grounding

[SHAUN RICE]

the dept of community affairs in new jersey says the only grounding electrode required for a single family dwelling is a#4 cu concrete encased electrode. i have 2 steel i-beams which i bonded with # 4 cu 1.5 years ago . The service passed inspection and has been energized scince. the service size is 400 amp 120 240 single phase .AT final inspection the temp inspector failed the grounding and wants the 100 foot #4 increased to 1/0cu to the 2 i-beams citing 250.66. the well is plastic and the interior water piping is plastic does anyone have any guidance?

 

[raider1]

Welcome to the forum.

Do the steel I-beams meet the requirements in 250.52(A)(2) to be used as a grounding electrode? By this I mean are the I-beams connected to the earth by one of the 4 methods listed in 250.52(A)(2).

If the I-beams meet the requirements of building steel to be used as a grounding electrode, then the grounding electrode conductor that is to be connected to this would need to be sized from Table 250.66 based on the largest ungrounded service entrance conductor.

If you have ran 500 Kcmil copper conductors for your 400 amp service, then according to 250.66 you would need to have a 1/0 copper GEC. Again this is if the I-beams you have qualify as a grounding electrode.

Chris

 

[augie47]

the dept of community affairs in new jersey says the only grounding electrode required for a single family dwelling is a#4 cu concrete encased electrode....................

No doubt that statement is true to a point ..it may be the only electrode required, BUT, 250.50 states:All grounding electrodes as described in 250.52(A)(1) through (A)(7) that are present at each building or structure served shall be bonded together to form the grounding electrode system
So, as Chris states, if the beams qualify as an electrode they must be used also.

 

[gndrod]

I beam electrode?

I beam electrode?

the dept of community affairs in new jersey says the only grounding electrode required for a single family dwelling is a#4 cu concrete encased electrode. i have 2 steel i-beams which i bonded with # 4 cu 1.5 years ago . The service passed inspection and has been energized scince. the service size is 400 amp 120 240 single phase .AT final inspection the temp inspector failed the grounding and wants the 100 foot #4 increased to 1/0cu to the 2 i-beams citing 250.66. the well is plastic and the interior water piping is plastic does anyone have any guidance?

Hi Shaun,

First up, welcome to MH's forum. Second, if you could describe the I-Beams and if they are encased by length in concrete or direct buried? If they are not...then they are not electrodes and only need bonding if they are prone to be potentially energized. If they are not prone, then bonding is not required either. rbj

 

[RICK NAPIER]

The NJ DCA would accept the steel if it met 250.52(A)(2) which residential steel usually does not. Also they would require 250.50 be met. In my experience the NJ DCA follows the generally accepted understanding of article 250 of the NEC.

 

[gndrod]

Hi Shaun,

First up, welcome to MH's forum. Second, if you could describe the I-Beams and if they are encased by length in concrete or direct buried? If they are not...then they are not electrodes and only need bonding if they are prone to be potentially energized. If they are not prone, then bonding is not required either. rbj

250.4(A)(4) Electrically conductive materials and Other Equipment.
Normally non-current-carrying electrically conductive materials that are likely to become energized shall be connected together.....etc.

 

[SHAUN RICE]

thanks for responding the i-beams are exposed in the basement the dca i spoke to yesterday told me in no uncertain terms that a#4cu was all that is needed.i do not understand why #4 to the footing is ok when the presence of a cu water service would require 1/0.scince the advent of plastic water piping for well & interior piping there seems to be alot of confusion over grounding .the dca said i do not even need groun d rods

 

[SHAUN RICE]

if there were no i-beams what grounding would be needed? why are ground wires not increased in size over 3/0.does not a 4000 amp service need a larger conductor than a 1000? it goes against all my experience to use a #4cu concrete encased electrode for a400 amp service but that is what i am getting from state. i spoke to two other inspectors in bergen county they say they were told the same thing. and remember this service was passed already .

 

[raider1]

if there were no i-beams what grounding would be needed?

250.50 requires all grounding electrodes that are present to be bonded together to form the grounding electrode system. If a concrete encased electrode, metal water pipe, or building steel is not present than you need to install a man made electrode.

I have a concern that the I-beams actually meet the requirements for use as a grounding electrode. Are the I-beams connected to the earth?

it goes against all my experience to use a #4cu concrete encased electrode for a400 amp service but that is what i am getting from state.

Correct, a concrete encased electrode need not be larger than a #4 copper regardless of the service size.

Chris

 

[suemarkp]

if there were no i-beams what grounding would be needed? why are ground wires not increased in size over 3/0.does not a 4000 amp service need a larger conductor than a 1000? it goes against all my experience to use a #4cu concrete encased electrode for a400 amp service but that is what i am getting from state. i spoke to two other inspectors in bergen county they say they were told the same thing. and remember this service was passed already .

Since it sounds like your I beams aren't really ground electrodes, you need something else (but verify with the electrical inspector whether these beams are or are not a ground electrode -- if they are then you need to upsize to 1/0 copper). Two ground rods is what you usually install in that case if you have no concrete encased electrode installed. And a ground rod only needs #6 like a concrete encased electrode only needs #4. Don't know why, and you can exceed those sizes if you want, but that's the rules. Similarly, if you had any metal piping, whether it was a ground electrode or not, you'd have to run 1/0 copper to it just for bonding purposes. No one says all the rules in article 250 make sense. You just have to know what they say.

 

[Pierre C Belarge]

As has already been mentioned a few times, not all instances where steel is used would fit the requirement of 250.52(A)(2).

This picture is an example of where I would say the steel is not an electrode as per 250.52(A)(2). "The metal frame of the building or structure..."