Grond rod question

[electricmanscott]

Installing a service in an old barn today. Could not get the ground rods in. (bedrock?) Instead I laid them in the trench that the service is run in. It is about three feet deep. I used three rods, each one six feet from the other. Reading through the handbook I am not to clear on this exact situation. Appreciate all thoughts.

 

[tom baker]

Re: Grond rod question

See section 250.53(G). It describes the acceptable methods for installing rod electrodes.

 

[electricmanscott]

Re: Grond rod question

Tom, I read through it all and the handbook has good pictures. I am unclear as to the spacing when the rods are not driven but instead laid in a trench. NEC doesn't seem to specify anything on multiple rods installed this way.

 

[gserve]

Re: Grond rod question

You only need 2 rods and they are laid in the trench a min. of 6' apart horizontally

 

[tom baker]

Re: Grond rod question

Yes GS is correct, 6 ft spacing is required. So you will need a about 25 feet of ditch.

 

[spyder]

Re: Grond rod question

Use a ground ring instead. Make them dig you a trench around the entire building, lay #2 bare in the trench and call it a day. Piece of cake. Just kidding. Has anyone on here ever used a ground ring for a builing other than a telephone booth?

 

[iwire]

Re: Grond rod question

I am doing a ground ring now that will use 700'+ of 4/0 bare, all due to job specs.

[ March 30, 2003, 11:50 AM: Message edited by: iwire ]

 

[svaurez]

Re: Grond rod question

A ground ring is only required to be 20' in length.How can that possibly "encircle" the building?

 

[dereckbc]

Re: Grond rod question

SVAUREZ, a ground ring minimum length is 20 feet, not maximum.

Spyder, I use ground rings all the time, especially if lightning protection is called for.

 

[iwire]

Re: Grond rod question

Dereck nailed it svaurez, the one I am doing is tied into bulding steel and lightning protection.

The 700' I am adding is just for an addition, the total length will be around 2000' - 2500'.

 

[hornetd]

Re: Grond rod question

Originally posted by electricmanscott:
Installing a service in an old barn today. Could not get the ground rods in. (bedrock?) Instead I laid them in the trench that the service is run in. It is about three feet deep. I used three rods, each one six feet from the other. Reading through the handbook I am not to clear on this exact situation. Appreciate all thoughts.

How long is the trench? If there are not still stock there you could run a pseudo ground ring by using number two as your grounding electrode conductor through the ground clamps on your rods and clean back to the service equipment via the trench. This would cause the two buildings to have a common grounding electrode system which is a great way of avoiding damage from surges.

If there is still dairy stock present then use an insulated GEC and cover the rods with diatumacious earth for six inches followed by six inches of clay to protect it from the amimal waste which would corode it away to nothing in only a few years. You should also cover the clamps with conductive anti oxidase paste and then shrink tubing.

Is this the same old dairy barn someone was talking about were the new feeder will supply a water pump? If you can run a grounding electrode conductor to the metal well casing you will have the best electrode a rural service can have.
--
Tom

[ March 30, 2003, 11:14 PM: Message edited by: hornetd ]

 

[electricmanscott]

Re: Grond rod question

No cows in this barn anymore! Inspected today, all set! Thanks for input.