building wiring question

[Iowa Dave]

I'm wiring in an RV box on the side of the tractor shed. The subbox I'm coming off of is not grounded other than to the 220 neutral. Should I put in a grounding rod or not. I'm not clear on when a ground round should be installed.

Dave Hopkins

 

[Sparktrician]

You should add a ground rod at the sub panel in your barn. Drive a 5/8" x 8' rod, and run a #4 copper ground wire from your panel to the rod. You will need to add a ground bar in the sub panel to land the #4 copper to. Once you install the ground, it is advisable to move all equipment ground wires from the nuetral bar to the ground. DO NOT BOND THE NUETRAL AND GROUND TOGETHER!!!! From your sub in barn to RV disconnect, run 4 wire cable. If using Romex (typical house wiring) you will need 6/3 with ground copper. You can use aluminum, its cheaper but I would use copper in my barn. Once again, at Rv disconnect, do not bond nuetral and ground!!!!

 

[Iowa Dave]

OK. THis was a hog farm with split meters. House and garage on one meter and everything else on the other. It looks like some ground rods were installed and later disconnected. Should I ground every building? I've read some threads on here that have me really confused. I know enough to wire in lights and outlets, but the overall system of grounding is beyond me

Thanks Dave.

 

[Anonymous-0]

If the subpanel does not have an equipment grounding conductor coming from the main panel that feeds it then you need one.Driving a rod if you only have a three wire feed to that subpanel may not allow breakers to actually trip when needed.

 

[buickanddeere]

It sounds like there was a tingle voltage problem shocking the hogs.
Somebody went around "willy nilly" disconnecting grounds. Instead of using insulated white conductors to carry current and bare copper to ground equipment.

 

[KEB1]

Each feed from a separate meter is grounded to earth via a rod (or several rods connected together) exactly ONCE, at the first panel. Any subpanels must have an isolated grounding conductor carried back to the first panel which is separate from the neutral. A "grounded" conductor (neutral) and a "grounding" conductor are not the same thing, and they only connect together at one point.

You actually create a hazard when you have more than one connection to earth in a single feed. Contrary to popular belief, there is actually significant resistance between a ground rod and the "earth", and it is entirely possible to have a fault with enough current to provide a fatal shock and not blow the breaker due to this resistance.

Keith

 

[Anonymous-0]

I have read it is incorrect to drive rods at outer buildings.However on several websites I see that advice.I dont see it in the NEC.It is often hard to argue electricity on a web forum and many inspectors give bad info also.I know a guy who tests ground rods by running a number 12 AWG conductor off a 20 amp breaker to the rod then takes an amprobe reading off the wire ,using ohms law caculates the rods resistance.The fact that the breaker does not trip but allows for a reading tells me something.In the code the rod is only supplemental grounding anyhow.On another note poor grounding is killing many of our soldiers in Iraq and has burnt down ten buildings on a Marine base.Interesting and tragic. EC&M had an article about rods electrocuting a dog in an outer building.Rods can also be responsible for electrifying swimming pools and probably should not be driven in such locations nearby.I was taught grounding is always "targeted" to the main service.Grounding bullseye.I just commented because you seem to be from this school of thought.

 

[GA Dave]

I've not been doing wiring for many (20 or so) years but back then the neutral and ground were bonded together at the point of entrance only. Feeders to subpanels were wired with their own ground conductors. Same as from the subpanels to RV recepticles. Note that the National Electric Code can change somewhat with each new edition. David.......

 

[504-2]

Dave I have to ask about 220v. RVs standard is 30 amp 115 volt no 220. Just thought I would ask, no disrespect intended.