Using 90 degree table for part of circuit?

[Twoskinsoneman]

Another gem from the MH NEC DVDs I'd like to get opinions on. One of the guys on MH's little panel said the following would be compliant.

Run a circuit using 90 degree wire to a 90 splice (and use it as the ampacity listed in the 90 degree column) and then from the splice run wire with ampacity from 75 degree column to 75 degree rated equip. (or 60 degree depanding on situation)

Does anyone consider it a violation if the wire using in the 90 degree portion of circuit would be undersized if used as the 75 or 60?

If this is so I think we could be saving a lot of money on longer runs of larger size wire

 

[iwire]

Yes you can do that, I think there is even a drawing around the forum from Square D that shows doing it. I also made my own before seeing the Square D one.

That said, it will only be worth the price of the extra boxes and splices if the run is long and if the run is long then voltage drop becomes an issue and the last thing that you would want to do is decrease wire sizes.

It strikes me that this would be more of a benefit at high voltages as voltage drop as a percentage becomes less of an issue.

 

[Twoskinsoneman]

Yes you can do that, I think there is even a drawing around the forum from Square D that shows doing it. I also made my own before seeing the Square D one.

That said, it will only be worth the price of the extra boxes and splices if the run is long and if the run is long then voltage drop becomes an issue and the last thing that you would want to do is decrease wire sizes.

It strikes me that this would be more of a benefit at high voltages as voltage drop as a percentage becomes less of an issue.

Very cool. Thanks.
I guess start thinking about extra boxes and voltage drop... aw bummer.

 

[celtic]

Give this a read:
The Middle Of The Wire Isn't Its End