Feeding 150 amp panel from 200

Status
Not open for further replies.
Z

zcanyonboltz

Senior Member
Location
denver
My buddy is doing a service change on a house and then wiring an addition does anyone see a problem with feeding a 150 amp panel from a two hundred amp panel? I don't know the load calculation on the addition but it will have a welder, dryer and an RV receptacle and a well pump and then some general lighting and receptacle circuits. I recommended a 125 amp panel at the addition fed with 1/0 SER and then run 2/0 to it in case a 150 is necessary. I can't think of any code violations or problems with feeding a 150 amp panel from a two hundred amp panel but this isn't very common just wanted some opinions thank you.
 
Z

zcanyonboltz

Senior Member
Location
denver
zcanyonboltz said:
My buddy is doing a service change on a house and then wiring an addition does anyone see a problem with feeding a 150 amp panel from a two hundred amp panel? I don't know the load calculation on the addition but it will have a welder, dryer and an RV receptacle and a well pump and then some general lighting and receptacle circuits. I recommended a 125 amp panel at the addition fed with 1/0 SER and then run 2/0 to it in case a 150 is necessary. I can't think of any code violations or problems with feeding a 150 amp panel from a two hundred amp panel but this isn't very common just wanted some opinions thank you.
Click to expand...

Just looked at table 310 15 B 16 and realized my wire size numbers are off in my original post since the sub panel will be fed from the main panel and not seeing the entire load of the dwelling unit the wire size would need to increase to 2/0 aluminum for the 125 amp panel and then 3/0 aluminum if a 150 amp sub panel, since table 310 15 B7 can't be applied to a sub panel.
 
Z

zcanyonboltz

Senior Member
Location
denver
480sparky said:
Can you even get a 150a breaker that will fit on the busbars?
Click to expand...

I have bought a 150 amp GE breaker it took up two full size breaker spaces on each phase but it fit in the GE panel the breaker is hard to find I had to go to the used breaker Supply House the guy only had two of them and if I remember right it was a hundred fifty bucks.
 
Sierrasparky

Sierrasparky

Senior Member
Location
USA
Occupation
Electrician ,contractor
It will be a quad breaker , However the panel you use may not allow it. you need to look at wire bending space too. If it is a all in one that is only 14 1/2 " wide you won't have a lot of bending space.
 
Z

zcanyonboltz

Senior Member
Location
denver
Thanks for the replies. The conclusion is 125 amp feeder to the addition then if needed just put a subpanel next to the 125 amp panel for the general lighting and receptacles circuits if needed. One of the issues he is having is the homeowners aren't sure what all they want in the addition like air compressor, welder size , possible hot tub.... but the feed to the addition needs to be completed now why they have that part of the house opend up.
 
480sparky

480sparky

Senior Member
Location
Iowegia
I've had my fill of "I don't know what I want right now", followed by "Gee, this is getting expensive" once they decide.... after cheaping out at the outset. Suggest a new 400a service. A pair of 200a panels and call it a day.
 
kwired

kwired

Electron manager
Location
NE Nebraska
LarryFine said:
Agreed. Don't supply the addition panel from the house panel.
Click to expand...
Or at least arrange it so it is easier to convert if needed. Probably only supply it with a 100 amp breaker for now, I don't know about GE, Sq D 125 amp breakers take a price jump over 100's, and those 150-225 that take four spaces take another price jump.
 
LarryFine

LarryFine

Master Electrician Electric Contractor Richmond VA
Location
Henrico County, VA
Occupation
Electrical Contractor
zcanyonboltz said:
Just curious what your thoughts are for not supplying the addition from the existing house panel?
Click to expand...
In no particular order:

Why use (or add) 3/4 of a panel's capacity to feed another panel? Just feed that other panel from the same source; i.e., a 400a meter base.

The cost of such a large breaker will be almost that of a separate disconnect, without the advantages of an independent feeder and panel.

The cascading of equipment to supply what will be the majority of the total load just doesn't make sense to me. Run two independent feeders.

Of course, we don't know the calculated load on the 200a panel, but if there's 150a worth of overhead, it's way oversize without the add-on.
 
Chamuit

Chamuit

Grumpy Old Man
Location
Texas
Occupation
Electrician
Why not have a 200A feed through panel?

In some of the older parts of Phoenix, the service hits the detached garage before heading to the house. I used to put a 200A pump panel on the garage then feed the house with whatever I calculated. If it was a 3-phase panel, I'd take the AC condenser circuit along with the house feeder in a separate conduit.

Just a thought.
 
electrofelon

electrofelon

Senior Member
Location
Cherry Valley NY, Seattle, WA
jeff48356 said:
Yes, my thoughts exactly. Maximum feeder size for a sub panel is 125 amps. Kind of an unwritten Code rule. No need to write it because they don't make parts that allow anything larger to be used.
Click to expand...

Most (all?) manufacturers make 150-235 amp stab breakers. They are rather pricey and take up 4 spaces.
I think it's more that anything over 125 is almost always not needed. 99% of houses would be fine with a 100 amp service.
 
Z

zcanyonboltz

Senior Member
Location
denver
I will get the numbers and do the exact load calculation with him and update. Feed through panel seems like a good idea we used to have a job site where the 200a panel is mounted on the garage then fed through underground to the house. The local inspector would not let us derate the conductor size to 83% of main breaker size because at the garage we would power the garage, she told us that when the conductors got to the house they were not seeing the entire load of the house because they picked up the garage first. I know that's not a factor in this case because the sub panel would be less than 200 just thought I'd post that.
 
Status
Not open for further replies.
Top