
Chico, CA
Re: Parallel Conductors in Flexible Cords/Cables

If you are connecitng these with multiple cord caps, won't the male prongs be hot when one cap is plugged in and the other isn't??? Maybe I am not visulaizing your setup correctly!?

Have you though about going with CamLock connectors? They are typically used for high power apps in the entertainement (and other) industries. They have them up to 690 Amps.

Check out this catalog (PDF).
 

dbuschor

Member
Re: Parallel Conductors in Flexible Cords/Cables

Originally posted by mhulbert:
If you are connecitng these with multiple cord caps, won't the male prongs be hot when one cap is plugged in and the other isn't??? Maybe I am not visulaizing your setup correctly!?

Have you though about going with CamLock connectors? They are typically used for high power apps in the entertainement (and other) industries. They have them up to 690 Amps.

Check out this catalog (PDF).
This might be an option, what cable/wire do they typically use?
 

petersonra

Senior Member
Location
Northern illinois
Occupation
engineer
Re: Parallel Conductors in Flexible Cords/Cables

I use these a lot. they work pretty good.

I have better luck actually getting the leviton version though. they are more readily available, cost less, and have smaller minimum order quantities then the camlok version in this size. and they are completely interchangable.
 

mhulbert

Senior Member
Location
Chico, CA
Re: Parallel Conductors in Flexible Cords/Cables

Typically, these are used with single conductor flexible cord...I believe it's labeled as SOW, and they can also be used with the super flexible dual-listed locomotive cable, though I believe you have to use the crimp version for this.

An example of the cord is here.They have up to 4/0, but I have seen bigger. Call an enetertainment lighting company in your area, as they use a ton of this stuff and can probably connect you with a local source.

Also, I forgot to mention- it is standard practice in the enetertainment/movie indusry to wire the neutral and ground in the opposite gender as the pahse conductors. So, if you have females on your drop to your equipment for the phases, you should have males on neut and ground. This prevents somebody from connectiong gorund or neutral to a phase conductor. Also, it goes without saying- you don't want to connect/disconnect these things under load.

mike
 
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