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Forum topic by Jake229 posted 04-09-2020 01:27 PM 379 views 0 times favorited 18 replies Add to Favorites Watch
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Jake229

23 posts in 206 days


04-09-2020 01:27 PM

Topic tags/keywords: question

Hello! My new workshop broke ground on Tuesday after much debate and stress of location, detached versus attached, foundation and of course stick built vs post construction. I decided on foundation and slab, 24×32, 10’ walls with posts built onto the foundation. Not the most economical way to build, but due to slopes on the property the most sensible. I am trying to stay one step ahead of the concrete guy and need to be thinking of power to the shop. Going to put a couple of schedule 80 elbows embedded in the walls to pull electric through, along with cat 6 wire for internet and anything else I would ever want. The shop is just under 30’ from the house. With that said, I have a couple of questions for the “sparky’s here. I have 200 amp service in the house. Want to run 100 amps to the shop. Been considering 3-3-3-5 Copper but it isn’t rated for conduit as it is a ser. I want to use a singe cable if possible from indoor panel, 20’ inside residence to the exterior walls, then 30’ to the shop. If at all possible. Am I barking up the wrong tree? Am I destined to converting to individual conductors in a junction box outside the residence in order to do this? Thanks for any assistance you all can provide.

-- Be safe out there


18 replies so far

View ibewjon's profile

ibewjon

1756 posts in 3597 days


#1 posted 04-09-2020 02:07 PM

I would use 1 1/2” conduit, panel to panel, and individual conductors. What is the reason for schedule 80? Local code? I would use conduit all the way. Not that much money. I have not checked prices lately, but pipe and individual conductors probably no more money than a direct burial cable. I hate direct burial, it always fails at the worst time. Middle of a January blizzard? Add a third conduit, maybe a 1” for a light on the shop switched from the house, or other ideas later.

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Heyoka

57 posts in 657 days


#2 posted 04-09-2020 02:11 PM

I believe that the low voltage wire cannot be run in the same conduit as the service wire.

-- Heyoka

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WhyMe

1299 posts in 2365 days


#3 posted 04-09-2020 02:14 PM

SER is not allowed underground in conduit. SER can be placed in conduit only above ground. To get 100A you need either #1Al or #3Cu. My suggestion is to run at a minimum 1.5” PVC conduit panel to panel and use three #1 Al XHHW-2 conductors and one #6 Al XHHW-2 conductor. Aluminum is about a third of the cost of copper and is safe to use. You can use SER Al 1-1-1-3 for the inside run to a junction box and transition to conduit with individual conductors for the run to the shop.

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Robert

3790 posts in 2285 days


#4 posted 04-09-2020 02:14 PM

Pretty much all service cables are aluminum nowadays. You would need a special junction for switching CU from breaker over to AL to shop.

I strongly suggest you have an electrician do at least the panel so you can be sure its up to code. Offer to dig the trench they usually like that a lot.

The rest of the wiring you can do. When I remodelled I went with surface mounted conduit.

IMO the only way to go avoids cutting holes in wallboard, just insulate and go with your walls.

-- Everything is a prototype thats why its one of a kind!!

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WhyMe

1299 posts in 2365 days


#5 posted 04-09-2020 02:23 PM



……… You would need a special junction for switching CU from breaker over to AL to shop.

- Robert

Why in the world would you mix copper and aluminum??? Use one or the other for the feeder.

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Jake229

23 posts in 206 days


#6 posted 04-09-2020 02:23 PM

Thank you! I greatly appreciate the quick replies. They are pouring footings today! Lots to think about for sure. Was originally planning on using an electrician for wiring shop panel, till I got the first quote of over 3000, but he did include the square d QO breaker panel. He offered to reduce the price by 150 if I did the trenching. Schedule 40 would work just fine and separate wires (3) with ground is what I will use. Will go panel to panel with conduit. Will post progress as it moves along. My dad never got his dedicated shop, I am giggling with excitement

-- Be safe out there

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WhyMe

1299 posts in 2365 days


#7 posted 04-09-2020 02:48 PM

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BurlyBob

7700 posts in 3070 days


#8 posted 04-09-2020 03:27 PM

If he doesn’t chime in PM WWBob. He’s the resident electrical expert.

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ibewjon

1756 posts in 3597 days


#9 posted 04-09-2020 03:37 PM

That is correct. Low voltage, cat 5, tv, or other systems must be in separate conduit from 120/240 volt power wiring. You will also need a ground rod at the shop. As for aluminum wire, the larger size required is harder to work with. You need to use anti oxidant paste on connections. Electrical is the life blood of your shop. You are spending thousands of dollars on the shop. It it really worth saving a little by using aluminum wire? And some codes do not allow aluminum wire to enter a building. The reason few projects use aluminum is that it just isn’t worth the savings. And yes, I know all about the new alloys.

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WhyMe

1299 posts in 2365 days


#10 posted 04-09-2020 06:33 PM

Here we go again…. there is nothing wrong with using aluminum wire for a branch feeder to a subpanel. It’s not hard to work with and also anti-oxidant past (Noalox) is no longer required, neither by wire manufacturers nor the NEC. Nothing wrong with using it but it’s just an old requirement that keeps being pushed. I’ve installed many a feeder to detached shops and more times than not it’s been aluminum because of the distance and cost of the wire. Yes there are some places that don’t allow aluminum inside the structure so a check with your local authority is recommended.

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Jake229

23 posts in 206 days


#11 posted 04-09-2020 06:40 PM

Appreciate the info! I can use either aluminum or copper. For me, it’s more about using something that I have used before. I wired a sub panel in an attached shop a few years ago and it worked well. The difference was it was attached. This shop is detached. I do want to use conduit from panel to panel. Just didn’t know if I could use a pre-made cable or if I needed individual wires. What I didn’t want was to have to switch wire types midstream.

-- Be safe out there

View CaptainKlutz's profile

CaptainKlutz

3347 posts in 2298 days


#12 posted 04-09-2020 07:40 PM

+1 Need separate conduit or trench for low voltage and high voltage. Check your local code.

IME – There are huge number of nit-pick code details with sub-panel in detached building .vs. an attached structure. The above discussion on use of Al wire inside/outside and local code difference is just one of many challenges. NEC code has ground rod requirements, but your local soil may force different requirements. Use of conduit .vs. direct burial wire and cost implications is another heavily debated topic.
If you have never done a detached building panel install or new building install before;
highly suggest you hire a professional.

IMHO – $3k to wire a fully wire a detached 24×32 workshop with 100A sub-panel and rack full of 120/240v circuits is not ridiculous, depending on your area? But, You have not shared enough information for fair comparison.
Rural areas are often challenged with limited competition for electrical supplies, and due heavy shipping weights are more expensive? I do think $3K is a little high, but it is easy to quote a couple electricians and see if you can get better price. The challenge with comparing prices is detailed list of requirements.

Be safe, not sorry!

-- If it wasn't for bad luck, I wouldn't have no luck at all, - Albert King - Born Under a Bad Sign released 1967

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WhyMe

1299 posts in 2365 days


#13 posted 04-09-2020 07:48 PM

If you use copper, THHN/THWN is the most common. The XHHW-2 does come in copper but I don’t know how available it is to you. The copper XHHW-2 may be a few pennies more a foot than copper THHN/THWN.

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Jake229

23 posts in 206 days


#14 posted 04-09-2020 08:03 PM

Thanks Captain! That was to just run the wire and install the panel. I am in SE Iowa. I will actually need to use grounding rods at the shop end. I will need 3 trenches to the new shop. One for electric, one for natural gas and one for cat 6 for internet. From what I hear, wireless don’t function well in metal buildings. I can only do it correct or over. Correct is definitely easier and cheaper. Take care, and be well!

-- Be safe out there

View CaptainKlutz's profile

CaptainKlutz

3347 posts in 2298 days


#15 posted 04-09-2020 08:47 PM

I installed enough cat wire to detached rural metal buildings to suggest one tip:
Even if you use conduit, you want use outdoor rated direct burial CAT6 cable. It is not cheap, but anything else has always created issues IME.

Every time I let my family member (or friends) buy the cheap indoor Cat wire for a new run the barn/shed; have remove and pull proper wire ~5 years later. The indoor stuff doesn’t like sitting in water/condensation that collects in underground conduit. The cheap indoor wire also doesn’t like being pulled trough conduit, and as the cable degrades over time it gets noisy/lossy to point it needs replaced. Nothing more frustrating than bad internet connection.

Due how technology changes, have been using large 1.5” conduit for low voltage, and running a pulling wire rope with 1st wire and every new wire run into conduit. Advance planning to have extra space and new pulling wire in place will save you ton of issues later, when stuff happens. And it always happens! DAMHIK

BTW – For one long distance install, it turned out to be cheaper to use directional antenna 5G wifi repeater on wall of each building, with network switch in remote building; than it was to run conduit and connect to main house internet. We had 4 bars signal level even during rain storms. The cost of outdoor directional systems has come way down in last couple of years.

Best Luck!

-- If it wasn't for bad luck, I wouldn't have no luck at all, - Albert King - Born Under a Bad Sign released 1967

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