electrical question more of a code ?

spidermonkey · Sep 11, 2012

I know this is not really the place to ask this but I have been looking and looking in the code book and I have found nothing.

I have a guy I work with that likes to tie different size wires in to existing curcuits. I need to find a code to say that you can't do this

keithkyll · Sep 11, 2012

Not sure what you're looking for. I suspect it would be under UL508a. Try this link.

leitmotif · Sep 11, 2012

Per NEC ie USA code all conductors must have ampacity equal to or greater than protection ie fuse or breaker.

In very long wire runs to minimize voltage drop larger conductor is required. A 1000 foot run for a 16 amp load would require 20 amp fuses and normally a #12 conductor (nominally) - however because of length #10 or #8 may be required.

There is an exception for feeders but that is another thing and not appropriate to this question I think.

You can always use larger wire than required of course BUT never smaller.

Dan Bentler

Lancie1 · Sep 11, 2012

I have a guy I work with that likes to tie different size wires in to existing curcuits. I need to find a code to say that you can't do this

You probably will not find a code that specifically prohibits using different sizes of wires. The truth is that wires can and are made different sizes for different reasons, such as voltage losses over long distances. Sometimes a company or vendor does not stock certain sizes, so the next largest size has to be used. Going larger than needed to handle the load on the wire is almost always accepted by codes (an exception that comes to mind is the max size that can be connected to a ground rod). Going smaller is not.

mvaughan · Sep 11, 2012

If you are looking for a code reference to minimum size and ampacity try:

210.19 Branch-Circuit Ratings

I have one of those guys working for me, also. "Whats wrong with that, it works doesn't it"

James Mcquade · Sep 11, 2012

I have found a very good source is www.mikeholt.com
its an electrical website with as many helpful people as this site.

regards,
james

Mickey · Sep 11, 2012

James Mcquade said:
I have found a very good source is www.mikeholt.com
its an electrical website with as many helpful people as this site.

regards,
james

See link.

http://forums.mikeholt.com/showthread.php?t=83149

George Graziano · Sep 11, 2012

You may have to give a little bit more info. Do you mean 2 different size wires terminated together? Maybe into a terminal block or lug?
George

dogleg43 · Sep 11, 2012

The CB or fuse rating must be greater than or equal to the smallest wire size in the circuit.

I can't quote the NEC section from memory but look under branch circuit overcurrent protection, maybe art 230or 240.

electrical question more of a code ?

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