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Yet Another wire size question

FunfDreisig

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Feb 12, 2008
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413
I want to install a TEMPORARY electrical service while building my garage. I have 50 Amps of spare capacity at the 200Amp Main service panel on the pole (150 Amps are dedicated to our cabin). The Garage is 200+ feet from the pole. What wire size (and type) would I need to power a 50 Amp Subpanel (i.e. a construction panel for compressor, saws etc.).? And what type of wire is suitable for exposed runs?

Background:
I'm currently running my small compressor, table saw OR slide saw off of 2 100ft long 12 ga extension cords (end to end). The extension cord is plugged into a 20 amp GFI on the pole. This setup works. BUT... the extension cord runs across the driveway requiring me to unplug every time we use the driveway. And the 2 - 100ft cords just barely reach the end of the slab.

I am planning to pull the cable under the construction driveway in sch 40 PVC conduit* open at both ends and simply run the rest of the cable over ground. FWIW I live in the country and have NO permitting/code/inspections to deal with. BUT I don't want to do something stupid :)

Thanks in Advance

* the construction driveway is simple road base and I have a backhoe.
 
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rinny_tin_tin

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Dec 20, 2008
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Northern Virginia
I want to install a TEMPORARY electrical service while building my garage. I have 50 Amps of spare capacity at the 200Amp Main service panel on the pole (150 Amps are dedicated to our cabin). The Garage is 200+ feet from the pole. What wire size (and type) would I need to power a 50 Amp Subpanel (i.e. a construction panel for compressor, saws etc.).? And what type of wire is suitable for exposed runs?

Background:
I'm currently running my small compressor, table saw OR slide saw off of 2 100ft long 12 ga extension cords (end to end). The extension cord is plugged into a 20 amp GFI on the pole. This setup works. BUT... the extension cord runs across the driveway requiring me to unplug every time we use the driveway. And the 2 - 100ft cords just barely reach the end of the slab.

I am planning to pull the cable under the construction driveway in sch 40 PVC conduit* open at both ends and simply run the rest of the cable over ground. FWIW I live in the country and have NO permitting/code/inspections to deal with. BUT I don't want to do something stupid :)

Thanks in Advance

* the construction driveway is simple road base and I have a backhoe.

Run No 4 and include a disconnect at the site. If you go underground - bury the conduit at least 2 feet below. I'd go with 3-inch PVC Sch 40 conduit and plenty of lube. If you go above ground - use a steel messenger to support the cable at least 10 feet above ground , and make sure you use UV resistant insulation. Provide a drip loop at the entrance - you can use a peckerhead. You need to double check how you are going to run the cable - as with all that equipment, it could easily get in the way or get cut. Try not to run any of the cable unprotected, and make sure you mark it so there is no mistake, etc
 
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FunfDreisig

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Messages
413
Run No 4 and include a disconnect at the site. If you go underground - bury the conduit at least 2 feet below. I'd go with 3-inch PVC Sch 40 conduit and plenty of lube. If you go above ground - use a steel messenger to support the cable at least 10 feet above ground , and make sure you use UV resistant insulation. Provide a drip loop at the entrance - you can use a peckerhead. You need to double check how you are going to run the cable - as with all that equipment, it could easily get in the way or get cut. Try not to run any of the cable unprotected, and make sure you mark it so there is no mistake, etc
I really appreciate your suggestion but... that's a lot of money/work to replace two 100ft extension cords plugged end to end :)

I was looking for a relatively inexpensive temporary solution to replace the extension cords during construction.

FWIW the job site is on sloping terrain in the Texas Hill Country. Soil depth is measured in millimeters, so burial (except under the construction driveway) is out of the question. And remainder of the traverse of this line would take it over ground that sees NO traffic (foot or vehicle).

Thanks again - Funf Dreisig
 

rinny_tin_tin

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I really appreciate your suggestion but... that's a lot of money/work to replace two 100ft extension cords plugged end to end :)

I was looking for a relatively inexpensive temporary solution to replace the extension cords during construction.

FWIW the job site is on sloping terrain in the Texas Hill Country. Soil depth is measured in millimeters, so burial (except under the construction driveway) is out of the question. And remainder of the traverse of this line would take it over ground that sees NO traffic (foot or vehicle).

Thanks again - Funf Dreisig

I'm not sure how you are going to get around the 50A item and the need for a larger cable. As it is, the No. 4 is borderline @200 ft and 50 A wrt VD%. Maybe you don't need 50A after all! Since it is a temporary power tap or extension cord, many folks treat such as a non-fixed cable not subject to prudent over-current, fire and electric shock safety protection means. If you have a construction driveway - that means you are doing some grading and that means heavy equipment and likely crews of immigris running around. You are not looking at a big expense relative to what is going on over there -- spend the $100 and do it right. All you need is one accident and you will be pushing that worker around in a wheelchair on what used to be your property.

:lol_hitti
 

nadogail

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Coronado, CA
In my opinion the previous responder gave you his "Best Case" fix.

As I understand your situation; you are looking for a "better, but not necessarily good" fix to make your electrical service a little less inconvienient.

Before you do a temporary improvement, you might want to consider what your long term goals are. Can your temporary fix be a part of your final solution?

Consider a wooden cable protector, a bridge of sorts, to keep the traffic from driving on the cables.

Lay down a pair of 2X4's on the flat, about an inch apart to accomodate your cable, put plywood pieces across the gap and screw them down. If you use 2x6 lumber instead you can rip a bevel on both the outter edges to act like a ramp. You now have a cable protector, the lumber keeps the tires off the wires.

Larger guage wire would be nice, I am especially fond of an 8 guage extension cord I run my welder with (I bought the wire at Home Depot and assembled it myself) but you seem to be getting by with the 12 guage cord.

Rather than put a temporary conduit under what will be your permanent driveway, consider doing that part of the job only once and "Right the First Time". If it is only a temporary construction road and there are other plans for permanent roads and electrical service, than another solution would be in order.
 
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FunfDreisig

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I'm not sure how you are going to get around the 50A item and the need for a larger cable. As it is, the No. 4 is borderline @200 ft and 50 A wrt VD%. Maybe you don't need 50A after all! Since it is a temporary power tap or extension cord, many folks treat such as a non-fixed cable not subject to prudent over-current, fire and electric shock safety protection means. If you have a construction driveway - that means you are doing some grading and that means heavy equipment and likely crews of immigris running around. You are not looking at a big expense relative to what is going on over there -- spend the $100 and do it right. All you need is one accident and you will be pushing that worker around in a wheelchair on what used to be your property.

:lol_hitti
We really aren't subject to standard worker risk issues because the "workers" on this project are me and my wife:) We built our own construction driveway with the box blade on my tractor. That is the extent of heavy equipment that will be on site. Our property is a natural grassland savanna . Once off the driveway you are in waist high native grasses in terrain too rugged to drive a vehicle.

I think your AMP point is right on target. We HAVE 50 amp capacity at the pole but we only NEED 20 amps to run the compressor, saws etc. during construction. So maybe we install a higher rated sub-panel at the garage (say 125 amps, that would be useful later) BUT only feed it using a 20 or 30 amp breaker in the main panel at the pole. This should keep us from over loading the 200ft of cable.

Thanks again - Funf Dreisig
 
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FunfDreisig

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In my opinion the previous responder gave you his "Best Case" fix.

As I understand your situation; you are looking for a "better, but not necessarily good" fix to make your electrical service a little less inconvienient.

Before you do a temporary improvement, you might want to consider what your long term goals are. Can your temporary fix be a part of your final solution?....
Good points. That is what I'm trying to do.

All of the stuff at the garage end will be re-purposed once we install the under ground cable and surface transformer that will service the garage and ultimately the house. For example the "construction" sub panel, breakers, etc. will be re-purposed into the sub panel for the rain water collection/transfer pumps, UV light etc. The only part I can't easily re-purpose is the 200ft of electrical cable. So that is why I'm trying to go low budget on this item. But not so low budget as to create a problem.

FWIW It's actually pretty easy for me to drop a stick of sch 40 conduit under the construction drive. Although part of the main drive will use this section of the construction drive, it is not where the under ground cable for the surface transformer will be located. So doing this "right" doesn't help in the long run.

I'm thinking of running 200ft of 6ga UF-B and just laying out on the ground. I may be able to re-use 70 ft of it later when I connect this sub-panel to main panel which will come in the other end of the garage.

Thanks for your suggestions - Funf Dreisig
 
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tfi racing

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Cedar,BC
Do you have anyone in your area that deals in used electrical equipment or salvage?They may have some suitable used #6(or#8) cabtire(SOW) or teck that could be used as a temporary power cord for the sub panel.After the project is done,just sell off what you can't use.
 

walrus

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Maine
If all you want to do is run some corded tools, why not get 250 ft of 10/3 UF, share the neutral between a couple of GFIs, hook it to a 2pole 20 amp breaker. You'd have 2 circuits over there, with a little compensation for the distance. it would be temporary and crude but it would work
 

VHF

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Oct 27, 2008
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NW Wisconsin
I would second the 10/3 as walrus suggested. That would give you two 120VAC 20A circuits at the construction site. Plug your compressor into one and whatever saw you are using into the other and you are good to go!
 
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FunfDreisig

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If all you want to do is run some corded tools, why not get 250 ft of 10/3 UF, share the neutral between a couple of GFIs, hook it to a 2pole 20 amp breaker. You'd have 2 circuits over there, with a little compensation for the distance. it would be temporary and crude but it would work
That's a simple solution that just might work to replace the extension cords:)

I'd like a little more than that though. The garage is now framed and mostly dried in. I still need to build the 14 sliding garage doors, etc. It would be nice to have a sub-panel w/ a few wal plugs etc. that I could begin using as I complete the project.

Thanks - Funf Dreisig
 

35mastr

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If you are already dry.Then just plumb out the proper pipe and wire to your new panel in the shop and start fresh. With a couple of wall plugs that you are going to be using anyway in the future.

I would not even bother with any temp cords at this point if you are pretty water tight.
 
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FunfDreisig

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If you are already dry.Then just plumb out the proper pipe and wire to your new panel in the shop and start fresh. With a couple of wall plugs that you are going to be using anyway in the future.

I would not even bother with any temp cords at this point if you are pretty water tight.
"Dried in"is a relative term. The current status is similar to the attach image only not quite that good :) I'm working on the car port posts. GLULAM and rafters this week. The roof is still tar paper and there is only ONE window installed. IOW it is dried in as long as it only drizzles - vertically. BTW those huge holes in the walls will be covered by 14- 4'x9' sliding garage doors.

FWIW the main electrical feed will(eventually) be from the right hand side of the image after we install the under ground electrical service and transformer for the garage and residence. Currently the only power available is a 15 amp circuit at the septic just to the right of the image (14-3 romex). Or 50 amps of spare capacity at the existing meter/panel on a power pole 200 ft to the left of the image :(

What I am working on is an interim power solution for the garage during construction. So that I can finish it, and fill it up with the two cars, parts, and other stuff in 3-10x20 storage bins that cost $210/mo. Only then can I begin working on the main residence including digging the 300'+ of trenches to install the under ground service for both the garage and main residence.

Funf Dreisig
 

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FunfDreisig

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Do you have anyone in your area that deals in used electrical equipment or salvage?They may have some suitable used #6(or#8) cabtire(SOW) or teck that could be used as a temporary power cord for the sub panel.After the project is done,just sell off what you can't use.
Following up on your, walrus and VHF suggestions... I called around and found some 8-3 Tray Cable for $0.71/ft :) The electrical supply house says it is UV resistant. SO...

I bought 250 ft of 8-3 Tray Cable and plan to install it as a temporary "over ground" feed for a sub-panel that I will eventually re-purpose as the rain water system sub-panel. I'll feed it from the main panel (on the pole) with a dual 30AMP breaker to reduce the chance of overloading the wire. FWIW the rain water system pumps, UV light etc will be located at the left rear of the previous image. Which just so happens to be the ONLY part of the garage that is "dried in" :)

Funf Dreisig
 
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