Electrical Sub-Panel Installation

[fastleft]

I am planning to install an electrical subpanel in my detached garage. I pulled a permit and now I just have to find the time to dig the trench and get to work. I have two things that I could use some help with.

1. Ground Rod Installation - I know that everyone says to drive them in with a 5# sledge hammer, but is that really feasible? I know that its going to take forever, but can it be done that way? Any other suggestions?

2. Drilling through house foundation - I need to drill one hole about 1 1/2" in diameter through the house foundation. I have a big Milwaukee hammer drill, but not a rotary hammer. I see that McMaster Carr sells a 1 1/2" diameter masonry bit with a 1/2" shank for about $30... do you think that would work? It only has a drilling depth of 4" so I would need to work from both sides. I've drilled a 1" hole in cement block in the past and that wasn't too bad. Any other ideas?

Thanks for any info
Tommy

 

[Davey4000]

1. I pounded two rods in with a sledge. I didn't hit any rocks though. It probably took 45 minutes or so...even with several rest periods. The hardest parts are the beginning and the end. The beginning because you have to stand on a ladder and it's floppy, and the end because the skin friction with the soil makes the going much slower.

2. I rented a rotary drill at HD for half a day at about $50. It took me longer to go get it and take it back than it did to pop the hole.

 

[nova65ss]

I used a tool designed for driving the rod it slips over the top and has a large weight that slams down on the top of the rod. Don't know what it's called but I can find out, my neighbor is a sales rep for Square D and got it for me. I went through the siding on my garage saved me the hassle of drilling through the concrete.

 

[LoneGunman]

Yeah a sledge will work, I lost track how many I have driven in NJ. I now live in FL, very easy ground rod driving.

Is the house foundation block or solid concrete/cement? If its block you can use a hammer to make your whole easily if you avoid the webs.

Just some general things from being an electrician:

If you are digging anyway run an extra conduit for low voltage, phone/data/cable TV

Make sure you do NOT bond the neutral bus to the panel enclosure and youll need a ground bus kit if the panel does not come with one. The neutral bus only gets bonded to the enclosure at the first means of disconnect.

 

[PAToyota]

I really recommend using one of these for the grounding rod connections: http://www.erico.com/products/plusoneshot.asp

Especially if you plan to have a welder, having a good ground is essential. The mechanical connections can loosen and corrode over time. This welds the cable and rod together. Very simple to use and sort of fun - like the Fourth of July!

 

[rockwithjason]

Go to home depot and rent a breaking hammer with a groung rod driver. You will drive the rod in about 3 minutes. If you go the sledge rout, pout about 1/2 gallon of water on the ground before you start and pour a splash every 20 or so hits. As for the hole in the foundation, I would call a core drilling outfit and see what they would charge you to cut the hole for you and then weigh that against renting the equipment at home depot to cut the hole yourself.

Those cadwelds are neat but they are very dangerous if not done properly. There must be absolutely no water in the mold when you fire the shot. That stuff burns at 4000degF.

 

[somky]

As others have said a sledge will work. It is fairly difficult.

However, if you get you hands on a rotary hammer drill to do the 1 1/2" hole use it to drive the ground rod also. Set it for hammer only. Chuck it up to the ground rod. The rotary hammer will bury the ground rod in less the 2 minutes with no effort on your part. Absolutely the easiest way to do it.

SomKy

 

[V-10 Killer]

Do you have poured concrete walls or block?
If it's block, why not just punch a 2" hole through one of the block cores with the sledgehammer. You'd need to have dug down (assuming crawlspace) to where it'll be coming in under the house anyway.

 

[markb1]

T-post driver first half sledge second half.

 

[Bevis]

getting ready to do the same. what size conduit do i need to run wire through for a 100a sub panel, approx 65 feet from main power??

 

[nova65ss]

getting ready to do the same. what size conduit do i need to run wire through for a 100a sub panel, approx 65 feet from main power??

I ran 3 "1 aluminum and 1 #4 in 2" and actually brought it down to 1 1/2 at the house but it was hard to work with. I would go at least 2" all the way if your box can support it.

 

[fastleft]

Thanks for all the great information!!

I had a great weekend so far... Friday I was talking to a friend and found out that he owns a rotary hammer with a 1 1/2 bit long enough to do what I need and a bit made to drive ground rods... thats free. Yesterday I got a great deal on the wire I needed. Today my neighbor told me he had a ditch witch.... 1 hour later the trench was done... free as well. Hopefully tomorrow I can get the conduit in place.

Thanks again!

 

[ng8264723]

Why do you need a grund rod for a sub panel?

 

[cw_racefan]

Why do you need a grund rod for a sub panel?

A sub panel in a detached structure requires it's own ground rod by code.

 

[Charles (in GA)]

Why do you need a grund rod for a sub panel?

Short explination, because NEC 250.32 requires it for separate buildings or structures with branch circuits supplied by feeders from another building or structure.

Its a safety thing, you don't want to be dependent on a ground wire all the way back to your service disconnect. The ground wire back to the main must be installed also, but you simply don't want to be dependent on it in this case.

Charles

 

[ng8264723]

Oh I see. I have a barn that is attached to my house via a el. The barn has a 100 amp subpanel with no ground rod. I guess it's okay since it's attached. The 100amp feed is around 100 feet long to the panel though.

 

[nova65ss]

Oh I see. I have a barn that is attached to my house via a el. The barn has a 100 amp subpanel with no ground rod. I guess it's okay since it's attached. The 100amp feed is around 100 feet long to the panel though.

Being attached and not attached is just a code thing. If you have a separate sub panel it still needs to have a ground rod, doesn't matter if it is attached or not.