garage electric pannel

[curbshopper]

the garage i just tore down to build a new bigger garage had a 100 amp box with a main shutoff, it was fed by a 100 amp breaker in my 200 amp service in my home. this was in the home when we purchased. the wire size to it was appropriate to feed that box, but is this the way it should be done ? I found a 16 place box with no main breaker shut off very reasonable, is at acceptable to feed that box with the line currently going there from the breaker in the house box. Do i want to have a main breaker in the garage ? What is the best way to feed the garage box? is 100 amp enough, i don"t do any heavy duty stuff. thanks

 

[pgray007]

This is just about exactly the setup I had/have. Apparently you don’t need a disconnect at the sub panel until you exceed a certain number of breakers (6 if memory serves) after which point you add a disconnect.

Depending on what you do, 100A May or may not be fine. It’s worked for me with a shop and finished room above, but it sounds like whatever you’ve got is correct and might just need the addition of a main disconnect at the sub panel once you start loading the sub panel up. If it does, it’s about a 8 min job to add one, including 4 minutes of cursing since you can’t find the right tools, and 45 seconds to get the celebratory beer when complete.


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[Norcal]

Is the garage detached or attached? It does make a difference.

 

[pattenp]

Is the existing feeder 3 or 4 wires? It needs to be 4 to meet code. You need to verify wire type and gauge to be sure it's good for 100A. Is it an underground feed?

 

[curbshopper]

detached garage , 4 wire and an underground wire feed

 

[wyliesdiesels]

What gauge wire?

 

[curbshopper]

i need to refresh my memory tomorrow on the guage

 

[curbshopper]

wire to garage is copper, 6-3 with ground, underground cable, is this suitable for 200 amp service, if i choose to go bigger than a 100 amp service in garage. is it better to go that big "just "in case, donot want to redo again

 

[jim111]

Depends on exactly what kind of cable it is, what does the jacket say? No way it's good for as much as 100 amps

 

[wyliesdiesels]

wire to garage is copper, 6-3 with ground, underground cable, is this suitable for 200 amp service, if i choose to go bigger than a 100 amp service in garage. is it better to go that big "just "in case, donot want to redo again

Not only is #6 cu not good enough for 200a, its no where near large enough for 100a.

Is the outer jacket gray?

Someone way oversized that feeder.

#6 UF-b or NM-b has max ampacity of 55a.

 

[pattenp]

Actually #6 copper is 55A and can have a breaker up to 60A, but max load is not to exceed 55A. For 100A you need #3 copper or #1 aluminum. 200A is 3/0 copper or 250 kcmil aluminum. Also distance plays a part in wire size due to voltage drop.

 

[wyliesdiesels]

Actually #6 copper is 55A and can have a breaker up to 60A, but max load is not to exceed 55A. For 100A you need #3 copper or #1 aluminum. 200A is 3/0 copper or 250 kcmil aluminum. Also distance plays a part in wire size due to voltage drop.

Yeah whoops.

Brain fart.

 

[curbshopper]

yes ,grey outer jacket

 

[wyliesdiesels]

That would be UF-b.

Ampacity is what we said above.

Need larger wire if you want 100a.

 

[curbshopper]

So i know understand ,i think, the previous owner put in a substandard cable in the ground to feed the 100 amp box that was in the old garage. I need a 3 #copper to new garage, is aluminum ok for this purpose, for the cost element ? I am going about 30 feet. do i tie this into the home service. Sorry if these seem like basic questions, I know how to run stuff from the box, but i want the new box right to run from it ! Thanks

 

[wyliesdiesels]

What are your loads?

Do you really need 100a?

You may be able to go with #2 al which would give you 90a.

You would change the garage breaker in the main panel to 90a.

#2 al MHF is the best bang for the buck.

Can be direct buried but must be in conduit indoors. Conduit is recommended for entire run.

 

[curbshopper]

welder , air compressor, wood tools, small kitchen area , gas stove and water heater possibly to keep the amps down, Am i thinking too big for going 100 amp, i thought that was a good minimum to go with. thanks

 

[wyliesdiesels]

an electric water heater and stove would be too much coupled with the other equipment especially a welder.

Definitely go gas on everything you can.

One man shop?

What model welder and what size in HP compressor?

 

[75gmck25]

2-2-2-4 aluminium MHF is very often used, has a reasonable price, and its rated for 90 amps. You can buy dual rated MHF that can be used both for the underground feed, and for wiring inside the building (in conduit).

The MHF I found locally was not clearly marked as dual rated, and the big box store clerks had no idea what I meant. I ordered mine online from Wire and Cable Your Way. Their prices were good, but there was a minimum shipping cost of $25.

Bruce

 

[curbshopper]

actually i am only going with a 110 welder now, i have friends that weld better than me, we trade skills ! compressor is the 2hp ,would like standup one some day, i mainly wood working and car restoration hobbys, sounds like a 90 amp feed line could work, is the 60amp line realistically/box thinking too small

 

[pattenp]

If the existing 6/3UF is usable as installed, such as connected into the house main service panel and can be connected to a subpanel in the garage then just use it at 60A. That means feeding it from a 60A breaker at the house panel and installing at least a 100A main breaker panel in the garage. Providing you are not using electricity to heat or heat water you will probably find that 60A is enough. If you find out later that 60A is not enough then just replace the 6/3UF with larger wire and up the feeding breaker size accordingly.