I have a question and need some electrician type expertise. I have 50 amp 220v single phase service in my detached garage at this time. It currently only has a few 110v outlets and fluorescent lights running from the electric box, which is a separate breaker box in the garage. My new welder states it needs 50 amp 220v. I would also like to get a bigger air compressor that would run off 220v. Here is my question, can I put a BIGGER breaker than the 50 amp one that is currently feeding the garage? in other words, could I put a 60 or 70 amp breaker in my main house box instead of the 50 amp current breaker to feed the garage without having to pull new wiring? If I can run a bigger breaker, then I would not be up against the limit as i would be with the welder. I understand the welder will not pull full load of 50 amps, as it hardly ever would be a at max load. But if I were to add the compressor or just running too many lights and 110v tools, I could start tripping the 50 amp feeding the garage? Thanks for any advice or help, I am not sure if I could pull new larger wires through the conduit feeding the detached garage. Is there a rule what size wire is needed for a given amp breaker? Terry
Yeah, that 50amp would pop everytime your welder arced. Slap in a 100 or a couple of them, but make sure your wiring isn't too shabby. If it looks pretty bad, spend a few dollars to beef it up a bit. I know you shouldn't, but I have 2 welders, a big ass 80gal compressor, all running on the same 240 circuit. I never use all of them at the same time so I've never had a problem wiring it that way. But my breaker for that circuit is 100amp.
I'm not an electrician, I'm an EE, but... You ABSOLUTELY need to find out if your wiring is capable of passing 70 amps instead of the 50. If your wiring is only capable of 50A, passing 70A through it could cause a pretty bad fire, overcurrent is a MAJOR firestarter... I've started pleteny of fires that way. If you're not sure, pay a electrician just to have a look or a house inspector or something. Even if your wiring LOOKS good, some wire just isn't a sufficient enough gauge to safely pass 70A at 240V (that is a SHITload of power, even just momentarily, over 1.6kW, so you want to be safe). I forget how big you'll need, legally and mathematically, but it will be at least 8 AWG, probably 4, especially if its a long run. Your compressor and anything else with a large electric motor will pull a bigass load of current when it starts up, if it'll trip the breaker it will be then.
Thanks for the link and also the info confirming what I thought. I need to determine what wire size i have and then see if it can handle more than 50 amps. Hopefully I get lucky and have 4 or 2 gage wiring from the house box back to the detached garage and can up the breaker size above 50 amps. Any other advice or help?
Check out electrician.com There are some calculators on there that will tell you what you need to know. If you have any doubts, get an electrician.
you need to make sure you change the breaker feeding the sub-panel in the garage. Make sure that the house panel is big enough to handle the swap. Also you can use bigger wire than you need but read the labels on the equipment USE THE RIGHT Size breakers in the sub panel it WILL burn the breakers. I do A\C work I see Burnt breakers all the time from "friends" doing favors if you can't do it pay a licensed contractor so as not to get screwed if something happens. You can look at the charts and do a load calc. on it to get yer wire size from the house to the sub-panel
Had my detached second garage wired last year and I've got to agree with those who advised hiring an electrician. I'm a decent amateur electrician, but there's a lot I didn't know about wiring a sub-service box. I do know that the main service panel needs the extra capacity and has to have the correct wiring and circuit breaker for the line to the garage sub-panel. And, the specified size wire must be run to the garage panel. (Probably a 2 or 4 for 70 amps). The garage panel inlet circuit breaker needs to be matched to the outlet circuit breaker on the main panel. The national code requires a detached structure with a sub-panel to have it's own grounding rod. According to my paperwork, the max amp draw on my Lincoln is something like 24 amps even though it has a 50 amp plug on the cord. I think most come with 50 amp plugs for standardization.
Have you considered adding in new power to the shop that is separate from your house entirely? If it is less than 100 feet to a power pole most power companys will wire this for free if you provide the meter socket and all required wiring inside. I did this over the winter, I now have 200 amp service to my shop, with all new wiring, a new breaker box, all the stuff. The only hassle I had was I did have to buy a permit and have inspections done and stuff. Power company didn't charge me anything for the new service. This was all fine by me though, should there ever be a fire or any other issue I have nothing to worry about with insurance because it was all inspected and approved. If I had to guess, I would say not including permits and crap my total investment was about $600.00-ish. The power company up here charges me a whopping 9 bucks a month plus usage for having dual meters on my property, so my power bill is hardly squat for the shop because i'm onlu out there evenings and weekends. also, I did the same thing with the gas company, all I had to do was get a signed permit for my furnace install, and the gas company came out and put in a new main and meter to my shop, fee for that is 12 bucks a month plus usage in the winter and 6 bucks in the summer plus usage. They didn't charge me anything to install the new main or meter. Scot
Thanks to all that replied. I will check the wiring size, and the main house feed to ensure they are proper size for the upgraded breaker. Assuming that both can handle it. If not then I will have to consider other options, such as pulling new larger wire to feed the garage. That comment about the actual max load the welder pulls being much less than 50 amps helps me feel better in case i am near the size/amp limits.
LoL kind of wierd I was just a work today...I'm a electrician and anyways yea in a little suburb home they wanted a box and wire for a welder in a room off of the garage. Work shop the wife said and so I wondered if the husband had any cars. but anyways and so we ran the big range cable into the 4 11/16th box. And I talked to my boss and he was saying all that stuff about how they put a 50 amp in and how the owner could throw in a 60 or 70 in after a few months and the wire wouldn't be able to hold it. Or he might of said it will hold it. lol I cant remember, all I do is pull and strip wires
I'm a Journeyman electrician. Been in the business for better than 25 years now. I suggest you bite the bullet and call a licensed electrician in. An inspection and estimate won't cost much if anything. There are many details that need to be done right. You can easily burn your house or kill yourself (or someone else) if things are done wrong. Electrical wiring is NO PLACE to get cheap.
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