romex with low voltage
- Thread starter davel
- Start date
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Volta
Senior Member
- Location
- Columbus, Ohio
I think it is ok.
300 watts / 24 volts = 12.5 amps
12.5 * 1.25 (for continuous) = 15.63 amps 210.20(A).
NM-B conductors rated at 90 deg C, ampacity is 25. Section 110.14(C) allows that application.
411.5(D) allows for Chapter 3 methods.
- Location
- New Jersey
- Occupation
- Journeyman Electrician
For a continuous load I would say no. You're limited to 15 amps maximum by 240.4(D).
Volta
Senior Member
- Location
- Columbus, Ohio
Well, true if the secondary has OCP. Good point.
- Location
- Massachusetts
Just wondering how long of a run this is?
Bet you will have excessive voltage drop unless it is very short.
Bet you will have excessive voltage drop unless it is very short.
- Location
- Massachusetts
You will end up with more than 6% voltage drop or 22.5 Volts at the fixture.
This may be fine the lamp will last longer, but the customer may not be happy with the light output.
You would need 10 AWG to keep it under 3% drop.
Volta
Senior Member
- Location
- Columbus, Ohio
Overcurrent protection on the secondary of the transformer? Primary?
- Location
- Massachusetts
There has to be secondary overcurrent protection.
Volta
Senior Member
- Location
- Columbus, Ohio
Then as Rob showed you either have OCP of 15 amps, and too small for a continuous load, or OCP of 20, too large for the 14 awg.
- Location
- New Jersey
- Occupation
- Journeyman Electrician
- Location
- Chapel Hill, NC
- Occupation
- Retired Electrical Contractor
Generally speaking I would not go near 14 gauge wire for low voltage esp. at 300 watts. It does not take long for VD, as Bob stated, to take effect. I use #12 awg at the smallest and have used as large as #8 for long runs and high wattage.
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