2" conduit and subpanels

A.W.Davis

First off a huge happy Thanksgiving to all of you. Be safe over the holidays.

Okay with that being said.....I am trading work for some family friends and helping out with electrical on there new detached 1700 sqaure foot 4 bedroom unit theyare building on there lot.

So heres a few questions hopefully somebody can help me with that will help me out a ton.

1) The blue prints suggest a 125 amp panel located anywhere the contractor requests, power will be pulled from main house service panel......my question is, can I just run my feeds to an interior subpanel on the new unit, or do I need an exterior service shutoff at the new unit, then jump to a subpanel inside??

2) My next question is (brace yourself) haahaha.......can you make knockout holes larger on a 125 service to accept 2" conduit, I am needing to run 4 2/0 stranded wires to the new panel of the unit, and 2" conduit is what I calculated on what I would need.

I think thats it for now.......thanks guys

Speedy Petey

I am very confused by #1. Is there an existing panel? Or is this all new?
You keep saying "unit". Is this a condo or something like that? Is there an existing service somewhere else that you will be pulling from?

#2 - Yes, you can make the knockout larger. You will need a punch or hole saw though. I will say, a hole saw is a huge PIA to use to make a hole larger.
I must ask. Why do you "need" to run four 2/0???

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Sometimes I feel like if I answer any more questions it is like someone trying to climb over a fence to jump off a bridge and me giving them a boost.

A.W.Davis

.....its basically a 4 bedroom 2 bath house without a kitchen, so I guess you would just call it a detached addition.

I am pulling power from the existing house service to the new addition as per plans. Whats confusing me is if I need a service shutoff on the outside of the new addition or is the main house service good enough. I have been looking through my NEC book and cant find any referances. New construction is new to me......99% of my work are remodels where everything is there for you already.

And as far as the wires.......I dont really have to run (4) 2/0 wires......I was just wanting to oversize the wiring for possible future upgrades since all the wires will be ran in conduit, the next guy wont have to pull larger wires. I know my ground doesnt have to be a 2/0 also, my 2/0 feeds will be ran roughly 150' from the main house to the new addition so I was worried about voltage drop. Whats your thoughts on running 2/0 on a double pole 100 amp breaker.... everything seem legit?

Sparky Joe

I don't think 2/0 will fit in a 125 amp breaker.

And you don't need a main disconnect, just a regular 125 amp panel inside(or whatever size you choose), just make sure it's not a "load center"

Speedy Petey

You do need a main disconnect for this building, even though it is fed from an existing service. This can be a main breaker panel if it is close enough to where the feeder enters the building.


Joe, I don't get your "load center" comment. Can you explain?

__________________
Sometimes I feel like if I answer any more questions it is like someone trying to climb over a fence to jump off a bridge and me giving them a boost.