Is an underground junction box possible here???

[Techie1961]

I am building my shop and electrical is one of the next things on my todo list. Money is tight so I am thinking about something. On our property, we have a main house as well as a guest house (which we used to rent out) at the back of the property. There is one meter and two feeds at the main house with 200 amps each. The 200 amp that goes to the back house is run with 3/0 copper in 2" PVC conduit and runs right past where I need power for my shop. The house at the back doesn't need 200 amps but the previous owner liked overkill.

In the image, the century barn that I am converting to a shop is in the middle. The right side shows the main house and the lower left side is the guest house. The upper left side is an open steel pole barn with a 60 amp panel. The line is approximately where I believe the conduit runs.

Is it possible to have an electrician cut in near the new shop and put in an underground junction box so I can pull 100 amps from that run? It's the weekend so I can't talk to one and I want to figure out how I am going to do this.

 

[theoldwizard1]

They make special under ground splice kits. Special splice block and then 2 layers of double wall heat shrink. Not cheap, but no J-box required.

I had to use one at my son's house where we found out that the previous owner had buried the 10/3 UF going to the garage 6" below grade and the new grade (so that rain water would not run into the garage) need to be lowered 6".

 

[wyliesdiesels]

It would probably qualify as an outside feeder tap under 240.21(b)(5)

But u have specific requirements:

*First, u would need either a disconnect or a panel with a main breaker on the outside of the shop and the wire needs to be rated for the ampacity of the OCPD.

*The conductors need to remain outside except where they enter structure

*The wire needs to be protected from physical damage (ie conduit).

Heres a short article u can reference:

http://m.ecmweb.com/code-basics/understanding-rules-feeder-taps

U mentioned an existing panel and feed. U would most likely need new wire and the existing one would have to be abandoned.

Whats wrong with the existing feed?

But before u consider this, is the existing feed 3-wire or 4-wire. If 3-wire, then its a no go because 3-wire feeders are no longer allowed as of 2008 NEC.

Some other things u need to consider include the load of the back house and the load u will have in the shop.

Also, what is the length of the wire?

If the total future load is a good amount, u may have voltage drop issues!

 

[zmaxmotorsports]

If you were to bring the existing pvc pipe up into a pull box with a couple of 90's youll end up being short on wire to feed the guest house.
Depending on how far the shop is from that point you might be able to use the shorter wire to feed to the shop.

 

[Techie1961]

Thanks for the quick responses. I'm in Canada so not sure if the code is different here (probably is). This is a shot of the disconnect that goes to the elbow on the main house's wall and then underground to the back. Not sure if this is 3 or 4 wire. Does the ground count? I'm not sure why the photo came out sideways but the conduit is at the top.

 

[alfredeneuman]

There's no such thing as a true underground junction box that you can bury.

The cover must be accessible and located at or above the grade.

Since you have conductors in conduit it wouldn't make any sense to use the underground splice kits without a box. The conductors themselves aren't rated for direct burial.

 

[wyliesdiesels]

Whoops!

I totally didnt check your location.

Im an electrician in the US so some or all of what I said may not apply.

I have read that the CEC and NEC are similar in some regards however....

U need people from Canada to comment...

 

[zmaxmotorsports]

Wjhen I say pull box Im thinking of something like this but smaller,depending on the use.

 

[sberry]

No, I am amazed how fast a how to question can stray from rudimentary design basics. But a picture would help. After the 200 disconnect going to guest it likely wouldn't be a problem to add a circuit to the new building. Whoops a pic is here, I read this again. One of the sparks can tell how to tap it after the fact.

 

[Techie1961]

So it looks like a maybe. I got a text from my electrician and he is going to drop in this week to have a look. I didn't describe the needs yet but will once he drops in. Simpler that way. Thanks to all that responded and I am definitely interested in more input if you can. It's nice to have a bit of a clue once he shows up.

 

[sberry]

Basically you need a set of lugs following the fuses to add another set of wires for the new install. You may not need full 200 to the shop but the wire will need to be laege enough to be connected to 200A disconnect.

 

[Slowgsr]

I'm a licensed contractor from your area and the simple answer is - no.

You would need an accessible junction point, with access from grade level, and it's doubtful you would have slack in those feeders required to splice them. Splicing 2 wires is one thing but x3 3/0 cu is another, and you would have to maintain wire size or de-rate the whole run and fuse to match the size of the feeders you run to your barn. It's just going to be headaches, moisture always finds it way in anything below grade.

The best solution is to trench from guest house and feed the barn from that 200a system. Or the house, whichever is close. Do it right, do it once.

Do you plan on taking out your own permit? Edit - I see your hiring one or having one come out, if they do any type on underground splice insist on a permit. Lots of Mickey mouse stuff happens these days when guys don't need to pull a meter I'm a residential setting

 

[Techie1961]

I'm a licensed contractor from your area and the simple answer is - no.

You would need an accessible junction point, with access from grade level, and it's doubtful you would have slack in those feeders required to splice them. Splicing 2 wires is one thing but x3 3/0 cu is another, and you would have to maintain wire size or de-rate the whole run and fuse to match the size of the feeders you run to your barn. It's just going to be headaches, moisture always finds it way in anything below grade.

The best solution is to trench from guest house and feed the barn from that 200a system. Or the house, whichever is close. Do it right, do it once.

Do you plan on taking out your own permit? Edit - I see your hiring one or having one come out, if they do any type on underground splice insist on a permit. Lots of Mickey mouse stuff happens these days when guys don't need to pull a meter I'm a residential setting

That's too bad. It's a shame with the power so close but yet so far away. He will handle the permit.

 

[wyliesdiesels]

I'm a licensed contractor from your area and the simple answer is - no.

You would need an accessible junction point, with access from grade level, and it's doubtful you would have slack in those feeders required to splice them. Splicing 2 wires is one thing but x3 3/0 cu is another, and you would have to maintain wire size or de-rate the whole run and fuse to match the size of the feeders you run to your barn. It's just going to be headaches, moisture always finds it way in anything below grade.

The best solution is to trench from guest house and feed the barn from that 200a system. Or the house, whichever is close. Do it right, do it once.

Do you plan on taking out your own permit? Edit - I see your hiring one or having one come out, if they do any type on underground splice insist on a permit. Lots of Mickey mouse stuff happens these days when guys don't need to pull a meter I'm a residential setting

Does Canadian code not allow unfused taps?

 

[pentavolvo]

Go past the garage dig it il and pull it back far enough to get into garage with 200 amp sub, then a new line all the way to guest house from garage for 100amp

 

[Slowgsr]

Does Canadian code not allow unfused taps?

Only the utility companies get to do that up here. Consumers unfortunately not.

The above suggestion to trench and pull it back then into the barn would work, but i see the risk of damaging the conductors and i would make it at the risk of the home owner if this was chosen.

 

[tfi racing]

Go past the garage dig it il and pull it back far enough to get into garage with 200 amp sub, then a new line all the way to guest house from garage for 100amp

Not a bad idea,but a lot of work and a bit of a risk.I agree with slowgsr,trench and new feed from house would be the easiest and best way.

 

[Techie1961]

The electrician let me down this week but may be out tomorrow morning to have a look. I kind of like Pentavolvo's idea if truth be told. We'll see what he has to say.