sub-panel in barn...again

Inspector507 · Feb 23, 2005

Then you do not have to run 4 wires unless you want to. If you run 4, no grounding electrode is needed.

edit.......
At least according to the 2002 and 2005 NEC®. Your local codes may vary.

_RaT_ · Feb 23, 2005

As the Inspector says, "your code may vary". Ours would require 4 wires. The ground at the barn may set up a situation of disimilar grounding potential and thereby actually develop a voltage to ground between the 2 grounds. Thats providing I understand it correctly, it gets complicated. Running 4 wires is safe. A 2" conduit is overkill.

fractal · Feb 23, 2005

The only thing I will add to the discussion is .. labor around here is expensive. It would be most unfortunate if you found yourself digging that ditch in a year or two because you did not provide enough power. I would consider a 50 amp circuit the minimum I would run to a full fledged shop/barn. That will let you run a basic 220 buzz box welder. I do not have the charts in front of me but I believe #6 is good for 50 amps at 150 ft.

You said you were going to put a 40 amp 220v breaker in. Your wire is a little light for 40 amps but it looks like you are only planning on deploying 20 amps of it assuming you put each of the 20 amp breakers in your barn on different legs which would be the smart thing to do.

Might I suggest you price check wire at your local electrical store and decide where the price starts to hurt. It does not cost THAT much more to run a size or two bigger than you think you need today to make sure you have capacity for tomorrow.

I know I sure would not put 14 shop outlets on a single 20 amp circuit, and I hope you realize that you are not supposed to have lighting on the same circuit as tools ... oops, just turned on the shop vac and blew the breaker taking out the lights right after starting up the saw so there is this sharp piece of metal spinning inches from my fingers and it is dark...

As for ground rods. The code on what you are required to do changes often. If it were me, I would run 4 wires AND I would drive a local ground rod. This is not (currently) required by code but it is not prohibited.

EddieWalker · Feb 23, 2005

Running water and power in the same trench may or may not be legal in your area. Lots of places it isn't allowed.

I would run it in a seperate trench. If the water line ever breaks, then you will have to dig it up and work around the power lines.

Turning off the power will protect you, but there's no gurantee you won't damage the power lines when digging up the water line.

I know some peopel who put them on the oposite edge of a two foot wide trench. That might work better, but still not ideal.

Mark you water line with a copper wire also. It's real easy to forget the exact location ten years from now.

mathey · Feb 24, 2005

I appreciate all the responses!

I've spoken to lots of different people with many diverse backgrounds and have gotten info that has been all over the map.

I will go to the county electrical inspector and he will have the final say on my plans...since he's the one that's gotta sign on the dotted line anyways.

It appears that electrical wiring is alot like Geometric Dimensioning and Tolerancing...its subject to interpretation!

Thanks again for your time and insight!

Junkman · Feb 24, 2005

( .....................It appears that electrical wiring is alot like Geometric Dimensioning and Tolerancing...its subject to interpretation! )

Add hydraulics to that list also..... /forums/images/graemlins/grin.gif /forums/images/graemlins/grin.gif /forums/images/graemlins/grin.gif /forums/images/graemlins/grin.gif /forums/images/graemlins/grin.gif

srs · Feb 24, 2005

( Running water and power in the same trench may or may not be legal in your area. )

Eddie, I too do not know if running water and power in the same trench is legal, but he will run a 3/4" water line inside a 2" PVC pipe. So I guess his thinking is if the water line should ever break he could just pull the 3/4" line out from either end. I personally would dig a separate trench just to be on the safe side.

SPIKER · Feb 24, 2005

( No Spiker, you do NOT have to run 4 wires

Copied with permission from the 2005 NEC® website:

 (2) Grounded Conductor. Where (1) an equipment grounding conductor is not run with the supply to the building or structure, (2) there are no continuous metallic paths bonded to the grounding system in each building or structure involved, and (3) ground-fault protection of equipment has not been installed on the supply side of the feeder(s), the grounded conductor run with the supply to the building or structure shall be connected to the building or structure disconnecting means and to the grounding electrode(s) and shall be used for grounding or bonding of equipment, structures, or frames required to be grounded or bonded. The size of the grounded conductor shall not be smaller than the larger of either of the following:

(1) That required by 220.61

(2) That required by 250.122
 )

this is true but you missed the part where in section 250.32 A it states that if "where there are no existing grounding electrodes, the grounding electrod(s) required in partIII of this artical shall be installed." there is an exception but that only pertains to a single branch circuit. and he wants 220.

part III is on page 70-104 (in nec2002) states what type of ground rods and or piping is useable.

section 408.20 states that " grounding of panel boards panelboard cabinets and panelboard frames, if of metal, shall be in physcal contact with each other. and shall be grounded. ..." but that is slightly off topic: still I can't find the section where the netural & gound in second panel should be disconnected. the above was fast and simple to locate. and the new 2005 may not have it in there anymore.

still it is wise to defer to the local inspector /forums/images/graemlins/wink.gif even if he is # 57 /forums/images/graemlins/laugh.gif

Inspector507 · Feb 25, 2005

Spiker, after re-reading my posts, I did make a mistake when saying that a grounding electrode is not required, it would be. But you still do not have to run 4 wires /forums/images/graemlins/grin.gif