What part of the code covers burglar alarm wiring and fire alarm wiring installations? what size ground wire should be used to ground a alarm panel? Is it OK to run the ground wire to the nearest cold water pipe or is it required to be run back to within 5ft of where the water pipe enters the building?

725.9 Class 1, Class 2, and Class 3 Circuit Grounding.
Class 1, Class 2, and Class 3 circuits and equipment shall be grounded in accordance with Article 250.

250 does not allow you to arbitrarily grab a water pipe. You should probably be going back to the service disconnect enclosure ground bus if you are looking for a "loop free" ground. That is the point where "star" grounding should originate.

Article 760 covers fire alarm systems and again steers you back to 250 RE grounding (760.9 2002 NEC).
Typically the grounding will originate in the panel serving the control panel and be routed with the branch circuit conductors feeding the panel. No different than a duplex receptacle.

Would anyone critique me if I said that the wire gage should be at least #14 AWG and that is should be either green or bare for it's entire length? See 250.120(A) and 250.119.

I think the #14 would be fine if fed with a 15A or smaller circuit. If it's a commercial application it would more than likely be fed with 20A and be required to be #12.

Here is another thought. I did some wiring today in a Notifier fire alarm system power supply and noticed that at the branch circuit terminal bar the connection point for the "ground" did not say ground it said earth. both on the term strip and on the directory inside the panel cover. I wonder if something like this has raised the question.

The alarm panel in question is typically used in residential dwellings and is not feed with line voltage.The panel is powered by a transformer that is pluged into a 120 volt plug remote from the panel itself. The panel is of steel construction and inside there is a terminal for a ground connection. What is the proper way to ground the alarm panel?

OOOhhhhhhh!
Your system is not required by the NEC to be grounded so the proper way to ground it is to ground it by what ever way the manufacturer recommends to ground it. I would imagine they are using the ground in this case to look for ground faults on the field wiring or to clear static off the case/board. The ones I have seen do in fact ask for a wire to cold water pipe....and as I remember the wire size is determined by conductor length. Your not dealing with life threatening voltage here, 12V maybe 16V off the transformer.

just reading the manufacters instructions for a burg/fire alarm panel I used to install. It says" Connect the control panel earth ground screw through a #16 AWG or larger wire to a cold metal water pipe or a buried ground rod. DO NOT use a gas pipe, plastic pipe, or AC Ground connections. This panel is fed with a 16.5 VAC transformer.It also says that this equipment should be installed in accordance with NFPA -72 national fire alarm code. Is there a difference in grounding requirements because it is considered under different jurisdiction?

trekkie
We must have posted at the same time.
NFPA 72 does not tell you how to ground the panel that part of the install will fall under 70. The reason they say to install per NFPA 72 ( IF the panel is used as part of a required Fire Alarm Control Panel.) is about where you put smoke detectors, heat detectors duct detectors, pull stations, strobes and horn/strobes. How the system is monitored an by whom. How much standby and alarm time is required with no A.C. power and how it is tested and maintained. ( This list just scratches the surface of NFPA 72 requirements.)

thanx for the reply's guy's...kentvw, soooo the cold water pipe is used for grounding in this situation.The telephone and catv systems do not have life threating voltage either but are required to be grounded (bonded) so they will have the same potential between systems in case there is lightning or accidential contact with power lines.

If there is any reference that tells the installer to install grounding per Article 250 of the NEC, we are pretty much limited to at least a #14 AWG- bare or green. I have never seen an instruction that said bond/ground to the nearest cold water pipe. I've been an inspector for 25 years and a contractor for 12 years prior to that. I am still learning so please fill me in.

the Gemini GEM_P3200 control panel/communicator instructions manual clearly spells out how they want the control panel to be grounded. min. size (for them anyway) is #16 AWG

Unfortunately many of these manufacturers are not familiar with proper grounding. The nearest cold water pipe can cause more problems than good, I have seen panels destroyed because of it during lightning storms.

The ground should be run in accordance with Art 250.

-Hal

Oh, let's open up a can of worms? I just think all of the opinions are great and why... I still stand by the fact that it is only a 12v system and offers no code noncompliance if the "ground" is connected to the water supply. Please give me a code article and not an opinion that says I am wrong.......( Must admit I do not like it either.)

I see a lot of total BS by electronics types who don't even understand how to protect their electronics and certainly don't have a clue about the NEC.
Again, refer to good old article 250!
If you drive another ground rod it SHALL be bonded to the ground electrode system.
There is no scenario where a "cold water pipe" is an acceptible ground for equipment.
There may be a piece of plastic in there somewhere.
In either above case (unbonded ground rod or "open" water pipe) your equipment will become the ground path that reconciles any ground shift difference making things worse than it would have been if you didn't "ground" it at all.
An article 250 ground will either be to ground it to the EGC in the circuit that supplies the equipment or to go to another point bonded to the building electrode.
In the computer biz they like going all the way back to the service disconnect so there is no intervening ground loop. I have never been convinced that ever fixed anything and I did it for 30 years.
You will be fine if you just go to the branch circuit EGC. It will certainly be code legal.

I am in for an education! So please tell me where it says in the code that a ground rod driven for only CATV or telephone systems needs to be bonded to the AC grounding system?

here's one
800.40(D) 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. Bonding together of all separate electrodes shall be permitted.
Exception: At mobile homes as covered in 800.41.
FPN No. 1:See 250.60 for use of air terminals (lightning rods).
FPN No. 2:Bonding together of all separate electrodes limits potential differences between them and between their associated wiring systems.

BTW FPN 2 is why the Telco or TV company should want to connect them all together.
"Ground" isn't zero volts and the actual voltage can vary quite a bit over a fairly small distance when you have a lightning strike. That difference can either be reconciled by heating up a #6 or by exploding a transistor ... your choice.
When we were fixing problems with blown LAN cards we were running fat bond wires along with them that tied the cases of the PCs together. Same concept. Give the shot a more attractive path. We also added ferrite beads to the signal cables to make that path less attractive but that is going beyond the scope of this thread.

In some areas consider the water pipe is the primary ground, the rod is secondary. (Due to soil conditions) It's a bit of a throw back to the days before PVC was acceptable for wide use in many areas of the country. Also not too long ago, ANY cold water pipe ANYWHERE was considered an acceptable ground. (not any more...) Recentley, we changed (locally?)to bonding gas lines at the nearest point past the meter. Point is things and attitudes toward the concept change....

Recently, during lunch watched a CATV contractor get chewed out by his boss for grounding his installation to a rod or water, instead of the main panel itself. ?????? (Didn't want to butt-in....)

shortcircuit, I think a simple jumper to a water (grounded), or equipment ground would be fine. This is an alarm panel, not a Service. The branch circuit is grounded right?

Now what is a "ferrite bead", and what purpose does it serve?

kentvw...I couldn't find anything in the code that restricts the connection of a ground wire to a water pipe for the fire alarm system I've described in my 2nd post.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.Section 1-5.5.5 of the 1999 NFPA 72 says that "All systems shall test free of grounds".The panel that I saw required a ground to be connected to the circuit board and didn't require grounding of the steel enclosure. Manufacturers instructions seem to be the rule here.
Looking in the code I could not find anything specific to grounding of fire alarm panels.Artical 760 covers fire alarm circuits except for 760.9 which sends us to artical 250. Then there is 250.112(A) (I) which says CIRCUITS shall be grounded where required by part II or part VIII of article 250.
An exsample of another low voltage system we install that the steel parts are not grounded is a simple chime system...chime and door buttons are of steel construction sometimes.
e57...250.20(A) again refers to "circuits" and not equipment. The branch circuit that the transformer is pluged into is grounded.

shortcircuit

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

Well we know Hbiss is the final word....
So please explain how that short circuit on the load side or ground fault on the load side will trip the OCPD protecting this panel?

Isn't the cold water pipe an AC ground connection(provided it's metallic and the service is using it as a GEC)?

steve

Isn't the cold water pipe an AC ground connection(provided it's metallic and the service is using it as a GEC)?

Yes if it's as you say but it's not code because a cold water pipe does not guarantee a ground back to the service.

...please explain how that short circuit on the load side or ground fault on the load side will trip the OCPD protecting this panel?

I'm assuming by "load side" you are refering to the wiring after the security, fire or other panel. If the panel is powered by an external transformer the panel, wiring and any devices connected to the wiring are floating- there is no ground reference because of the transformer.

In the not unlikely event that this wiring should become energized due to a cross with a class 1 circuit anyone coming in contact with any part of the system would be in danger. The condition would go undetected because no current would flow- and the panel, wiring and devices would be "hot" with reference to any grounded object.

The ground screw is meant to provide a return path to ground in this instance. If the wiring is such that enough current can flow the OCPD on the class 1 circuit will trip. At the very least fuses internal to the panel will blow or small gauge wiring will melt which in turn will disrupt operation of the system.

-Hal

Ok vote time:

A:To the Service.
B:To the EGC in the box serving it.
C:To the water line 5' from entering the building.
D:Any water line 15' away with #16 per instructions.
E:Not at all.

I choose "B"!

I almost flip-flopped, no still 'B'!

I have to go with "d" . I have an old '96 NEC. In it under grounding seperately derived grounded systems, it lists the nearest effectively grounded metal water pipe as grounding electrode to be used. Not sure when they deleted this phrase in the NEC, but it may explain where it came from. Apparently the engineers haven't gotten the update.

[This message has been edited by trekkie76 (edited 09-13-2004).]

But is this a separatly derived AC system?
All of the premisis wiring is 12V DC and in no way phisically connected to the ground.
I asked a honeywell tech what the ground was used for and was told it was only to protect the P.C. board from damage caused by arcs as well as surges coming off of the monitoring phone lines.

Will add that a note in an install manual makes the statement that if a grounded water line is not available then a 6' ground rod MUST be used

[This message has been edited by kentvw (edited 09-13-2004).]

the plug in trans. is 12 VAC. no connection to the nuetral, no direct electrical connection to the regular electrical system.By def. it is a seperately derived system.I have seen that same note in an FBI panel manual.

[This message has been edited by trekkie76 (edited 09-13-2004).]

Still do not think it is required to be grounded at all.
250.20(D) "Separatly derived systems, as covered in 250.20(A) or (B) shall be grounded as specified in 250.30"

250.20(A).."Alternating-current circuits of less than 50volts shallbe grounded under any of the following conditions:
(1) Where supplied by transformers, if the transformer supply system exceeds 150 volts to ground
(2)Where supplied by transformers, if the transformer supply system is ungrounded
(3) Where installed as overhead conductors outside of buildings

In this case the transformer supply is is 120 volts. My duplex feeding the transformer is grounded and I have no outside wiring.
So I am not required to ground the system.

HERE IS THE CATCH
250.20 ......Other circuits and systems shall be permitted to be grounded. If such systems are grounded, they SHALL comply with the applicable provisions of this article.

Taking the ground wire the nearest cold water pipe ain't gonna meet code.

I stand corrected! THANK YOU
What a great code question!

As trekkie pointed out this did change between 99 and the 02 code. 99 said nearest available effectively grounded water pipe and the 02 changed to within 5' of entrance.

[This message has been edited by kentvw (edited 09-13-2004).]

I asked a honeywell tech what the ground was used for and was told it was only to protect the P.C. board from damage caused by arcs as well as surges coming off of the monitoring phone lines.

Don't know about the arcs but he brings up a point I touched on in my first post. If the panel is connected to a telephone line there are surge protectors from each side to ground to protect the circuitry. Many panels have surge protection on the terminals connecting to the premises wiring also particulary if there is a possibility that they may be run outside.

Another reason for a proper ground.

-Hal


[This message has been edited by hbiss (edited 09-13-2004).]

"What a great code question!"
True, very true! I still say to the EGC of the circuit, as it is a guaranteed ground/bond to water, service, and phone. Be it code or not.(my opinion)
Not to mention a lot easier than the alternatives... Except not doing it at all.

Well...tuff question I guess.Does the 2002 NEC allow a cold water pipe(beyond 5ft from the point of entrance to the building) for connection of a grounding conductor?
The definition of equipment grounding conductor is "The conductor used to connect non-current-carrying metal parts of equipment,raceways, and other enclosures to the system grounded conductor ,the grounding electrode conductor, or both, at the service equipment or at the source of a seperately derived system"
The wording "at the service equipment" or "at the source of a seperately derived system" implies that equipment grounding conductors must be run to the service equipment.
250.130 instructs on how the connection shall be made.
My answer is NO the 2002 Nec doesn't allow the connection to a metal water pipe beyond 5ft of the point of entrance of that pipe to the building.
The instruction with the alarm panel must be outdated.

shortcircuit