Thread: single grounding rod

ICC practice exam question:

If the system is grounded with a single ground rod, what is the maximum size copper required for the grounding electrode conductor regardless of the size of the electrical service?

a) #8
b) #6
c) #4
d) 3/0

I say #6 , but the answer is #4.

thanks as always for your help!

Similar Threads:

• Single Wall Window Installation
• SIngle wall?
• Metal conduit grounding
• Who needs 6" of clearance for single wall
• Galvanizing Flaking Off Single Vent

Originally Posted by Wendell Swedberg

ICC practice exam question:

If the system is grounded with a single ground rod, what is the maximum size copper required for the grounding electrode conductor regardless of the size of the electrical service?

a) #8
b) #6
c) #4
d) 3/0

I say #6 , but the answer is #4.

thanks as always for your help!

You mean minimum size, right?

no, the question does say maximum.....

Originally Posted by John Arnold

You mean minimum size, right?

John,

Maximum "required" in no way implies "maximum allowed".

Wendell,

Reading Table E3503.1 and notes 'a' and 'd', it does appear that 6 AWG copper is the "maximum size copper required" when the "system is grounded with a single ground rod".

What confuses things is that note 'd' states "Where the sole grounding electrode system is a ground or pipe as covered in Section E3508.2 ... "

And E3508.2 states: (which does not apply to "the sole grounding electrode system is a ground or pipe" as no bonding jumper is needed)

- E3508.2 Bonding jumper.

The bonding jumper(s) used to connect the grounding electrodes together to form the grounding electrode system shall be installed in accordance with Sections E3510.2, and E3510.3, shall be sized in accordance with Section E3503.4, and shall be connected in the manner specified in Section E3511.1.

This jumps from 'a grounding electrode conductor to a single ground rod' (singular) to 'a bonding jumper used to connect grounding electrodes together' (plural).

I don't see how that applies?????

That also refers you back to E3503.4:

- E3503.4 Grounding electrode conductor size.

The grounding electrode conductors shall be sized based on the size of the service entrance conductors as required in Table E3503.1.

Which is back to where we started.

It's almost like they did not mean to use the word "copper" in there, in which case (changing the word "copper" to "conductor")

'If the system is grounded with a single ground rod, what is the maximum size conductor required for the grounding electrode conductor regardless of the size of the electrical service?'

In that case, the answer would be #4.

Maybe I need to read that through again in the morning?

thanks, Jerry....there are just soooo many errors in the ICC practice exam questions and workbooks.....but they are still usefull materials , excericises to go through.