A/C Disconnect

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  #1  
Old 08-14-12, 09:01 AM
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A/C Disconnect

I need to run new service to my detached garage. Plan is to run 60a service. I'm good with the panel space, wire size, wire type, and conduit. my question is can i use an Disconnect that is typically used for an A/C condenser to act as a junction point because at the moment i don't have the time to to do the full job.

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Old 08-14-12, 09:40 AM
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I don't really understand. Normally you would use the main breaker in a subpanel as your disconnect unless the subpanel only had spaces for six or less breakers then you don't need a disconnect. The branch circuit breakers serve as the disconnect. Why can't you just use a junction box and where is this place located, house, garage, other?

I'm good with the panel space, wire size, wire type
But since your here why not give us the details just in case you've missed something. For example older code required three wires only in most cases but modern code requires four wires. We have had posters in the past that thought conduit wasn't considered a wet location or that cable was was best choice in conduit. In other cases buying wire two large for the amps and therefore over spending.
 
  #3  
Old 08-14-12, 09:58 AM
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Just to further Ray's point, here is what I had in my garage at my old house. It was a detached garage with 60A service fed from the house.
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My sub pannel did not have a main, so the power came into the garage into a main breaker, then into the pannel.

If I was to do it again, I might have relocated the main closer to the man door. This way, if something went bad, I could hit the main on the way out the door (like having fire extingishers at the exits).

Otherwise, it worked great.
 
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Old 08-14-12, 10:06 AM
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i knew it wouldn't be that simple i was in a rush.. so, here's my situation... i'm finishing my basement and i'm about to drywall. I need to run new service to the detached garage so i can install a lift. but, i don't have time to dig the trench, move all the junk in the garage, etc. so, what i thought i'd do is mount an A/C disconnect something like this 60 Amp 240-Volt Non-Fuse Metallic AC Disconnect-TFN60RCP at The Home Depot
and run the service to it so that when i'm ready i can finish the job to the garage.

All of the disconnects say for A/C.. why? is there any technical or code reason why i can't use it as a junction box?

thanks
 
  #5  
Old 08-14-12, 10:17 AM
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Best bet, run the wires to the in house pannel, but do not connect it to the pannel. Leave the rest coiled up where it will exit the house. When time permits, run the cable to the garage and make your connections.
The in house pannel should be a double breaker (220V) 60A if that is what you are going for.
The main disconnect should be in the garage (probably code as well). This way you can access it in the garage if you need to.

As I mentioned in my post, I would put my main near the man door. I don't think this is required by any code, but it does add another level of safety when things go bad.
 
  #6  
Old 08-14-12, 10:36 AM
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absolutely on the breaker and i will ultimately use a 100 am subpanel...

That was my original plan to leave a coil. but, i'll have 50+ ft of coiled wire. really not practical with #6 wire.. so, i figured why not use the disconnect like the one on my A/C unit... still not sure what's technically wrong with that???
 
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Old 08-14-12, 11:18 AM
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Nothing technically wrong with the disconnect. It is just not needed. Till you run it you can just leave it disconnected at the main panel (wires capped). And just use a 6x6 junction box instead of a disconnect.

but, i'll have 50+ ft of coiled wire
That's four coils of wire, correct?
 
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Old 08-14-12, 11:28 AM
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I too second the idea of running the conductors into an accessible junction box for future splicing to the underground run to the garage. IMO an A/C disconnect does not give you as much room and you will still need a disconnect at the garage.
 
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Old 08-14-12, 12:56 PM
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Or plan "B" run conduit from the panel to the junction box and no wire till ready then just use the junction box as a pull box. No wires needed till your ready and eliminates one splice.Doing it this way you could probably use a 4x4 box.
 
  #10  
Old 08-14-12, 01:53 PM
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was going to do 3 wires and an isolated ground by the garage. but, can go either way.

so, in the 6x6 junction box, how would i tie the conductors together for the leg to the garage, wire nuts? that just doesn't seem robust enough to me...

the disconnects are cheap and make really easy work of it.

the conductors will be run in conduit, not sure what size i have. i think 1" sch 80 PVC. so, i guess, i could ruf the conduit and leave a pull rope...
 
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Old 08-14-12, 02:40 PM
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was going to do 3 wires and an isolated ground by the garage. but, can go either way.
Modern code (NEC) requires two hots, one neutral and one equipment ground wire (EGC). The EGC on 60 amp can be #10 green or bare the other three #6 THWN (neutral white, hot colors optional except for restricted colors but usually two blacks or a black and red are used. In addition to the EGC from the panel you will need an eight foot ground rod at the subpanel connected with a #6 GEC (grounding electrode conductor) to the ground bar. Panels do not normally include a ground bar so you will have to buy and install one. The ground bar is bonded but the neutral bar is isolated.

so, in the 6x6 junction box, how would i tie the conductors together for the leg to the garage, wire nuts?
Split bolts covered with rubber tape and friction tape (or PVC electric tape) or Polaris style insulated connectors.

You only need schedule 40 conduit. 1" is good for up to seven #6. Note if you are going to use NM-b between the main panel and the junction box you are technically limited to 55 amps*. If you use conduit and THWN you can go to 60 amps.

*Normally an inspector will allow using an up sized 60 amp breaker if no 55 amp available for your panel but just making you aware.
 
  #12  
Old 08-14-12, 02:43 PM
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awesome.. thanks for all the input
 
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Old 08-14-12, 02:50 PM
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Added some as you were posting.
 
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Old 08-14-12, 09:49 PM
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You can get wire nuts that are good for 2 #6s. Way cheaper than a Polaris and easier than a split bolt.
 
  #15  
Old 08-22-12, 05:30 AM
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so looked in the garage and all i have is 3/4" conduit. can that handle the 4 conductors for the 60a service?
 
  #16  
Old 08-22-12, 06:17 AM
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What type of conduit?

................................
 
  #17  
Old 08-22-12, 07:26 AM
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schedule 40 PVC......................
 
  #18  
Old 08-22-12, 08:16 AM
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Yes. Up to 4 #6 THWN wires are allowed in 3/4" schedule 40 PVC. Dropping to #10 for the EGC will make pulling easier.

It's going to be a bit tight on the pull. I would make the head really smooth, use plenty of lube at the start, and ensure that the conductors stay aligned as they are pulled in.
 
  #19  
Old 08-22-12, 09:03 AM
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that was what my research told me. good to get confirmation... I figure it'll be tight. PVC is cheap, but i have more than enough of the 3/4 to cover the job... thanks for the info...
 
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