250.53.G and 250.56

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Chamuit

Chamuit

Grumpy Old Man
Location
Texas
Occupation
Electrician
If you installed 2 ground rods horizontally in a 2.5 ft deep trench, would they need to be 6ft apart or could the be end to end?

A. <----grnd rod----><--6ft--><----grnd rod---->

B. <----grnd rod----><----grnd rod---->

I'm curious as to what the inspectors here think.

Friday, an inspector allowed "B" because I had "met the intent of the Code." Of which, I was greatful because it took two days with a jack hammer just to dig the 16 ft x 30" long trench in the granite bedrock.
 
Chamuit said:
If you installed 2 ground rods horizontally in a 2.5 ft deep trench, would they need to be 6ft apart or could the be end to end?

A. <----grnd rod----><--6ft--><----grnd rod---->

B. <----grnd rod----><----grnd rod---->

I'm curious as to what the inspectors here think.

Friday, an inspector allowed "B" because I had "met the intent of the Code." Of which, I was greatful because it took two days with a jack hammer just to dig the 16 ft x 30" long trench in the granite bedrock.
Click to expand...



That's a really interesting question. I believe he sympathised with you and let this slide. IMO, even in those rough terrains, horizontal, the 6' rule still applies
 
Chamuit said:
it took two days with a jack hammer just to dig the 16 ft x 30" long trench in the granite bedrock.
Click to expand...

Although required, one has to think that ground rods installed in those conditions can't provide much of a benefit should they be called upon.
 
Chamuit said:
Of which, I was greatful because it took two days with a jack hammer just to dig the 16 ft x 30" long trench in the granite bedrock.
Click to expand...

That's a pity esp. since ground rods are almost worthless. I do believe the intent is to be 6 feet apart from the end of the rod. The code does not say when the rods are vertical it needs 6', but rather they need a minimum of 6'. Your installation doesn't get it.

What did they dig the footings with or is this remo work?
 
Dennis Alwon said:
That's a pity esp. since ground rods are almost worthless. I do believe the intent is to be 6 feet apart from the end of the rod. The code does not say when the rods are vertical it needs 6', but rather they need a minimum of 6'. Your installation doesn't get it.

What did they dig the footings with or is this remo work?
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Existing house built in 1960 on the side of a mountain. The existing ground is the 1" water line (copper) about 6" deep (in the imported top soil) that runs around most of the house. Doing a service change.

Here's a picture of the pole that the POCO is going to replace. Shows the rock we had to dig through.

April252010077.jpg
 
Chamuit said:
...it took two days with a jack hammer just to dig the 16 ft x 30" long trench in the granite bedrock.
Click to expand...
Next time :roll: consider using plate electrodes. Well actually, there shouldn't be any considering to it ;) Each has to expose 2ft? [250.52(A)(7)], which is essentially a 1ft? plate. So two 16" square holes with 6' of separation plus trenching for GEC is a lot less than 16" x 30' [36' ???].
 
According to the "Electrical Inspection Manual" by Williams and Sargent:

A greater spacing may provide better efficiency in establishing a good connection to the earth. A common recommendation or rule of thumb is to drive multiple electrodes as far apart as they are long, but this is not a code requirement.

He must of saw the Bedrock and gave you a break.:grin:
 
erickench said:
According to the "Electrical Inspection Manual" by Williams and Sargent:

A greater spacing may provide better efficiency in establishing a good connection to the earth. A common recommendation or rule of thumb is to drive multiple electrodes as far apart as they are long, but this is not a code requirement.

He must of saw the Bedrock and gave you a break.:grin:
Click to expand...

Though that quote likely refers to rods in a vertical position. In the OP's situation,vertically speaking, they are 8' wide and 1/2" long, so they may meet the proposed 'rule of thumb" after all :cool: :grin:.
 
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