Sub Panel questions.

[BlackKnight427]

Hey guys I have a few questions for you that have either installed or have had a sub panel installed.

I guess my first question is how high of an amperage breaker would be recommended or how would I calculate for one? the garage is 22x24 it will have a pretty decent sized compressor (amperage rating on compressor is 22amps it has a 5hp motor) a tig welder, lift, fridge, and some lights maybe like 8 florescent fixtures along with some outlets I'm thinking 8-10 outlets.

The panel in the house says it only has 100 amp mains, so Im assuming I cant or shouldn't try for a sub panel that has too high of a rating.

I was told that I may be able to upgrade my panel in the house and get a higher amperage service in order to get more available amps out to the garage sub panel, Have any of you ever done something like that?

How involved was it and could you give me an idea of what something like that may run? I would just like a ball park, for example would it run a few hundred (2-300) to a few thousand (1500-3500)?

 

[p_mori7]

Don't know about cost of changing the panel, I already had a 200A service.

I installed a 100A breaker and wired a 100A subpanel in my detached garage 80' of run.

The breaker, the copper bury rated wire (armored mine wire), LB's, elbows, sections of conduit, the subpanel itself, the breakers in the subpanel, ground rod, trencher rental...all was about $1000 CDN.

I did the install myself.

 

[wyliesdiesels]

If this is a one man shop, 60-90a would be plenty! U could run #2 AL MHF(mobile home feeder) and protect it with upto a 90a breaker in the main service panel. In your subpanel, u might want a main disconnect in case u need to shut the panel off and one is required if there is more than six breaker handles!

And u could put more than 100 amps worth of breakers in your main because not verything is on at the same time AND most circuits dont consume the full ampacity of the breaker protecting the circuit!

As far as cost goes, that can vary widely from region to region and how u go about the install(cu or al, number of circuits, trenching method, self install or professional, etc, etc.). And I am assuming that this garage is detached!

 

[BlackKnight427]

If this is a one man shop, 60-90a would be plenty!

It will be for the most part, at some point I know one or two friends will find their way over to give me a hand. I'm just concerned about splitting 100 amps between both a garage that will have a decent amount of usage and the house.

 

[Gerald O]

You may be able to split the service at the meter base to feed a second main panel for the garage and keep the existing one for the house as-is. Might be cheaper than installing a bigger main just to feed a subpanel. You can check with your power company to see what the incoming service will handle.

 

[brewchief]

Is the garage attached or detached?

I would install a 100 amp subpanel with plenty of spaces, something with 20 or so spaces should be plenty.

I would probably feed it with wire that could handle the full 100 amps or at least close( 90amps is pretty common due to wire sizing).

Upgrading the house panel will depend on how much load there is on it currently, if the house has an electric water heater, dryer, range and A/C or a heatpump with electric backup heat then it very well could be maxed out right now, if everything is gas and it's mostly just lighting loads then you might be just fine as is.

Cost can vary a LOT, adding a subpanel to an attached garage 10 feet from the main panel is a lot different then running 100's of feet of wire to a remote detached garage.

 

[Charles (in GA)]

It is OK to use a subpanel that is rated at a higher amperage than what you are supplying it ie. 125 amp 20 space panel, fed by a 90 amp breaker in the old main panel and 2-2-2-4 AL wire.

It is NOT OK to use a subpanel rated for say, 60 amps being protected by a breaker of a higher amperage.

Match the supply breaker in your house panel and the wire supplying the garage, then use a panel with MORE THAN ENOUGH breaker spaces in the garage.

Don't worry about having a large panel with a supply breaker that nearly equals the house panel in amps, you won't be using all of it at once, and the house main will protect everything if in the odd chance you do overload it.

The purpose of the large panel in the garage is more to have working space inside it for proper and neat wiring, and being able to split up circuits for better control of them, along with future additions of power hungry stationary tools. If you don't use it, someone in the future will appreciate it.

Charles

 

[wyliesdiesels]

It will be for the most part, at some point I know one or two friends will find their way over to give me a hand. I'm just concerned about splitting 100 amps between both a garage that will have a decent amount of usage and the house.

If u dont have the electric items mentioned by brewchief, then u should do fine. With it being mostly a one man shop, theres NO way u could pull 100a continous!

 

[Falcon67]

Our old house had a 150A panel and I used 60A to feed the shop, with more stuff out there than you have. No issues or trips ever. My new shop is double the size with two AC units plus all the other electrical stuff and even more lights. It's on a 70A breaker at the house with a 125A 20 slot panel in the shop. No trips.

 

[BlackKnight427]

Don't worry about having a large panel with a supply breaker that nearly equals the house panel in amps, you won't be using all of it at once, and the house main will protect everything if in the odd chance you do overload it.

Thank you that is exactly what I was wondering and what I was hoping to do.

The purpose of the large panel in the garage is more to have working space inside it for proper and neat wiring

Just like you said I figure the more room I can give myself the better to work in there plus if I ever end up upgrading my service and end up needing more amps I will already have the panel/room and space.