branch electric box question

wanting to feed a branch box with a 60a breaker (#6 copper) thru EMT.
This may be a stupid question, but is there anything in the NEC to prohibit using double #10's to get the amperage? Reason is I have plenty of (free) #10 on hand and tube capacity is slightly better with #10's.
thanks bill
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I guess derating would apply (6x 10ga THHN +8ga grounding) , in which case a 50a breaker may suffice?
bill

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Yes, there is. Section 310-4 explicitly *permits* parallelling conductors of size 1/0 or *larger*, and thus by implication prohibits it for smaller conductors.
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Doug Miller (alphageek at milmac dot com)
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bummer..
thanks doug
bill
wrote:

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Just wonder why parallel wires are permitted for #10 and lower and prohibited for smaller wire sizes?
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That is 1/0, not 10.
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i would imagine that the theory is that smaller wire sizes are too easy to tinker with regarding the clamping hardware at breakers, etc. If one of the parallel wires became disconnected, there could be a severe overload on the remaining conductor. Bill

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rider89 wrote:

310.4 Conductors in Parallel. Aluminum, copper-clad aluminum, or copper conductors of size 1/0 AWG and larger, comprising each phase, neutral, or grounded circuit conductor, shall be permitted to be connected in parallel (electrically joined at both ends to form a single conductor). copyright 2002 National Fire Protection Association.
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Does it not also say that _each_ conductor must be the same size, and each capable of carrying the full breaker current?
[Our code does.]
Which basically means you can parallel conductors to reduce end-to-end resistance (voltage drop), but NOT to increase circuit ampacity.
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On Tue, 23 Aug 2005 17:39:59 -0000, snipped-for-privacy@nortelnetworks.com (Chris Lewis) wrote:

No you add the ampacity of paralleled conductors but bear in mind they must be 1/0 or larger (about 10mm). The reason you can parallel conductors is to use a size that is more easily handled in large ampacity circuits.
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As I mentioned, _not_ in our code.
You can only parallel conductors to decrease voltage drop. The individual conductors must still be large enough to take the full ampacity.
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Chris Lewis, Una confibula non set est
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(Chris

What code do you operate under?
I can not imagine trying to pull a conductor for a 2000 amp service. We parallel conductors for load all of the time. It is not practical to use any conductor larger than 1000 circular mills. I just do not have the sand in the ass any more to handle wire that big. Commonly 750 mcm is the largest conductor used where I live.
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