10/3 or 10/2 for dedicated circuit?

I assume 10/2 correct?

I added six 20-amp branch circuits using 10/3 with a ground and used dual voltage outlets so I have 120VAC and 240VAC at the same outlets. My audio gear manuals state that the best performance is achieved using 240VAC. All of my amplifiers have 20-amp fuses in the chassis. If you are going to add branch circuits and your audio gear can operate on 240VAC, spend the extra money for the 10/3 wire because the labor is going to be about the same whether you go with 10/3 with a ground or 10/2 with a ground. I used Leviton 5842 outlets which are legal per the NEC and legal in my area.

My branch circuit runs are 80 feet and the voltage drop calculated using 125VAC at 20 amps is 2.7%. NEC requires a voltage drop of no more that 3%. Voltage drop is higher when you calculate using 125VAC instead of 240VAC. The 240VAC voltage drop is only 1.4%. 12 AWG at 125VAC and 20 amps would have given me 4.4% voltage drop therefore I had to use 10 AWG.

5842-I (leviton.com)

Here is a picture of four dual voltage outlets, I could not find them in white at the time, ivory was the only color.

I’m not up to speed with US code.

Here in the UK, 10 gauge is 2.5mm2 close to 6mm2 and the correct cable diameter quite large for dedicated circuit.

We refer to 10/2 as twin & earth, single conductor, neutral and earth/ground.

10/3 to us is referred as triple and earth, 2 conductors, neutral and earth/ground.

We wouldn’t use a 10/3 (triple+earth) here in the UK for dual voltage. To be fair we don’t use 120vac.

Using 240v means things pull less amps, and some consider this safer. Not debating which is best :wink:. But less amps means less heat. Which could mean longer lifespan, better SQ :man_shrugging:

A dedicated circuit, a radial circuit would be ok. Here in the UK this would be protected with a 20amp MCB/breaker/fuse. Depends on your load, future load.

I have recently had an extension made for and installed a dedicated circuit for it. It was a ring main though.

Edit: I made an error above. 10AWG is near 6mm2 :man_facepalming:

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I’m in the US so we have 120. I’m going to run a dedicated line/circuit for each piece of gear.

That is a great decision. Before I ran dedicated branch circuits, my family room lights and bedroom lights dimmed with the bass, and I occasionally tripped circuit breakers. Make sure you do the voltage drop math and abide by it. My AHJ told me I was crazy running 10 AWG, he said 12 AWG would be good enough. I disagreed and ran 10 AWG because the math said 12 AWG was too small. Whether you use 125VAC or 240VAC, do it right once and be done with it. You will have no regrets. Enjoy your new branch circuits.

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I often forget all of these forums are global :man_facepalming:

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