Sub Panel in Shed and Aluminum Feed


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Old 05-07-15, 10:04 AM
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Sub Panel in Shed and Aluminum Feed

Hello,

I have a cottage which I am going to upgrade the main fuse box to a Sq D QO breaker panel, 100 Amp to basically keep my insurance company happy. Last fall I built a 20' x 30' shed......now I plan on running power to the shed. The shed is about 100' away from the cottage with another 40' to the breaker panel underneath the cottage and through the crawl space for a total around 150' or so feet.

I was looking at 6-3 w/g uf-b copper, which isn't cheap, with 55-60 amp protection. I have a 6 slot SqD Homeline sub panel in the shed. I plan on direct burial 24" deep.

I found Aluminum quadruplex 4-4-4-4 for about a third of the cost of copper and was considering using it as feed between the two buildings, buying enough Al to bury and then end inside the crawl space, across the floor joists with 6-3 copper to the main panel in the cottage.
After reading up on aluminum wire and its history, it appears it would be suitable for this type use. My main concern is splicing the two. I was wondering if there is an enclosure available with strips similar to power distribution blocks like in a panel where I could terminate the #4 aluminum on one side and #6 copper on the other, both coated w/antioxidation gel plus torqued to the correct values.
I think it would be easier to run copper from under the cottage to the main panel than a bundle of aluminum all the way.

My load in the shed would be some fluorescent lighting, 100 ac outlets for power tools, a radial arm saw and a small 120 or 240 compressor. Nothing real heavy.

A friend who does light electrical work with a local inspector will be helping, plus I will get it bought off. My insurance will require an inspection.

I haven't made my mind up which way to go yet, just looking for opinions.

What do you guys think?

I found a place called wire and cable to go....online.
 
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Old 05-07-15, 10:21 AM
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I think your plan is fine. 6/3 NM-b for the crawl space to a junction box, then splice to your #4 aluminum. A good splice to use is like this:
[ATTACH=CONFIG]50211[/ATTACH]

No other insulation needed and they are rated for aluminum and copper. They also make ones where both wires enter the same side.

#8 is fine for your ground wire at 60 amps.
 
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Old 05-07-15, 10:41 AM
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Do you know exactly what kind of wire the #4 aluminum is? If it's the right type it may be overall cheaper to run some conduit through the cottage and keep the aluminum for the whole run rather than buy the expensive connectors and the 50' of copper. Just a thought. Otherwise the plan is sound.
 
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Old 05-07-15, 04:58 PM
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Thank you for the replies.

The aluminum is 1350 grade 7 strand according to 'wire and cable to go'.

I actually have another option which would be all the way from the shed to the cottage around the outside of the cottage but it has several 'problems'. A 40 foot Hemlock which I was concerned with disturbing the roots, a piled field stone wall that needs gone through in 2-3 spots and tight access due to the wall and tree. It would be easier and cheaper just feeding the subpanel and the 60A breaker in the main with one wire bundle.

I'm going to see what my backhoe guy thinks.

Thanks for your advice.
 
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Old 05-07-15, 05:40 PM
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IBpooks was referring to the type of wire (We are assuming direct burial), USE, XHHW, URD etc. Some types are OK to use outside direct burial while not approved inside a building. If you could run conduit under the cabin to the panel you might be able to just run the aluminum wire the entire way.
 
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Old 05-07-15, 05:54 PM
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Old 05-08-15, 06:16 AM
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Yeah it looks to me like that cable has to remain outside the house due to the insulation type. It probably shouldn't even go into the main panel (assuming it's inside). The original plan sounds good with a splice box on the back wall of the house to transition between the 6-3 copper NM and the underground quad aluminum.
 
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Old 05-12-15, 07:34 AM
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Can you elaborate on why it couldn't go into the main panel mounted inside but on an outside wall and fed through 1 1/4 conduit inside the wall?
The panel is set up for #4 size wire.
 
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Old 05-12-15, 07:49 AM
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The URD (underground residential distribution) cable types do not have the smoke or flame retardant ratings that are required for use in occupied structures. An outdoor panel should have all of the penetrations into the home sealed with duct sealant putty to prevent the spread of gases between the indoor and outdoor spaces. Ultimately it's up to your local inspector whether a short piece is allowed into the home or not, but by the strict letter of the building codes URD shouldn't enter the building envelope.
 
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Old 05-12-15, 07:51 AM
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Some cable insulation can not be used inside because of the fumes it releases in a fire.

Darn, Ben types faster.
 
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Old 05-12-15, 08:09 AM
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Thanks to both of you. I was going to contact the inspector regardless.
If he says no, are there some type enclosures I could mount outside that have power terminals much like inside a breaker panel that I could splice to or would one of those Morris splices like was shown earlier be ok inside a weather proof box? And could that Morris splice be folded back into the box much like twist on wire nuts?

Also, does the same go for up in my shed?
 
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Old 05-13-15, 09:38 AM
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Been doing some reading, I read up on the insulation on UF type cable, and see what you were saying....
How long do you guys study this stuff for before you get tested for a license? I hold a aviation maintenance certification and studied Fed regs for two years and took 3 different exams to get licensed. It seems there's way more in the electrical code than what I dealt with for my license, but a lot probably becomes less frightening as you learn....

Anyway, I opened the wall in the cottage to see what was done and how the wiring was run. I can put the new panel to the left of the old fuse box and all the old circuits can be transferred to the new panel without any splicing except maybe one, which was spliced and has about 50 pound of electrical tape on it. I'm going to see where it goes in the attic and try and replace the wire from wherever it terminates.

The 100A fuse box only used 3 circuits, as the fourth was a 110v water heater which I replaced with a 240v and ran it off water heater pull out. Also I have a 240v well pump run to a separate enclosure off the water heater lugs. They put the well pump in with that twisted wire suitable for burial from the pressure switch at the well to the breaker box in the house w/o conduit. It runs through the floor inside the wall......does this twisted pump wire have to be in conduit inside the wall where it comes into the cottage or is it ok feeding into the panel like they did w/o conduit?

My grand plan is changing over the cottage panel first, (Monday)then putting the sub panel in the shed, then getting a guy to dig me a trench and put in that quadraplex feeder plus grounds. I thought you could put the sub in and get the work bought off but I found some minimum wiring requirements while reading, which I suppose I'll have to do before a final inspection, right? I mean, you wouldn't buy off the main panel, feeder and sub off only?.....I have to have minimum lighting and outlets also before a buy off?

I really appreciate your help. I'm just trying to get all my ducks in a row before contacting this inspector my friend uses. I mentioned contacting this inspector in the previous post, I was referring to like you guys usually mention after giving advice,'check with your local inspector'......I hope you didn't take that as a snub.

Thanks again for all your help.
 
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Old 05-13-15, 11:19 AM
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For the connection between the two cables use a 6x6 PVC box. Example: Cantex 6in x 6in x 4in PVC Molded Junction Box (5133710U) - PVC Boxes - Ace Hardware Connect the wires with split bolt connectors intended for aluminum to copper.
 
 

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