ECN Forum Forums General Topics of the Trade General Discussion Area Lost Cold Water Ground

Reno:
Yes, 250 is confusing, no doubt. Mike has some good references. Over the years, wacky EE layouts/specs drove me (EC) and the inspectors up many a wall.

One memorable job consisted of a 20' ground electrode augered into mother earth, and backfilled with 'Montana Clay'. It was a 2" diameter heavy wall copper pipe, filled with some exotic salts' (Thinking 'Lyncole') 4/0 tail, cadwelded to more 4/0, then to a grd buss, cadwelded to a 1/4" copper plate. Plate covered the floor (wall to wall) of a clean room cell for some really deep electronics tool.

The inspector came in.....stared....shook his head....laughed....and wrote a red sticker! He had no clue why, but failed it on 'principal'. Long story short...plans were approved as installed, he came back...I explained...he laughed.. I showed him where the 'system' was bonded to the bldg steel, got a white sticker.

Lets see if anyone jumps in

Got to head home, may be back later

I spoke to an inspector friend of mine and he sugested a triad ground? Three 10' rods 15' apart connected together in a loop. Says the power companies use this to ground there pad mount tranfomers. Tesla, I agree with you 100% that was my reason for the post. I also agree your design on the ufeer would be the best. I would have to hand dig all said work at this point. As well as its 75' to the nearest curb to get concrete in. The whole thing is new shrubs and trees. What do you think of this above mentioned setup?

Ob

75' is brutal.

You might consider lapping the ground ring back and forth and somehow shoe-horning it into a spot closer to the Service.

There are drilling companies that might punch you a vertical ground ring/Ufer. I've heard tell of electricians getting away with a 'plug' Ufer wherein the GEC is wound down into a 24" site pole bore and then encased in concrete when the 'soil' conditions = granite.

Can you slip this project up against the old footings?
Total encasement then might be accepted by the AHJ.

Get a concrete pump. It is about $100 around here, probably cheaper if you shop around.
I also wondered about just trenching near the footer, drop in steel on chairs connected to the GEC and backfill with concrete to get a few inches of cover then continue filling with dirt. It sure sounds like a Ufer to me.

Personally I think the best Ufer in the world is an inground concrete swimming pool, particularly if it is into the ground water.

This is a 200yr old building. The footers are 3-1/2' of stone set with lime and sand. There has been some repointing done over the years thats it. We try and stay away from them as to not disturb them. The school does not have deep pockets(who does these days). I m going to talk to the local AHJ today and see what his thoughts are.

Ob