Electrical Service Question

[grsthegreat]

OK guys lets back up a bit.. The OP says he has a 200 amp disc. going to a 100amp panel hmm... better to start with that problem before anything else..:confused2:

That parts a little confusing. Ive seen 200 amp disconnects with multiple breakers (say 100 amp) to feed other buildings. Im not sure how a 200 amp disconnect can feed a 100 amp lug. unless he means a 200 amp lug?

its soo easy to get off course on these chat rooms.

 

[955Lincoln]

OK guys lets back up a bit.. The OP says he has a 200 amp disc. going to a 100amp panel hmm... better to start with that problem before anything else..:confused2:

If the wiring going to the 100 amp panel is sized for 200 amps would there still be a problem?

I'm curious because I may end up with this scenario depending on placement of future buildings.

 

[tommu56]

If the wiring going to the 100 amp panel is sized for 200 amps would there still be a problem?

I'm curious because I may end up with this scenario depending on placement of future buildings.

You can over wire the panel but it has to have protection = main breaker in the sub panel to limit the current in the panel to 100a.
This also means the correct lugs on the main breaker to take the 200a wire some times they won't.
You cant trim the wires to fit the lugs because you are reducing the capicity of the wire and wire has a ring effect = more current travels on the outside of the wire than the center and when people trim wires guess what ones get trimmed first. there are transition crimp lugs that cam be used to change size at sub panel.

larger wire sizes are done for long runs to minimize voltage drops.

tom

 

[Believer]

Oops. I left out an important part when I originally started the thread. Let me try again.

At the utility pole. Meter wires to a 200 amp disconnect. I will be wiring from the 200 amp disconnect to a 200 amp main lug on the utility pole, so just a couple feet of wire. In that main lug, I'll have circuit protection for the feeder to the house.

From that main lug on the utility pole, I need to go underground 200 feed to the 100 amp main lug on the house. I wasn't planning to have a main breaker at the house (old house we use as a cabin really). I don't really need 100 amps, probably 50 would be fine, but the 100 main lug was really all I could find at Home Depot that had enough circuits. I'm trying to figure out what specification of wiere, CU or AL, and whether I should direct bury or run in conduit.

At a later date, I will run another feed from the main lug on the utility pole out to the barn.

 

[955Lincoln]

Oops. I left out an important part when I originally started the thread. Let me try again.

At the utility pole. Meter wires to a 200 amp disconnect. I will be wiring from the 200 amp disconnect to a 200 amp main lug on the utility pole, so just a couple feet of wire. In that main lug, I'll have circuit protection for the feeder to the house.

From that main lug on the utility pole, I need to go underground 200 feed to the 100 amp main lug on the house. I wasn't planning to have a main breaker at the house (old house we use as a cabin really). I don't really need 100 amps, probably 50 would be fine, but the 100 main lug was really all I could find at Home Depot that had enough circuits. I'm trying to figure out what specification of wiere, CU or AL, and whether I should direct bury or run in conduit.

At a later date, I will run another feed from the main lug on the utility pole out to the barn.

Have you bought your meter socket yet or does the utility company supply it? The reason I ask is there is a panel called a meter main. It contains the meter socket and main breaker in the same enclosure. It also has spaces for a few more additional breakers just like a breaker panel would.

 

[955Lincoln]

You can over wire the panel but it has to have protection = main breaker in the sub panel to limit the current in the panel to 100a.
This also means the correct lugs on the main breaker to take the 200a wire some times they won't.
You cant trim the wires to fit the lugs because you are reducing the capicity of the wire and wire has a ring effect = more current travels on the outside of the wire than the center and when people trim wires guess what ones get trimmed first. there are transition crimp lugs that cam be used to change size at sub panel.

larger wire sizes are done for long runs to minimize voltage drops.

tom

Thanks for answering my over wire question. The larger wires would be terminated in a properly sized disconnect for a future building before reaching the 100 amp panel so no need for wire trimming.

 

[hr3]

If the wiring going to the 100 amp panel is sized for 200 amps would there still be a problem?

I'm curious because I may end up with this scenario depending on placement of future buildings.

If the breaker in your disconnect that is after the meter is 200 amp and panel that it is feeding is rated for 100 amps then yes you have a problem.. The wire size as you have been told has nothing to do with it,, It is common to use bigger sized wire to overcome voltage drop..

There is a very simple solution to your problem if all you need is 100 amps in your house...

 

[grsthegreat]

If the main breaker on the meter pole is 200 amps, then you HAVE to supply wire off of it that can carry 200 amps (ie: 4/0 alum or 2/0 copper). If however you can downsize the breaker at the meter pole to 100 amps, then you can size the wire to the house accordingly (#1 or #2 alum.) Mind you if you plan on running 200 amps to a future house than you will need to run the heavier wire now. You cant simply install a 100 amp panel in the house and say its protected to only 100 amps if its being fed from a 200 amp breaker. It doesnt work that way. You size the wire according to the breaker that supplies the load.

That being said, you HAVE TO have a main breaker panel at the house. you cannot use a main lug panel (legally) unless its within the same building that houses the main breaker panel (ie: a subpanel). iF YOU PLAN ON REBUILDING AT A LATER DATE AND INSTALLING A 200 AMp service, than install a 200 amp main breaker panel at this time, and you can re-use it on the new house. If the job isnt being inspected....then i guess you can do what you want with regards to the panel, but your insurance wont cover you if theres a fire.

 

[Lineman North Florida]

Oops. I left out an important part when I originally started the thread. Let me try again.

At the utility pole. Meter wires to a 200 amp disconnect. I will be wiring from the 200 amp disconnect to a 200 amp main lug on the utility pole, so just a couple feet of wire. In that main lug, I'll have circuit protection for the feeder to the house.

From that main lug on the utility pole, I need to go underground 200 feed to the 100 amp main lug on the house. I wasn't planning to have a main breaker at the house (old house we use as a cabin really). I don't really need 100 amps, probably 50 would be fine, but the 100 main lug was really all I could find at Home Depot that had enough circuits. I'm trying to figure out what specification of wiere, CU or AL, and whether I should direct bury or run in conduit.

At a later date, I will run another feed from the main lug on the utility pole out to the barn.

Whatever you decide, do yourself and anyone who comes along behind you a BIG favor and bury your service in conduit.:thumbsup:

 

[Believer]

OK, I need a main breaker in the subpanel at the house. Someone mentioned I had a problem on the utility pole. On the utility pole, I have the meter and 200 amp disconnect. I will wire from the 200 amp disconnect to a 200 amp main lug using a wire with the correct ampacity--no problem here is there? In the main lug I will install circuit protection for the feeder to the house. What type of wire should I use from the main lug on the utility pole to the house? Thanks.