Question regarding wiring.

[Rob Russell]

For a 240v/50A subpanel, #6 NM cable is fine. You need 6/3-NM, which gives you 3 insulated conductors - black, red, white plus the uninsulated bare copper equipment grounding conductor.

Rob
Addy protocol: unlicensed, homeowner electrician

[Gary Lange]

Thinks about down the road when you want more power I would run a separate 100amp service to your workshop and then run your circuits for the shop off this. It is easier to do it big the first time and have all you will need then to have to go back and do it again because your needs have increased. It is the old measure twice and cut once deal. It will cost no more or maybe only a little more to run the 100amp service over the 50amp service.

[Rob Russell]

The biggest difference with the 100 amp subpanel is that the conductors have to be a lot larger. I checked prices on stuff recently though, and it was cheaper to run the aluminum conductors that you'd want to use for a 100 amp panel than it was to run copper for a 60 amp panel.

[Kyle Costlow]

What kind of wire does the 100 amp breaker need. I have to run about 60-75 feet of it and the 6/3 stuff is expensive enough.... I wont be living in my parents house forever so I think 50 amps will do for now, when I get my own house, I might get a 200 amp panel for the shop

Question.. Does the panel rating mean that it can supply that much amperage at the same time?

[Kyle Costlow]

The biggest difference with the 100 amp subpanel is that the conductors have to be a lot larger. I checked prices on stuff recently though, and it was cheaper to run the aluminum conductors that you'd want to use for a 100 amp panel than it was to run copper for a 60 amp panel.

(wow you really know your stuff)
Can you explain what I would need for the 100 amp panel(I was thinking of using a 100 amp panel fed by a 50 amp breaker.) Whats the most cost effective way, while remaining safe?

[Rob Russell]

Kyle,

Unless you really need 100 amps @ 240v, I wouldn't recommend trying to put in a 100A circuit. The conductors you'd need are big and stiff to work with.

If you really want to put in something that will give you all the capacity you're ever likely to need, put in a 60 or 75 amp subpanel. Run #2 aluminum SER. The #2 aluminum SER is good for 75 amps. At the local Home Depot, it's $1.92/foot. FYI, the #2 SER is going to enough to work with. You'd need 1/0 aluminum SER if you wanted a 100 amp subpanel and that's just not something I'd want to work with. If I needed it, I'd run conduit and pull #3 copper or #1 aluminum individual conductors.

There are locales that will allow you to use the #2 SER for a 100 amp subpanel, but I personally think that's misinterpreting the code. It's their call to make, though.

As a cost comparison, #6-3 copper NM cable is only good for 55 amps and costs $2.62/foot because copper has gone up so much.

Anyway - as I said above in this post - if you really want the juice - go with the #2 aluminum SER and either a 60 or 75 amp breaker. The chances of your ever needing more than 40 amps @ 240v are probably slim, but if you want the extra capacity - go for it.

You can put in a panelboard that's rated for 100 amps and only feed it with 60 or 75 amps - that's fine.

Make sure that you get a panelboard with an isolated neutral. I'd also recommend having neutral and equipment grounding conductor rails on both sides - it makes the wiring easier to keep neat.

Rob
Addy protocol: unlicensed, homeowner electrician

[Joe D'Attilio]

Kyle,

Unless you really need 100 amps @ 240v, I wouldn't recommend trying to put in a 100A circuit. The conductors you'd need are big and stiff to work with. etc....

Rob, can you just come over sometime?

[Rob Russell]

Rob, can you just come over sometime?

Sure - put up some great food, super wine - I'll bring the wife so she's happy too.

Only thing is ... I can't do wiring in your house ... just watch.