Grounding Electrode Conductor Taps

[avr]

I am installing a 5 gang meter socket that will feed 3 100 amp panels for 3 apartments, a 100 amp panel for a commercial rental area and a 200 amp panel for a second commercial rental area. I want to run a 1/o awg copper to the water bond and tap off this to each disconnect with #6awg copper for each 100 amp disconnect and a #4awg copper for the 200 amp per 250.30(A)(3).
My question is: Is there a way to connect the taps with out a crimp or weld? Does a split bolt with tape on it meet the requirment of an irreversible compression connector? Can I also bring just one #6 awg copper conductor from the ground rods to the first main disconnect outside the building instead of bringing a conductor from each disconnect to the ground rods?(All 5 main disconnects are ganged together and bonded together.)

 

[bphgravity]

Re: Grounding Electrode Conductor Taps

I believe you are in the wrong section. 250.30 applies to separately dervived systems. I think you need to look at 250.64(D).

The grounding electrode conductor sized will be based on the size of your service entrance conductors per 250.66, and each tap will be sized based on the size of the ungrounded conductor serving each disconnect.

I do not believe you are required to use am irreversible compression type connector or weld for this application. A split bolt with or without tap should be fine, see section 250.70

I don't think your last question would be permitted.

 

[gndrod]

Re: Grounding Electrode Conductor Taps

What point of construction is this project at? A good choice for a grounding system would be to use a Ufer ground and save the cost of all those ground rods. If foundation is poured, then I think the next choice (if all 5 disconnects are ganged and bonded together) may be to install one set of staked electrodes for the system ganged meter center and then run a four wire off each meter main disconnect to the separate panelboards if the building is one structure.If this is a remod (or in the Chicago area) then disregard all of the above.

 

[iwire]

Re: Grounding Electrode Conductor Taps

Can I also bring just one #6 awg copper conductor from the ground rods to the first main disconnect outside the building instead of bringing a conductor from each disconnect to the ground rods?(All 5 main disconnects are ganged together and bonded together.)

Is there one main disconnect outside?

[ October 23, 2004, 05:54 PM: Message edited by: iwire ]

 

[avr]

Re: Grounding Electrode Conductor Taps

* Picture a 5 gang meter socket with nipples out the bottom to 5 seperate main disconnects. 4-100 amp and 1-200 amp. Then 5 seperate sub panels in different parts of the building.

* If I have to, I will run a #6 from each disconnect to the 2 ground rods. I will not drop 2 for each disconnect.

* The project is a remodel in Michigan. It is just in the plan phase. I am useing the meter socket that is already there and upgrading three 60 amp disconnects to 100 and adding sub panels in the apartments. Owner is adding electric heat in all apartments plus updating all electrical in building.

* I will look up the section you recomended. I didn't pay alot of atention to what code section I was in when I referanced the code I did. Thank you. I did know that it said that I had to have a tap of irreversable means and I turned to the first spot I saw that.

 

[iwire]

Re: Grounding Electrode Conductor Taps

I would run one GEC and make taps as shown in this handbook graphic.

 

[avr]

Re: Grounding Electrode Conductor Taps

(Iwire)
So you are suggesting that I do the same I am plannining to do for the water bond for the ground rods? That would be to run a 1/o awg copper to the rods (so the correct potential is there if there was a "short" involving more than just any one set of service conductors) and tap off this with #6 awg to each disconnect. If so, what type of connectors for the tap can be used(same as my first question)?

 

[avr]

Re: Grounding Electrode Conductor Taps

OK, I can use just split bolts but can I run just a #6 to the ground rods and just daisy chain the #6 between each disconnect and then to the ground rods?

 

[suemarkp]

Re: Grounding Electrode Conductor Taps

Doesn't 250.142 allow him to use the grounded neutral conductor to serve as the grounding conductor too? In that case, just running a ground from one panel (or a busway) would be sufficient as long as a grounded conductor is run to each panel. There is certainly nothing wrong with the picture posted showing a GEC coming out of each panel, and is probably the "best practice", but I don't believe that level of grounding redundancy is required.

 

[pierre]

Re: Grounding Electrode Conductor Taps

250.53(D)(2)
Permits you to take a 6AWG from the ground rod(s) back to the GEC and connect it to the GEC. You are not required to install it to each service disconnect, if you are installing a GEC and using Grounding Electrode Conductor Taps 250.64(D) to each service disconnect.

Pierre

 

[hurk27]

Re: Grounding Electrode Conductor Taps

I agree that only one is needed, as with a muti-gain meter pack all the grounded conductors will be bonded together in the meter pack. But the GEC to a rod type electrode will still only have to be a #6 AWG if it is the sole connection to the rod, Ufer will have to be a #4, and a water pipe electrode will have to be sized from table 250.66