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I am running a new 20A circuit with 12 AWG wire to the exterior of my home and will be adding a flood light to the circuit.

All of the flood lights I have seen have 18AWG conductors in them. Is it OK if I connect them to a 12AWG wire on the 20A circuit?

The fixture has a 300 max wattage (150 W bulbs max a piece).

I am using 20A/12AWG because there will also be 2 receptacle on the circuit and I want enough power to run heavy equipment (Yard tools, electric grill, compressor, etc.) when necessary.

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up vote 3 down vote accepted

Most likely.

As long as the fixture has a UL (or equivalent) stamp/sticker, there is no problem.

Fixture wires, and the wiring inside devices is specifically designed to carry the rated loads. There are different rules applied in this situation, since the load is known and static.

According to the National Electrical Code 2014 402.5, the allowable ampacity of 18 AWG fixture wire is 6 amperes. Your fixture will only draw 2.5 amperes.

I = P/E = 300 Watts / 120 Volts = 2.5 Amperes

If the manufacturer could use smaller wires, they probably would. However, NEC says 18 AWG is the smallest allowed for fixture wires.

One of the reasons light socket adapters can be dangerous, is that they can allow more current to be drawn than was intended by the fixture manufacturer.

Light socket adapter

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