Expanding circuit in detached garage

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  #1  
Old 11-23-15, 01:16 PM
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Expanding circuit in detached garage

I have a 1950s detached garage that is currently powered by a single 15 amp circuit, which I'm planning to expand to accommodate a few more things.

Currently, the circuit powers only 4 LED interior lights. I'd like to add two exterior lanterns, a receptacle for a garage door opener and a receptacle for a refrigerator.

Below are photos of the current configuration, and the planned expansion. I plan to do this in phases, first expanding the second box to a deep 3 gang and tackling the wiring for the opener receptacle. I plan to protect the two added receptacles using the first (existing GFCI in the run).

I've been told, by latest US codes, I need a "disconnect" since this is a separate structure. I could just install a simple light switch in the first grey box to meet that requirement, correct? (BTW, what is up with the supply wire in that first box - twisted ground wire?)

I realize on only a 15 amp circuit, I might run the risk of tripping with the added appliances; the opener I have pulls 4.5 amps and I'm guessing the fridge (pretty old) could draw 5-7 amps, at least when kicking on. If that becomes common, I'll just remove the fridge.

Also, I'm thinking of using 12/2 for everything in case I ever switch this over to a 20 amp circuit.

Do you guys see anything in these diagrams for concern? How many codes am I violating? :NO NO NO:

Edit: Sporry about the last "Attached" photo at the bottom...old diagram. Ignore please.

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Last edited by DefendersFinish; 11-23-15 at 02:32 PM.
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  #2  
Old 11-23-15, 01:39 PM
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The key problem may be how power is supplied to the garage and if that supply contains a reliable ground. I can't tell which is the supply in your picture but nothing I see is suitable for direct burial. If the garage is not supplied with a ground then nothing can be added because anything added must meet current code which requires grounds.
 
  #3  
Old 11-23-15, 01:56 PM
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I've seen way to many garages wired just like yours.
Other then being able to run a few lights it's way under powered.
Any garage I've built I've installed a minimum of a 60 amp 220 volt sub panel inside the garage.
All outlets need to be 20 amp. 12-2 wire and GFI protected.
Lights should be 15 amp. 14-2 wire.
With 60 amp. you could run a 240 or 120 volt A/C, large table saw, all the tools you want to at the same time and still have enough power.
Not have to deal with tripping breakers and over heated wiring.
 
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Old 11-23-15, 01:58 PM
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It looks to me that you have Part 1 consisting of adding receptacles, switches, etc. within the garage and Part 2 consisting of upgrading the feed from the main house to the garage.

Can you add all the new stuff as Part 1 as a completely separate network with the outlet boxes in slightly different locations so the old stuff remains undisturbed?

Part 1, being completely within the garage, would use ordinary Romex or similar standard indoor wiring provided none emerges from the wall before entering a surface mounted box for an exterior light.

Prior to Part 2 you would not have any direct connection from the new stuff to the old stuff. You would install a box with a male receptacle close to where the future Part 2 would hook in. Use an ordinary extension cord to connect the new stuff (including garage door opener) via the male receptacle to an existing (female) receptacle among the old stuff.

Direct burial cable for Part 2 would include the "UF" style. This needs a 24 inch trench. After Part 2 is done, the male receptacle heading up Part 1 would be removed just before tying Part 1 to its new power source.

The old feed must be decommissioned immediately after Part 2 is hooked in.

I was going to suggest 8 gauge for Part 2 allowing 40 amps at 240 volts, but someone else suggested 6 gauge for 60 amps.
 

Last edited by AllanJ; 11-23-15 at 02:32 PM.
  #5  
Old 11-23-15, 02:39 PM
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Your plan sounds ok to meet code minimum as long as you can verify that the existing circuit is actually grounded properly with a three wire feed (black, white & bare/green wires). Verify that is actually a ground wire and that it is continuous back to the main panel on the other side. With a 1950 install date it is highly suspect of being ungrounded in which case it is not legal to extend the circuit in any way.
 
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Old 11-23-15, 02:40 PM
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Thanks for the input so far, guys - I really appreciate the wealth of info.

To try and answer some questions...

ray2047, in the top diagram, the photo shows the supply line coming from the bottom of the box (black sheathing). I've been told by a few others that the original configuration was most likely two hots and a concentric neutral, which was probably reconfigured to use one of the hots as a neutral, and the old bare neutral as a ground. I presumed, in that case, that the system is sufficiently grounded.

I hear your concerns about this being underpowered, or a phased project. I would love to add more power to this structure some day, but that's a little further off.

Ideally, I was hoping to at least find a way to power a garage door opener before the winter sets in up here in the north east. With a 3 month old, my Mrs. would love a bit of convenience when the weather turns harsh.

So, as I consider rethinking this a bit, let me ask you guys this: if I were to ask about adding only one receptacle for the just the opener, would you still have the same concerns?
 
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Old 11-23-15, 02:50 PM
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he original configuration was most likely two hots and a concentric neutral, which was probably reconfigured to use one of the hots as a neutral, and the old bare neutral as a ground.
If that means SE cable then it means step one is a new feed. SE cable isn't intended for direct burial. In cable #6 or smaller a neutral must be factory white (or gray). A red or black or other "hot" color can't be redesignated.
 
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Old 11-23-15, 02:53 PM
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Ah, good info, Ray.

Sounds like this may be heading from do it yourself to do it with a pro.
 
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Old 11-23-15, 03:05 PM
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Hmm, this one falls into a grey area with regard to what you can or can't do since you can't really verify what type of cable you have. The fact you have three conductors is good. It looks rather small to be service entrance cable, but this could have been installed any time over a span of about 40 years so who knows what product they used at the time. Is it copper or aluminum?

What I would probably do in this case to make sure one of the conductors (the same conductor) is marked with white tape on both ends to ensure the neutral is identified. I would also make sure the bare conductor is grounded on the panel side. I would also replace the first box coming into the garage with a $7 nonfused air conditioner disconnect box which will satisfy both the disconnect switch requirement and provide an effective method of splicing between the unknown conductors and the new wiring.

It would also be a good idea to replace the 15A breaker feeding this circuit with a GFCI breaker. It's about $45 but will guarantee protection on the unknown section of the cable and on all of the outlets in the garage.
 
  #10  
Old 11-23-15, 03:39 PM
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Thanks for the suggestions. I like both ideas of the disconnect and the GFCI breaker and would be comfortable swapping in those components.

I'll do a bit more research at the main panel to see if I can determine whether the bare conductor is grounded properly. I took the photo a few months ago so I don't remember if one of the original hots is marked as neutral - I don't believe it is (although it is pigtailed to the neutral of the 14-3 heading to the receptacles and lights).

I'm not knowledgable enough to know if this is or isn't SE cable. Like you mentioned, I'm not clear when exactly electric service was initially wired for this garage.
 
  #11  
Old 11-29-15, 07:46 PM
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Finally was able to take a look in the main box today. None of these old hot conductors are marked with white tape to signify the use as a neutral, but there are some white pigtailed wires. It seems easily enough to discern what's going on... Please, correct any of these assumptions if I'm incorrect:

I believe the garage circuit in question to be sufficiently grounded. As you can see from the photo, the bare, coiled conductor (which was the presumed ground) goes into the blue wire nut and traces back to the neutral bus bar.

Another conductor comes out of the sheathing before the breaker,then into the yellow wire nut, and finally traces back to the neutral bus bar as well.

Finally, the last conductor leads all the way to the breaker.

I believe this panel was wired right before we bought the house and I'm guessing the contractor who did so ignored the two ground bars on the sides and instead used the neutral bars as grounds (hence the huge jumper at the top).

So, I'm assuming the blue wire nut pig-tailing the bare wire is indeed acting as a ground. The yellow wire nut pig-tails the neutral. The last conductor is obviously the hot.

-----

If these assumptions are correct, I have a sufficiently grounded circuit feeding my garage, right? Yes, probably under powered in the long run, but I could conceivably branch off a garage door opener receptacle as planned..?

Again, thanks for the help!



 
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  #12  
Old 12-23-15, 09:38 AM
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Just wanted to thank everyone who added insight to this thread.

I replaced the very old junction box on the supply line with a non fused AC disconnect - a big improvement to keep things safe and tidy - and began routing some AC planning for the next steps of this project.

For now, I've successfully ran a receptacle up for the opener and installed the opener. No tripping with the fridge, everything working as planned.

I will most likely move the fridge into the basement on a new circuit in the future, and continue to refine the mess that was this branch circuit as I plan for the exterior lights.

Thanks again.
 
  #13  
Old 12-23-15, 11:19 AM
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Thanks for letting us know the outcome.
 
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