ECN Forum Forums Code Related Discussion NEC & other Code issues alarm panel grounding

Point me to a place in article 250 that says a water pipe is an acceptible equipment grounding path.

A ferrite bead makes a choke out of a signal cable that will provide an impedance to common mode transients. The impedance on signal itself will cancel in the ferrite since the out and in follow the same path in opposite directions. That is the heavy thing on a printer cable.

The exception immediately following 250.52A(1).

And, before the wide PVC, much to the dismay of those old-school plumbers, (and many electricians too.)a ground wasconsidered any cold water anywhere.
For instance the electrical service of my home is grounded to the 1/2" hose bib at the furthest point from the waters entry to the building. When it was done, that was acceptable. When I do the service over again, that will change! As do codes change...

Many of the burgler alarm guys here done ground at all! The only external metal part in the whole system is the can its in, after a protected and list class 2 LV transformer, they probhably dont feel they need to... I'm not sure if it's an article 250 issue at all really. So I would assume manufacture instuctions on this unit may surfice.

That is why we're discussing this right?

Thanks for the ferrite bead thing.



[This message has been edited by e57 (edited 09-09-2004).]

(posted for kentvw) See Instructions >> here

e57

That exception does allows making the GEC connection to the metal water pipe at distances greater than 5' from the point of entrance.

I do not see how it applies in the least to the question in this thread.

I agree with Greg no grounding connections are to be made to a water pipe further than 5' from the point of entrance.

ok shoot this one full of holes.
250-130(B), methods of equipment grounding for ungrounded systems. It says the EGC shall be made by bonding it to the grounding electrode conductor. Now, looking at the def. of Grounding electrode conductor, the last part says(paraphrasing) the condutor used the connect the EGC to grounding electrode at each service or at the SOURCE of a seperately derived system. So, I interpret that to mean the grounding electrode, or that part of the system near the Burg panel. and the plug -in transformer, which is the ungrounded seperately derived system.

[This message has been edited by trekkie76 (edited 09-09-2004).]

iwire,
gfretwell asked, "Point me to a place in article 250 that says a water pipe is an acceptible equipment grounding path."

I realize it's a long way off, but that did sound like a water pipe used as a grounding path?(And no, I wasn't trying to pick a bone, so to speak.)But like I said, before historicaly, and not too long ago, until it changed, and in the many existing installations out there, a cold water pipe has been considered a ground path. Maybe the instructions posted on the link above, haven't caught up to current code. Or maybe, I'm starting to think, that the installation of this ground is outside of the NEC all together???? (Although note 6 on that diagram says it is.) Becomes part of listed equipment past the plug in transformer?????

Anyway, there seems to be some disagreement as to the answer to shortciruit's original questions. As the Code isn't clear enough to convince 8 well qualified persons here on the absolute correct answer to this. We might need to vote on it, if we could figure out what to vote for...

I still stand by the fact that it is only a 12v system... I think I must agree with what you said in your 3rd post, that the ground is to clear any static off the board or to look for ground faults on field wiring.

The fact that it is 12v or even no volts has nothing to do with it nor does "static on the board" which is ridiculous.

The ground is necessary because there is premises wiring and devices connected to the system. Without a ground this wiring and consequently anything connected to it could become energized and not trip the OCPD.

Nothing new here- this is the same reason we bond water piping, building steel etc. The same rules apply.

-Hal

You are talking about an article that refers to bonding the electrode system. I specifically said "equipment grounding path" which is what we are talking about.
Why don't you just run a wire over to the EGC in the box feeding the transformer and be undisputably legal?

If the manufacturer sent this product to UL for listing, wouldn't they pick up on the grounding issues?? the Instructions MUST go with the product.

Good question. I'm not sure if the testing labs look at the instructions at all.

-Hal