What wire do I need?

[bjaspud]

I am planning on adding electrical power to my un-powered 2 car storage garage. The garage is 160 feet from the house. My plan is to rent a trencher and bury pvc pipe between the house and garage.

My question is, what gauge and type of wire should I run?

I 'think' I'm going to have either 30 or 50 amp service.

All I'm looking to hang 4 ceiling lights, one work light over the workbench and a couple of quad outlets.

All of the big electrical draw tools will remain in my main garage.

Wire recommendations??

 

[tyjoja]

I used two 4 gauge with one 6 gauge for a ground on something similar

 

[dogdog]

most ppl here use 2-2-2-4 UF cables for hot hot neutral and ground

I used 1 1/2 Rigid metal conduit and 4 #6 THHN CU wires for my sub-panel. in case you run 240 some time later.

 

[pattenp]

Because of the distance and even though you are talking only 50 amps I suggest aluminum 2-2-2-4 mobile home feeder. The mobile home feeder is a pre-assembled cable and is common and is relatively cheap compared to copper. The minimum size wire you should use is #3 aluminum THHN/THWN for 50A at 160 ft..

 

[Bib Overalls]

Figuring 180 feet #3 aluminum would support 50 amps. A better and cheaper solution would be to use 2/2/2/4 MHF (aluminum mobile home feed) which will support 70 amps. MHF is a direct bury cable which means you will only need conduit where the cable comes out of the ground. Use a 100 amp service panel in the garage with a disconnect. You, or a future buyer will eventually find a use for the additional power. MHF is competitively priced at big box stores like Lowe's and Mernards ($1.47 a foot).

Your described load could be handled with one 20 amp circuit. At 180 ft this load could be handled with 6/2/wg copper UF (underground feed). You would save the cost of a load center but your wire cost would be $2.78 a foot (Lowe's).

My mother-in-law put two freezers in an outside shed fed with one 15 amp Romex circuit running, for the most part, underground. She could never understand why the breaker kept tripping. Brother-in-law said "I'll fix that for you mom." He put in a 30 amp breaker. One night, while we were visiting, the section of wire that ran from an outlet in the kitchen, out the back door, and down the foundation fried. Spectacular. Tried several times to explain electricity and wire size using the water and pipe analogy but to them, electricity was electricity and dangerously cheap was just good enough.

In my own case, I originally ran 60 amps to my 30' x 40' shop. This summer I am going to upgrade to 100 amps using MHF. The 60 amps was OK until I added a heat pump and started doing a bit of welding. A lesson learned the hard (and expensive) way.

 

[MN4x4]

Good advice here.

In addition to what was mentioned above, another reason to use the Mobile Home Feeder is that ANYTHING you use inside conduit in the ground must be rated for direct burial, even tho it's inside your conduit. I direct buried my power cables, but ran conduit for my Cat 6 and coaxial (TV) lines. Even though they are inside the PVC conduit they must be rated for direct burial as well. Even my phone line from the street had to be burial rated.

Use the money you save from not installing conduit to put in a LARGER feed than you think you need. I would recommend 100 Amp service as a minimum, even if you don't have a need for it now. Upgrading later will cost you double or triple compared to doing it the right way now.

 

[Norcal]

Good advice here.

In addition to what was mentioned above, another reason to use the Mobile Home Feeder is that ANYTHING you use inside conduit in the ground must be rated for direct burial, even tho it's inside your conduit. I direct buried my power cables, but ran conduit for my Cat 6 and coaxial (TV) lines. Even though they are inside the PVC conduit they must be rated for direct burial as well. Even my phone line from the street had to be burial rated.

Use the money you save from not installing conduit to put in a LARGER feed than you think you need. I would recommend 100 Amp service as a minimum, even if you don't have a need for it now. Upgrading later will cost you double or triple compared to doing it the right way now.

That is incorrect, the NEC defines a wet location as any conduit underground or outdoors, the cable must be rated for wet location, such as THHN is for dry locations, THWN is rated for wet, dual rated THHN/ THWN can be used for either.

Conduit is cheap insurance.

 

[MagKarl]

When you're sizing the wire to feed your subpanel, how much voltage drop do you accept? Which types of equipment you might have in a shop are most sensitive to input voltage and why? I'm going to be wiring my pole barn this summer.

 

[Kingcreek]

Why pvc pipe instead of conduit?
I had a guy come in and bury flex conduit with a walk-behind vibe knife and charged me $1 per foot including the conduit. All I had to do was a few minutes of spade work at each end.

 

[pattenp]

Electrical rigid conduit can be PVC or Metal. We're not talking PVC plumbing pipe.

Why pvc pipe instead of conduit?
I had a guy come in and bury flex conduit with a walk-behind vibe knife and charged me $1 per foot including the conduit. All I had to do was a few minutes of spade work at each end.

 

[pattenp]

No more than 3% voltage drop is recommended by the NEC. Motors don't like voltage drops. Can cause them to over heat.

When you're sizing the wire to feed your subpanel, how much voltage drop do you accept? Which types of equipment you might have in a shop are most sensitive to input voltage and why? I'm going to be wiring my pole barn this summer.

 

[Beemer533]

Why pvc pipe instead of conduit?
I had a guy come in and bury flex conduit with a walk-behind vibe knife and charged me $1 per foot including the conduit. All I had to do was a few minutes of spade work at each end.

I'm assuming that you had this done for an irrigation system? The Op is running conduit for electrical service.

 

[MN4x4]

Why pvc pipe instead of conduit?
I had a guy come in and bury flex conduit with a walk-behind vibe knife and charged me $1 per foot including the conduit. All I had to do was a few minutes of spade work at each end.

What size was the conduit?
Was the conduit rated for electrical wires?
How deep was it buried when he was done?

I believe (somebody correct me if I am wrong) the current code is you must go at least 18" deep for plastic conduit, and 24" deep for direct burial cable.

 

[gungatim]

When I wired my polebarn, I ran 40 amp service about 150 ft. underground as you are planning. I found it was much cheaper to buy a single 300 ft. roll of red #4 (I forget which specific size I used) wire and cut it in two, then wrap the ends of one conductor the proper color where it enters the box. the neutral was a seperate spool of stranded copper as well. It was about half as much as buying the special all in one feeder. I did add a ground rod as well. Everyone told me it would not be enough power, but really, I can't do much more than run the fridge, Air compressor, lights and one tool at a time. I have never come close to blowing the main breaker.

 

[Kingcreek]

I'm assuming that you had this done for an irrigation system? The Op is running conduit for electrical service.

Nope. conduit for electrical service to an outbuilding.

 

[theoldwizard1]

Because of the distance and even though you are talking only 50 amps I suggest aluminum 2-2-2-4 mobile home feeder. The mobile home feeder is a pre-assembled cable and is common and is relatively cheap compared to copper. The minimum size wire you should use is #3 aluminum THHN/THWN for 50A at 160 ft..

+1 !

Plus MHF does not require a conduit EXCEPT above ground.

 

[rburke65]

Run 2" PVC conceit all the way and you will never be sorry! Go price it.Not that much.

 

[lotsoftools]

If you were my dad you would just use a long extension cord and then run it over with the mower later. But since you're not him, go with the advice above.