grounding questions

[kaffine]

Well I found that my house has no ground. I am thinking it was grounded through the water line when it was built but they switched over to PVC when they connected to city water.

My plan is to install 3 ground rods 5/8"x8' 16' apart either in a line or in a triangle depends on how easy the trenching goes. I will be using exothermic welds to attach 2 gauge stranded wire to the ground rods. I will also be bonding to the copper water pipe undergroudn just before it enters the house.

Does the ground cable need to be in conduit as it comes up outside to the main box?

How deep does the cable need to be burried between the ground rods?

What determines if I want to use tinned copper or bare copper wire?

I figure my shop probably doesn't have a ground rod either. Will the shop require 2 ground rods or will it just need 1? It is feed with 4 wires from the house and is 40 feet away from the house.

Thank you.

 

[Gooch]

Only need 2 ground rods. only need to use #6. Bare is fine. Solid Copper is fine. Doesn't need to be in conduit, not sure if table 300.5 applies to GEC's or not. Someone that has their book handy will come by before I get a chance to look.

 

[Falcon67]

When my utility fixed the ground on our house, they used 2 8' rods 6' apart with #4 copper clamped to the rods. It's buried maybe 2" at most but it's right next to the foundation. I would do the same for the shop - 2 rods, 6' apart.

 

[rockwithjason]

livin in hendertucky huh? cool! i work for the city in utility support. use #4 solid bare copper, untinned. bury the wire at 18in minimum and 24 for safety. if you do enclose the wire in conduit, use pvc and strap it about a foot from the box and every 4ft after. if the garage is attached there is no need for a rod. if the building is detached you will need a rod. i believe 250.64(b) is controlling here, if not i will be corrected shortly.

 

[Charles (in GA)]

8 AWG and smaller grounding electrode conductors MUST be installed in RMC, IMC, RNC, or EMT or cable armor.

6 AWG grounding conductor not exposed to physical damage may be run along the surface of building construction without cover or protection so long as it is securely fastened to the construction.

4 AWG and larger grounding electrode conductors must be protected where exposed to physical damage.

If you use a metal conduit to protect the grounding electrode, it must be electrically continuous from the enclosure where it originates to the grounding electrode. In addition, the metal conduit must be properly bonded using bonding bushings or equivalent at the enclosure and the grounding electrode (rod).

250.62 and 250.64 and sub paragraphs cover this.

Table 250.66 will tell you what size conductor you will need for the grounding electrode, based on the size of your largest ungrounded service entrance conductors.

Charles

 

[Gooch]

8 AWG and smaller grounding electrode conductors MUST be installed in RMC, IMC, RNC, or EMT or cable armor.

6 AWG grounding conductor not exposed to physical damage may be run along the surface of building construction without cover or protection so long as it is securely fastened to the construction.

4 AWG and larger grounding electrode conductors must be protected where exposed to physical damage.

If you use a metal conduit to protect the grounding electrode, it must be electrically continuous from the enclosure where it originates to the grounding electrode. In addition, the metal conduit must be properly bonded using bonding bushings or equivalent at the enclosure and the grounding electrode (rod).

250.62 and 250.64 and sub paragraphs cover this.

Table 250.66 will tell you what size conductor you will need for the grounding electrode, based on the size of your largest ungrounded service entrance conductors.

Charles

250.66(A) says for rod and pipe electrode, that the GEC need not be sized larger than 6awg copper of 4awg alum

 

[kaffine]

Thank you. Looks like I will have a bit of overkill on the ground wire.

rockwithjason : How are you? Looks like there are a few people from the area on this forum.

 

[rockwithjason]

doing well thanks! things are good at the job and life is good. hope you are doing well too