Electrical help for wiring to a building.

[Gary H NC]

I am building a new shop behind the house.16x24

I know how to run all of the wiring inside the shop but will be installing a sub panel from the power coming from the house.

I have about an 80 ft. run from the house to the shop.
I need 220 and 110 power.
The only 220 is for an air conditioner.Its a wall unit 18,500 btu.

Lowes and Home Depot have me confused as to what wire to use for my under ground run in pvc pipe.

One guy showed me some stuff at 3.74 per foot! OUCH!
The other place showed me some stuff called 2-2-2-2 aluminum wire.
It was about 2.80 per foot.

Anyone know of a reasonable priced wire that will handle the power and amps?
I was thinking 40 amp main breaker but the guy at Lowes said 60 amp...

All confused now...

 

[zach103]

Re: Electrical help for wiring to a building.

i dont think it matters.. we ran some 110 wire from an existing switch to that gray flexible (i thnk pvc) we ran the wire inside that and its been fine for about 5 yrs so far

 

[Gary H NC]

Re: Electrical help for wiring to a building.

Thanks Zach,

I think i just need to know the gauge wire to use.They told me i need 4 wires plus the ground.
The big stuff Lowes showed me was over kill i think.It was as thick as the main service power coming to our house...

 

[arks]

Re: Electrical help for wiring to a building.

'UF' romex is rated for outdoor/ underground use. You would need a minimum of 10/3 UF to power your shop.
Another idea (since you have a buried pipe) is to use separate conductors. When powering my shed I used 4 lengths of #10 solid THHN wire (3 wires + ground). The reason I used THHN was because I also ran an airline in the pipe and needed as much space as possible. The downside? You have to run conduit to the nearest junction box at each end.

TIP: when snaking a pipe ALWAYS add a new pull string. You'll thank yourself in the future!

 

[captmello]

Re: Electrical help for wiring to a building.

that big aluminum wire is the way to go. I'd skip the conduit and just bury the wire in the ground.

I forget the names of the sizes, but you don't need super heavy stuff. Seems to me there is some thats good up to 100 amp. Thats probably what you need.

Assuming you're pulling all the correct permits and tax grabs, you could ask the electrical inspector.

 

[Gary H NC]

Re: Electrical help for wiring to a building.

Thanks guys,

I think the real thick aluminum wire came in a roll with 2 black,1 black and white and a green wire.
I will run it in conduit either way so if i ever need to upgrade i can.
A couple extra pull strings is a good idea too.
I need to get cable and phone lines through it too.

I have a electrician to hook the lines and the sub box up but he is out of town and i wanted to get the wire in the ground.

No permits....

 

[mla2ofus]

Re: Electrical help for wiring to a building.

If you use the alum., be sure to use the antioxidant on the ends of wires making connection to copper or alum. lugs.
And w/ alum. don't be afraid to go one size larger than you think you need. It really heats up fast if overloaded.
Mike

 

[Gary H NC]

Re: Electrical help for wiring to a building.

Thanks,

I found the #10 solid THHN online for 39 cents per foot!
Its from an electrical supply house in PA.

Just wondering if 10 AWG is heavy enough for that long of a run.

 

[j_martin]

Re: Electrical help for wiring to a building.

Thanks,

I found the #10 solid THHN online for 39 cents per foot!
Its from an electrical supply house in PA.

Just wondering if 10 AWG is heavy enough for that long of a run.

What determines the size of the wire is the load, and the distance. Another factor is that it must be rated to carry the current that can be supplied by the feeding circuit breaker. It's all calculated. Also, any installation must meet the National Electrical Code. (NEC) It's a safety issue.

You cannot run power and communications circuits in the same pipe. It's both illegal and dangerous. The exception is communications in a machine setup and then the communications has to run through 600v wire, not class 2 like telephone wire is.

I have asked pointed intelligent questions at places like Menards, and have gotten the most ridiculous answers I can imagine. I guess they are trained to sell something, even if they have no clue what they are talking about. Home depot, because of their policies, is likely to be a bit better, but still not expert my any means. That's not where to ask what you need to do a job. You determine what you need, and you might even have to explain that to them to buy it.

For a good handbook, and also tutorial on electrical wiring, designed for the homeowner, go to your building supply store and get a copy of Richter's Wiring Simplified. Be sure to get the latest one which is based on the 2008 NEC.

BTW, the 10/3 UF feeder will supply your air conditioner, and a couple of 15 amp 110 volt circuits, like a very small compressor and 1 or 2 power tools and a few lights. Might be all you need, but if you're going to get serious about anything, it's pretty light.

hope it helps
John

 

[arks]

Re: Electrical help for wiring to a building.

BTW, the 10/3 UF feeder will supply your air conditioner, and a couple of 15 amp 110 volt circuits, like a very small compressor and 1 or 2 power tools and a few lights. Might be all you need, but if you're going to get serious about anything, it's pretty light.

hope it helps
John

John-
Gary's found #10 THHN, not 10/3 UF. THHN can take a higher amperage load than UF due to its ability to dissipate heat more efficiently.

My shed's 110' from the house and the subpanel has 6-120V 15A circuits. Never popped one yet.

 

[Bifflefan]

Re: Electrical help for wiring to a building.

Option 1:
Go to an Electric Supply place in your town, Ask them for the correct wire size for the distance, then you can buy it where ever.

Option 2:
You can also ask the building inspector what he would like to see for a size. As he is the one that has to sign off on it.

If your doing like we did and not haveing elec. till after the inspections are done, then go with option 1

 

[Gary H NC]

Re: Electrical help for wiring to a building.

Thanks for all of the info guys.Much appreciated.

I have decided not to run phone line.The cable for the TV i have is the flooded underground type so i can bury it without using conduit.

I will keep the power by itself.

As long as i have enough power for the AC unit,lights and hand tools i will be happy.

 

[i386]

Re: Electrical help for wiring to a building.

I don't think getting ahold of some direct burial phone cable would be too expensive. The trick is to get some with as few pairs as possible.

I still have some connections at the telecommunications place I worked for. If you're interested, let me know how many feet you need and I'll see what I can do.

 

[Gary H NC]

Re: Electrical help for wiring to a building.

I don't think getting ahold of some direct burial phone cable would be too expensive. The trick is to get some with as few pairs as possible.

I still have some connections at the telecommunications place I worked for. If you're interested, let me know how many feet you need and I'll see what I can do.

Thanks i386,

I may have some now that i think of it.I will have to check over at my storage unit but i think i had part of a 1000 ft roll left.
I know i have 2 rolls of underground RG-6 for TV.

Thanks for the offer...

 

[windsors03cobra]

Re: Electrical help for wiring to a building.

Aluminum wire, ick.

 

[Gary H NC]

Re: Electrical help for wiring to a building.

Aluminum wire, ick.

That was my thoughts too.....

Going with the #10 i found online,copper solid wire...unless someone tells me its not big enough....

 

[jlinder]

Re: Electrical help for wiring to a building.

The suggestions of getting the NEC code and checking with the electrical inspector are great ideas. If you can get the inspector to tell you what he will reject it will certainly save you a lot of headaches.

There are a lot of factors that affect how big it has to be. The NEC book has different ratings if the wire is UF, THHN, in free air, buried, in conduit, copper vs. aluminum, how full the conduit is, etc. There are a lot of people out there who are happy to give you answers who don't know all these factors.

For example, aluminum has a lower rating than copper, if you bury THHN in conduit that affects the ability to dissipate heat. You probably have a big enough conduit but when you start filling a conduit above a certain level you need to derate the capacity due to heat. If you have anything that draws a constant current like a heater you need to derate to 80%. How long is the run. Probably not a factor but could be.

All these factors become important when you are trying to run the minimum guage needed. On the other hand you can avoid a lot of questions if you just go a little bigger. If you just go a little bigger you avoid concerns that you may have goofed.

You also need to bury the cable a minimum distance below ground. Not sure (I don't have a copy of the NEC 2008 with me) but I have seen either 12" or 24" as the mimimum.

Start with figuring out what you need. Maybe you have done this, maybe I missed it, but I did it looked like you had questions. Consider answering these questions:

You mention air conditioner. What amp breaker does it require? Do you have concerns that you may need larger.

Do you think you will want a heater. Doubt you would run air and heat at the same time but make sure you have enough for a possible future need (heaters circuits also need to be derated to 80%).

How many outlets/circuits do you want?

How many lights will you have? Any outside lights?

Once you get all these answered you know the breakers you need and this will tell you the wiring you need.

Remember, you are doing this once (you hope), it costs money, it is worth spending the time to know that you did it right.

 

[Gary H NC]

Re: Electrical help for wiring to a building.

Thanks Jlinder,

I will talk to my electrical guy this week.He is also an inspector.
I would rather pay a little more and go heavy on the wire size.
The code here is 24 inches deep.I may need to rent a ditch witch..
Been digging by hand...its a killer.

Never know,I might end up wanting a welder later down the road and more tools.

Right now i will have about 6 outlets,the AC,At least 3 sets of florescent lights and an outside motion light.
I planned on splitting the outlets on 2 breakers,1 breaker for lights and a breaker for the AC.
An electric heater will probably be used once in a while too.

 

[Numlaar]

Re: Electrical help for wiring to a building.

That aluminum wire is basically junk... but if it is the proper gauge than you can still use it.

For it to meet electrical code, you need to run the appropriate gauge wire that will meet the total Amperage requirement of the sub panel you are installing...

For example, if you are putting in a "100 Amp" sub panel, then you MUST Run 100amp servicable wire to the panel (whether or not you plan on using the entire panel's breakers or not).

Anything less than the rated amperage for the panel is below code and a fire hazard.

Also if you are "jumping" off the main panel to feed the sub panel (instead of running the new line directly off the meter lugs), then you would also need to up the main lines feeding the main panel to include enough amperage for both the main and sub-panels... this can get pricey depending on how big your main panel is, and how many amps you intend to send to your sub panel. Once you start getting over 200amp total service, you're looking at going to a specialty electrical store versus the depot or lowe's.

For your 220, there are two ways to do it:

first way is with a 3 bar sub panel.. The sub panel will have the 3rd bar in the middle of it so you can connect a 220 breaker to it. You have to be careful about where you connect your breakers... so you dont put 220 where you dont want it.
second way is, you can use the double breaker style that makes it 220 off of a 2bar system. each breaker is 110, then a special double breaker to make it 220.

Also second everything Jlinder said... you need to know the number of circuits for what you plan on installing, the amp rating for the items, and install a big enough panel to service it all... then of course feed the panel with the appropriate gauge wire. (as mentioned above).

You can use romex inside the shed once you get done... 14/2/G for 15amp service circuits, 12/2/G for 20amp service.

I am sure a lot of people have run "whatever" without any problems... (popping breakers, fires, etc.), but the question is, whether you want to do it right, and meet code or not. If you do it right, you have piece of mind both for safety and the law.

 

[Bigprairie1]

Re: Electrical help for wiring to a building.

I'd pass on the aluminum wire. Although it seems cheap....remember you always get what you paid for.
As for the correct wire for that distance....well it has two factors...what load(s) you think you might put on that service..and what the code believes you probably will put on it as some point.
I installed a hot tub about 2 years ago at our house. It has (2) pumps (3hp and 4hp...I think) and a heater. It required about 60-70 feet of wire. Code said....60 amp service (with GFI main breaker) and a #6 wire...yep, #6.
Are you thinking of running a compressor Gary? Power tools? (high amperage draw), how many lights? Table saw? +...the air conditioner of course. Check to see how many amps it pulls...noting that it pulls a lot more when first turned on then look at some of the amperage requirements of your current favourite (and future?) power tools. This might help with the decision.
My guess is #8 wire for that distance as per code....less without code.
Our burial code says that if it is buried under a 'non-vehicle' path depth can be 18"-24" (burial code type wire). If it is under a vehicle path (ie: driveway) it has to be something like 32"...more or less.
I would definitely put it in conduit with a fish wire included. That way if you ever had to or wanted to change the wire (upsize for something new, shop expansion, etc, etc) you can just fish a new one through rather than redigging the yard.
My two bits, good luck and keep us posted on this.
BP
ps 1: 'don't forget to include a mini-bar fridge in the calculations!!
ps 2: The wire should have 2 hots, a neutral and a ground wire in it for that application