Conductor Size for 480 Vac @ 430 Amps ?

[dwirebender]

I am trying to size the conductors in my measurement enclosure.

I have 3 conductors passing through current transformers to measure the load of tested equipment.

The enclosure is a 36 x 60 x 12. Except for measuring equipment there is noting else in the box.

How do I size this conductor.

Max load is 480 VAC at 430 Amps. It will vary.

350mcm welding cable has been suggested.

Obviously I'm looking for the smallest possible conductor.

DLO is also an option.

Can I get an opinion from someone...?

 

[jumper]

How is 350 kcmil good for 430 amps?

 

[bob]

Is the conductor entering the enclosure in conduit? Continuous Load?
One circuit or more?


Size 60C 75C
1/0 125 150
2/0 145 175
3/0 165 200
4/0 195 230
250 215 255
300 240 285
350 260 310
400 280 335
500 320 380
600 355 420
700 385 460

 

[bob]

Check this article before you buy the welding cable

http://www.plsn.com/index.php?option=com_content&task=view&id=4896&Itemid=40

 

[iamintn]

Is voltage drop an issue? How long of a run?

262.6 MCM DLO is good for about 460A and is about 1" OD if memory serves.

 

[wireguy8169]

Bob,

excellent article....

 

[petersonra]

rather than run huge wires like that is there some place you can put the CTs where the wires already are? they don't take up much room.

 

[Jraef]

Another reason not to use DLO or Welding cable is that you MUST use approved connectors for it. Most off-the-shelf mechanical lugs and compression lugs are NOT rated for use on those fine strand cables. About the only thing legal to use on them are specifically rated compression lugs and a lot (most?) suppliers don't have them readily available, they have to order them.

Another good article on the subject, albeit for the PV industry, it applies to all uses of those cables.

 

[don_resqcapt19]

Is voltage drop an issue? How long of a run?

262.6 MCM DLO is good for about 460A and is about 1" OD if memory serves.

I assume that ampacity came from the cable manufacturer. If so it is based on 90?C and in free air. That ampacity cannot be used for NEC applications. Also, you can't even use the DLO for NEC applications unless it is dual listed as one of the cable types found in the NEC.

 

[lakee911]

Check this article before you buy the welding cable

http://www.plsn.com/index.php?option=com_content&task=view&id=4896&Itemid=40

Good article. I had always wondered why welding cable kept coming up. Also, I see lots of references to I think it is locomotive type cable or something. Use something designed for the intended purpose!

 

[jumper]

I assume that ampacity came from the cable manufacturer. If so it is based on 90?C and in free air. That ampacity cannot be used for NEC applications. Also, you can't even use the DLO for NEC applications unless it is dual listed as one of the cable types found in the NEC.

Okay, so even though I am an idiot, I am not crazy(maybe).

350 kcmil, or whatever is similar in DLO, is too small?

 

[don_resqcapt19]

Okay, so even though I am an idiot, I am not crazy(maybe).

350 kcmil, or whatever is similar in DLO, is too small?

Most of the dual listed DLO I have seen is listed as RHH, so I would use the 75?C ampacity of 350kcmil from Table 310.16.

 

[robh]

Check this article before you buy the welding cable

http://www.plsn.com/index.php?option=com_content&task=view&id=4896&Itemid=40

Thanks. Good article.