Sub panel wiring

[juptonstone]

SER not SE

SER not SE

I am relatively new to electrical contracting and I am doing my first residential basement finishing project installing a 100A sub panel to feed the load. I am wanting to install SE wire from the main to the sub panel. I have looked in 338.10 for installation requirements. In 338.10(A)(4)(a) it points me back to part II of 334.

My total load is only 51A. My questions are:

1) Is #4 SE cable overkill for this installation? It is 70' of wire and voltage drop looks good.
2) 334.10 seems to say I do not have to install it in conduit. Is that correct?

I appreciate any responses because I just want to make sure I get this to code with no issues.

Varczar

If you are installing a 100 amp sub panel, I do not care what you are tying into it right now... I really suspect that the inspector will say it has to have the capacity to carry a total load of 100 amps... so that's either #4 copper, or #2 aluminum SER. SE has three wires... SER has 4... anytime you install a sub panel, the ground must be connected to the box and the neutral must be isolated from the ground. Remember to add a separate ground bar if the box doesn't have a second one built in. and remove the ground tab from the neutral bar (if it comes built in).

 

[augie47]

If you are installing a 100 amp sub panel, I do not care what you are tying into it right now... I really suspect that the inspector will say it has to have the capacity to carry a total load of 100 amps...

may be true in your area, but not here. The load would determine the feeder size. I see a lot of 100 amp panels with 60 amp feeders. If you or the customer want load diversification, almost any panel over 8 or 12 circuits will be bigger than 60 amps.

so that's either #4 copper, or #2 aluminum SER.

under the '08 Code, SE (SER) would only be #4 SE would be 70 amps and #2 SE AL would be 75. Neither would be 100.

SE has three wires... SER has 4... anytime you install a sub panel, the ground must be connected to the box and the neutral must be isolated from the ground. Remember to add a separate ground bar if the box doesn't have a second one built in. and remove the ground tab from the neutral bar (if it comes built in).