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ampacity?

ampacity?

ampacity?

(OP)
In a residence, can I use #6thhn, (copper) to feed from a 70a 2pole breaker in the main breaker panel to feed to a small subfed panel, or do I need to use #6thhn. Also, do I have to size the wire for the breaker being fed from, or for the rating of the sub-fed panel (125a)? Thanks!!


designered

RE: ampacity?

Is there a difference between #6thhn and #6thhn?

Gunnar Englund
www.gke.org
--------------------------------------
100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...

RE: ampacity?

(OP)
sorry, meant to say...."or do I need to use #4 thhn.

designered

RE: ampacity?

#6 is only good for 60A per NEC. (I assume you are in the NEC world). Read NEC 110.14(C)regarding the temperature limitations.

For sizing conductor's overcurrent protection look up Article 240 and also the ones related to panelboards. (Search for panelboards and switchboards in NEC).

Rafiq Bulsara
http://www.srengineersct.com

RE: ampacity?

You need to size your cable according to the upstream breaker protecting it.  Therefore a cable rated for 70 Amps or more is adequate.  

What is the length of the cable?  Voltage drop could be an issue with long lines (although in this case it sounds like you are ok).  Also will this be run in conduit?   

------------------------------------------------------------------------
If it is broken, fix it.  If it isn't broken, I'll soon fix that.

RE: ampacity?

(OP)
thank you TurbineGen and others for the responses. there shouldn,t be a problem with Vdrop, the circui is very short.
Thanks again all!! Have a great holiday season!
designered

RE: ampacity?

Need I remind everyone that code advice for DIY homeowners is highly discouraged here? This forum is for engineers, all of which, if identified as EEs, should not have to ask that question.


"If I had eight hours to chop down a tree, I'd spend six sharpening my axe." -- Abraham Lincoln  
For the best use of Eng-Tips, please click here -> FAQ731-376: Eng-Tips.com Forum Policies  

RE: ampacity?

That is very true. Don't try it at home! Or in anyone's home.

Gunnar Englund
www.gke.org
--------------------------------------
100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...

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