[ct0218]

"I need to run power to my shop from an unused 200A panel mounted on a service pole 60 ft from the shop building. That 60 ft will have to be buried, and it is another 50 ft inside to where I plan to put a 125A branch or sub panel. In the shop I have a 5 HP/30A 240V table saw, and a dust collector, also 240V, and it draws 8A. Other than a light or two, that is all that would be running at the same time. I would also like to add a 50A RV hook-up, but that would not be running at the same time as the shop. I planned to run the wire from a 60A, 80A or even a 100A breaker in the pole-mounted panel to the branch or sub-panel, with a 50A breaker for the RV, a 30A for the saw, and a 10A for the collector. Also, a few 15A outlets and a couple 4 bulb fluorescent light fixtures. What size wire is needed for the 110 ft run, and what type? I was concerned about voltage drop and that long run in conduit. I assume PVC conduit for the underground portion, but do I switch wire types and add a junction box where it enters the building? Is it necessary to add a ground rod near the sub-panel as an additional ground? The existing pole- mounted box supplied power to a home at one time, but it no longer exists, so there is very little current used now, just a few extension cords off a couple of external weatherproof outlets. I am capable of doing the work myself, and helped an electrician wire my last 2 homes, but I am certainly not an electrician. Thanks for your help."

[ct0218]

Anyone able to help me?

[tkrussell]

My answers are in red after your questions.

What size wire is needed for the 110 ft run, and what type? I was concerned about voltage drop and that long run in conduit. I assume PVC conduit for the underground portion, but do I switch wire types and add a junction box where it enters the building?

Beginning with a 100 amp breaker at the Main Panel, use #2 aluminum wire with XHHW insulation, pulled thru 2 " PVC Schedlue 40 conduit. You can bury the conduit and install it exposed inside the building. At the point the conduit rises at the building you can use a junction box, say 8x8x6 as a pull point. Need 3 #2 for the two hots and one neutral, and 1 #6 as the equipment ground.



Is it necessary to add a ground rod near the sub-panel as an additional ground?

Yes, any panel in a detached building needs at least one ground rod, check local codes as many require two. In the panel, the neutral bar must remain insulated. Need to add a separate equipment ground bar for the #6 and all equipment ground conductors from the branch circuits.

[donf]

TK,

I have some questions on this item for your consideration, please.

1) Since the run to the shop is coming off a 200 Amp, unused meter, doesen't the poster have to get permission from the power company to put a service lateral in?

2) Since this would effectivley be a "Service Entrance" run, and the NEC requires that the Main Panel be as close to the entrance of the cable, will the tranch have to dug the full 100' to where the main panel should be?

3) If the poster does not put the underground (XHHW) cable in conduit, shouldn't the trench be at least 24" deep or is that a question for the LHJ? <P.S. Here in Va. Beach, Va. the LAHJ requires a trench that is 18" deep to the top of the cable or conduit.>

4) Did I misread the poster's question?

Thanks in advance

[tkrussell]

Don the poster has a panel at the service pole. The feeder to the garage will be considered as a branch circuit.

Conduit is min 18", direct burial cable (USE or URD, not XHHW) is 24 inch min depth.

[donf]

TK,

Thanks, I read into the original poster's comments that he was connecting to a meter, not a service panel.

"Beginning with a 100 amp breaker at the Main Panel, use #2 aluminum wire with XHHW insulation" Your comment from above.

I checked with the electrical inspectors here in Va. Beach before I entered my comment.

They require 18" to the top of the cable or conduit. Probably because if you go 20", you hit water.

Actually I think you hit "Potable" water at about 20' and yard water at 12'.

[tkrussell]

Well, he said this:

"I need to run power to my shop from an unused 200A panel mounted on a service pole 60 ft from the shop building.

The 18 inch minimum depth comes for the National Electric Code Table 300.5 Column #1 Direct burial cable for a one or two family dwelling, cable must be at least 18 inch deep.

If not one or two family, then DB cable must be 24 inch deep.

I have no idea what the water has to do with anything.

Utility companies want their lines min 30 inch deep.

[donf]

TK,

The LAHJ gave me the 18" requirement.

Va. Beach, Va. has a very low water table. I just mentioned that because I was curious as to why the LAHJ did not want the cable down 24". In point of fact, they did not require a warning tape that there is an electrical line below the tape.

Their words, not mine.

[tkrussell]

While a warning tape may not be required, as the NEC only requires a warning tape above a service entrance lateral, a warning tape above any underground utility is a good idea.

This is why local codes should always be checked, as there are always local issues and reasons.