TELECOM Digest OnLine - Sorted: Re: Supplemental Grounding Electrodes

Re: Supplemental Grounding Electrodes

Paul Coxwell (paulcoxwell@tiscali.co.uk)
Mon, 04 Jul 2005 12:25:25 +0100

> Article 250.54 of the NEC says local supplemental grounding
> electrodes (such as the one for phone service) must be bonded to
> the primary electrode. Where does the NEC apply? According to
> what the telco man admitted seven years ago, I assume our county
> code says the same thing.

As I understand it the NEC applies in any state, county or local
jurisdiction which has adopted it -- which is most. There may be
local codes which explicitly amend any NEC requirement though.

Which edition of the NEC are you looking at? In the 2002 edition
article 250.54 relates to supplementary electrodes which MAY be
bonded, not MUST. 250.58 does seem to correspond with 250.54 in
earlier editions though, so that could be the section you are looking
at.

Chapter 8 of the NEC also relates specifically to communication systems.
Article 800.40(D) in the 2002 edition states:

QUOTE
Bonding of Electrodes. A bonding jumper not smaller than 6 AWG copper
or equivalent shall be connected between the communications grounding
electrode and power grounding electrode system at the building or
structure served where separate electrodes are used.
/QUOTE

> Is this a recent addition to the NEC?

No. I don't know how far back the requirement goes, but the 1971 NEC
says much the same thing in article 800-31(b)(7):

QUOTE
Bonding of Electrodes. A bond not smaller than No. 6 copper or
equivalent shall be placed between the communication and power grounding
electrodes where the requirements of (5) above result in the use of
separate electrodes.
/QUOTE

Disclaimer: Being British I'm just an outside observer to the NEC. I
could post your query in a Stateside electrical forum where we have
some NEC experts though, if you wish.

- Paul

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