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Discussion Starter · #1 ·
Hi all! New to the forum. Im starting a large project. Having a garage built 200' from my houses main breaker. I will use 4 AWG Cu XHHW in undergroung 1" schedule 40 conduit 24" deep. I will run 4 conductors but only will be using 3 for now (ground, hot, neutral) with an extra for expansion if ever desired. I have a roll of 1000' brown Cu XHHW I will be using.

I have 2 main questions.

1. I want to stop about halfway through the run to supply an outdoor outlet box to what Im calling our fruit garden. Will be mounted off the ground on a fence post. A: is this allowable or will this affect the run to the garage, and B: this is a lot thicker wire than 12 or 14 AWG I usually do in the house, what kind of connectors do we recommend inside the junction box? (large wingnuts, lugs etc)

2. Once in the garage do I need a sub panel or disconnect installed before supplying the lighting and outlets? The garage building company hinted at not needed one but im suspicious.

I plan on at most maybe using a 20A tool in the garage. most likely never more than 15A but just to be safe. and in the gardens it will mostly be used for decorative LED lighting and the occasional light power tool.

 

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Discussion Starter · #2 ·
wont let me upload my sketch of the plan
So run from the house to garage is 190' with the junction box planned to be at 90'.
Then a run from the garage to a garden another 90' away.(will do this at some later date next year probably with 6 AWG wire.
 

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A "Handy Husband"
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First, while 4 #4 XHHW will fit in 1" PVC it is barely compliant and will be a very tough pull. Without a sub panel in the garage the max you will be able to supply the garage is a 20 amp breaker in the house. General purpose lighting and receptacle circuits can not exceed 20 amps.

I recommend you upsize the conduit to a least 1.5" and 2" is better. Install a subpanel in the garage with a main breaker. Install an inground pull box at the fruit garden and pull in 3 #12 THWN coductors in the same conduit either from the house or from the garage (whichever is shortest)
 
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Discussion Starter · #4 ·
OK thanks. I can upsize the conduit as I haven't bought that yet anyway. but I used the conduit fill calculators on southwires website and it said low chance of jamming. Perhaps I misunderstood what the meant.

I didn't plan on supplying more than 20A to the garage anyway. but still liked the idea of a subpanel for the sake of distributing the garage wiring.

Why do you recommend an underground pull box at the fruit garden instead of me having both runs of pvc come above ground to a junction box?

Thanks again!
 

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A "Handy Husband"
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OK thanks. I can upsize the conduit as I haven't bought that yet anyway. but I used the conduit fill calculators on southwires website and it said low chance of jamming. Perhaps I misunderstood what the meant.

I didn't plan on supplying more than 20A to the garage anyway. but still liked the idea of a subpanel for the sake of distributing the garage wiring.

Why do you recommend an underground pull box at the fruit garden instead of me having both runs of pvc come above ground to a junction box?

Thanks again!
Coming up to a junction box is fine, it will shorten the pull into 2 runs.

Sent from my Moto E (4) Plus using Tapatalk
 

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Is the conduit galvanized steel? Most likely. If so you may want to consider schedule 80 PVC so it doesn't rust over time. Also if you live in a cold zone 24" may not be deep enough due to ground movement between seasons.
Just something to consider. :wink2:
 

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Master Electrician
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Expansion joints coming out of the ground would be required where I am located... I am pretty sure it would be required in the NEC also.

You only want to dig the ground up once, so don't be afraid to put in bigger conduits and a spare or two... Digging costs more than conduit does...

Cheers
John
 

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That #4 Cu is worth 78 cents a foot or $780 the spool.

Given your requirements, the wire you want for the garage is #4 Al at 26 cents a foot, which will give you *very* acceptable voltage drop, *even in Canada*. Normally I'll chintz out on wire and go 20 cents/foot #6 Al, but going to #4 removes the need to have 3 different colors of wire. So you can get it all done with one spool, and don't have to buy by-the-foot.

"But what are you talking about Harper? **I already own** the copper wire!" Yeah, sell it for darn good money. With the savings, buy the Al wire, and the copper for the garden branches, and most of the conduit lol.

"But aluminum bad!" Not for feeder of this size. It's just the right stuff.

#4 Cu is an awkward size anyway, too big for 60A too small for 100A.

On the garden outlets, absolutely not. You do not have the feeder "make a stop-off" to serve a receptacle. Feeder cannot feed receptacles. It *could* serve a subpanel there, but I don't think you want a subpanel in your garden :) Simply throw a 1/2" PVC conduit in the trench, with three #12 Cu's (12 cents/foot) in the pipe (black white green) and you're done there. That can breaker for 20A, except in Canada you'll need a 15A nanny breaker to keep you from having, OMG, 3.7% voltage drop (like, literally, who cares?)

Don't even bother having the #12 and #4 share the pipe, because you can't just have an underground "Tee": you need 2 stub-ends to surface the box, an outdoor splice box, outdoor splices, etc. etc. And if you ever re-landscape and want to get rid of that box, you can't without replacing all the cable. Not worth it.

Once you get to the barn, you'll need to splice the #4 wire to get down to a size that will go on a receptacle. Those splices are ex-pen-sive and may not allow you to do it one step. But hey, here's one that provides 4 appropriate splices in one box, plus some other stuff you'll find useful. That was easy!
 

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Is the conduit galvanized steel? Most likely. If so you may want to consider schedule 80 PVC so it doesn't rust over time. Also if you live in a cold zone 24" may not be deep enough due to ground movement between seasons.
Just something to consider.
Cold zones do not affect burial depth for electric.
 
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Cold zones do not affect burial depth for electric.
The ground movement does during freezing and thawing of the ground, the moving of pipes and or PVC ect. One needs to consider the flexability of conduit vs PVC for water leakage especially with electrical lines. PVC is much more forgiving from flexing due to the seasonal thawing of the ground. Conduit unions are much more susceptible to leakage due to this factor. The last thing I would want is water leaking into conduit buried under ground.
 

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Expansion joints are used to compensate for frost heave, not increased burial depth.

Condensation will form in the conduit. That is why the conductors need to be wet rated.
 

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A "Handy Husband"
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Poster you may want to reconsider the pull box when you see the cost and size of the box. Better to run a second small conduit to feed the garden.

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Discussion Starter · #13 ·
Thanks for the replies.
So would It likely be easier to run a smaller conduit backtracking to the garden to provide the outlet? I'm also running a cat6a cable out to the garage in a seperate 1 inch conduit. So for a stretch I would have 3 conduits. Do they have to lay side by side with x amount of space between them?

I'm not sure I've seen these expansion joints were talking about.

Also yes I'm planning on using schedule 40 pvc conduit
 

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