Wiring question

[Rollie Meyers]

AL is fine but what type of cable? Quadplex?

[Rob Russell]

I may have it wrong but when I see 120/240 installs its usually in commercial applications. To this day I have not seen 240 in a residential installation.

But I am a commercial electrician and have done little residential aside from the service changes. And those were always 120/208.

So my assumption is the OP has a 120/208 system and was making a common mistake of thinking 2 x 120 makes 240. Well I guess it does but not in a Wye connected transformer.

And you can not add ground rods and make your own neutral in another panel. Neutrals are tied together in the main panel and any sub panel has the neutral buss isolated from the ground buss.

It's interesting that you've only seen 120/208 residential systems because the vast majority of US households are wired with 120/240 single phase systems.

Is it possible that the 3-phase systems you saw feeding residential panels were delta configuration and only used the 2 base legs, not the hot/wild leg?

[Richard Jones]

Anthony said...............

"And you can not add ground rods and make your own neutral in another panel. "

My F-I-L did this on a security light down near one of his barns, and it worked, but it sure ain't right. If you got close to it when it was damp and you had the wrong shoes on, it got real interesting when that light came on...................... He would have made a good carnie electrician.

Rich

[Rick Christopherson]

I was planning on running a 30A/220V , using 6 gauge 4 conductor wire.

I will have one 15A/120V circuit for 2 100watt incadescent bulbs and one 20A/120V circuit for one GFCI receptacle.

People tend to get a little carried away with voltage drop calculations. First off, it is based on the actual load, not on the circuit size. Secondly, there is no prescribed maximum voltage drop, and 3% is on the extreme side, especially for a pole barn.

Since the lighting and outlet are on separate phases you can ignore the lighting and focus on the expected load on the outlet. This should be about 15 amps. If you used copper, you could still use #10/3. If you go with aluminum, the #8/3. You will still be within 5%.