Electrical gurus in here...

[greenbullitt]

Thinking of adding a second breaker box for the garage only. I currently have one open 220v spot in the existing box. my thought is to add one breaker here, a main breaker have you, to feed the second panel. my question is on amperages. how big of a main do i need if i want to run say a 20a 220v and a 60a 220v...possibly a 3rd also, but dont know how much i can run SAFELY. do i simply add the amperages together to figure the main breaker or is there more math than that involved...what can you truly run off the main breaker if feeding the sub panel with say a 4ga feed? I Would like to put some 110V outlets on this if possible, but not essential. 220v is my only true need.

thanks in advance!

<----home electrical idiot :)

[Thehead]

Thinking of adding a second breaker box for the garage only. I currently have one open 220v spot in the existing box. my thought is to add one breaker here, a main breaker have you, to feed the second panel. my question is on amperages. how big of a main do i need if i want to run say a 20a 220v and a 60a 220v...possibly a 3rd also, but dont know how much i can run SAFELY. do i simply add the amperages together to figure the main breaker or is there more math than that involved...what can you truly run off the main breaker if feeding the sub panel with say a 4ga feed? I Would like to put some 110V outlets on this if possible, but not essential. 220v is my only true need.

thanks in advance!

<----home electrical idiot :)

Paul, you need to talk to my father-in-law. he is going to be doing some of that at the new place. He might help you out. He is leaving today but will be back sunday evening.

[STANGGT40]

Thinking of adding a second breaker box for the garage only. I currently have one open 220v spot in the existing box. my thought is to add one breaker here, a main breaker have you, to feed the second panel. my question is on amperages. how big of a main do i need if i want to run say a 20a 220v and a 60a 220v...possibly a 3rd also, but dont know how much i can run SAFELY. do i simply add the amperages together to figure the main breaker or is there more math than that involved...what can you truly run off the main breaker if feeding the sub panel with say a 4ga feed? I Would like to put some 110V outlets on this if possible, but not essential. 220v is my only true need.

thanks in advance!

<----home electrical idiot :)

without over-complicating things, i'm going to say to just go with a 100A subpanel. go to home depot, get a 100 amp 2-pole breaker that fits your box and a 100 Amp MLO (main lug only) panel with the breakers that you need for whatever you're using. run either romex or pipe with thhn wire...#3 wire for your hot and neutral and a #8 or #6 for your ground. make sure and use separate neutral and ground bars in the sub-panel and do not bond them...they're already bonded at the main panel. (or should be) there ya go. :)

FYI: make sure to turn the main off when installing the breaker so the panel is dead (below the main) and leave the new breaker off until everything is complete and closed up.

if you decide that you don't want to do it yourself, i can give you the name and number to my residential service tech, and he can do it for you for a reasonable price.

[J&T's 82]

Thinking of adding a second breaker box for the garage only. I currently have one open 220v spot in the existing box. my thought is to add one breaker here, a main breaker have you, to feed the second panel. my question is on amperages. how big of a main do i need if i want to run say a 20a 220v and a 60a 220v...possibly a 3rd also, but dont know how much i can run SAFELY. do i simply add the amperages together to figure the main breaker or is there more math than that involved...what can you truly run off the main breaker if feeding the sub panel with say a 4ga feed? I Would like to put some 110V outlets on this if possible, but not essential. 220v is my only true need.

thanks in advance!

<----home electrical idiot :)

Sounds like you are wanting to run a compressor and stick welder. #4 THHN is good for 95 Amps. You don't figure amperage on what everything will pull because you won't be operating everything at the same time. The bigger question is how large is your existing service. If you are running the welder, while your AC is on and your wife is cooking and drying clothes then there could be an issue.

If you don't have any electrically experience my advise is to get an Electrician to come out and atleast set the subpanel and wire to the main. Hopefully you won't need a service change.

[greenbullitt]

Sounds like you are wanting to run a compressor and stick welder. #4 THHN is good for 95 Amps. You don't figure amperage on what everything will pull because you won't be operating everything at the same time. The bigger question is how large is your existing service. If you are running the welder, while your AC is on and your wife is cooking and drying clothes then there could be an issue.

If you don't have any electrically experience my advise is to get an Electrician to come out and atleast set the subpanel and wire to the main. Hopefully you won't need a service change.

the existing feed is way large, and wont run all at once anyhow, but yes..good point.
i have a basic knowledge of general electrics but was basically unsure of how to figure the main breaker load. sounds like ive got it down, thanks for the confirmation!

[greenbullitt]

without over-complicating things, i'm going to say to just go with a 100A subpanel. go to home depot, get a 100 amp 2-pole breaker that fits your box and a 100 Amp MLO (main lug only) panel with the breakers that you need for whatever you're using. run either romex or pipe with thhn wire...#3 wire for your hot and neutral and a #8 or #6 for your ground. make sure and use separate neutral and ground bars in the sub-panel and do not bond them...they're already bonded at the main panel. (or should be) there ya go. :)

FYI: make sure to turn the main off when installing the breaker so the panel is dead (below the main) and leave the new breaker off until everything is complete and closed up.

if you decide that you don't want to do it yourself, i can give you the name and number to my residential service tech, and he can do it for you for a reasonable price.


thanks for the details Brad !i think ive got it. sounds like a fun weekend. :)

[greenbullitt]

so i went and bought a panel and breakers tonight. i will get the wire in the am. lowes wasnt much help this time. this panel did not have a ground bar in it. i actually got a 125a since thats all they had that shared my other breakers currently in use (i just wont use it all)

just need to jump my 1OO amp breaker wires into the panel feed and integrate my ground!