Detached garage sub panel

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Old 04-17-16, 10:56 AM
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Detached garage sub panel

I am about to start my detached garage sub panel. The garage currently is fed through conduit and has (2) 110v breakers in the main. Which to my understanding isn't code to begin with.

My question is can I have my sub and leave the existing wiring in place. So my lights and 110v sockets would be ran from the house and only my heavy machinery from the garage sub panel? My thoughts are probably not but that's why I'm asking. Either way I would eventually run everything through the sub panel. Leaving the existing wiring intact just saves me around 100$ and would allow me to do the rest as I go.
 
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Old 04-17-16, 11:14 AM
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The garage currently is fed through conduit and has (2) 110v breakers in the main.
By two 110 volt (really 120 volt) breakers do you mean two single pole breakers, or two breakers that are tied together with a handle tie?
My question is can I have my sub and leave the existing wiring in place. So my lights and 110v sockets would be ran from the house and only my heavy machinery from the garage sub panel?
No. A building may only have one feed with the exception of three way lighting between buildings.

Leaving the existing wiring intact just saves me around 100$
What size are the existing wires?
 
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Old 04-17-16, 11:21 AM
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It is ancient wiring with some type of cloth wrapping but I would guess that it is 12-3. Yes 2 different breakers. This is not counting one 3 way switch from the house for the exterior garage lights.

So it sounds like I should just by 100' of 12-3 and redo all the wiring from the rip.
 
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Old 04-17-16, 12:52 PM
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So it sounds like I should just by 100' of 12-3 and redo all the wiring from the rip.
12-3 (White, black, red, ground) would be cable. Best practice is to use individual conductors such as THWN in conduit. However if the conduit is EMT it probably isn't reusable. EMT rusts out quickly.
 
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Old 04-17-16, 01:17 PM
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If you are redoing the feeder anyway, and planing to run "heavy machinery" I would recommend running a larger feeder then 12-3. Depending on what you are planing to run I would go with a 30 amp (#10 feeders) or even a 50/60 amp (#6 feeder) for your sub panel.
 
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Old 04-17-16, 02:51 PM
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The new feeder I'm running will be 2-2-2-4 AL MHF and it will be run in new 2" pvc. I was questioning whether it was code to leave the pre existing service and switch everything over to my panel at my own convience or just plan on rewriting it at the same time.

I'll prob just end up doing it all at once because the more I think about it that's what makes sense.
 
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Old 04-17-16, 04:27 PM
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I was questioning whether it was code to leave the pre existing service and switch everything over to my panel at my own convience or just plan on rewriting it at the same time.
It was already mentioned that you are only allowed one power feed, but I wouldn't worry about it taking a few extra days to disconnect the existing feed and changing existing wiring over to the new subpanel.
 
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Old 04-17-16, 04:48 PM
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Not not an electrician, but as a contractor in the past had to deal with this all the time and became one of my biggest pet peeves.
There's just no way you can run to much power to a garage, but it sure is possible to under power it.
Time and time again customers would tell me to save money they only need one outlet to meet code and a few lights and only wanted a couple of lights.
Later on they decide, or the new owner says now I need to add A mini split, window A/C, got a deal on a 240 volt table saw or compressor, ECT.
There's just no way to do it if all they have is a single 12-2 line.
Now they have to pay twice to get it done right.
 
 

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