why ground an alarm panel.

As Mike has correctly noted, the term "safety ground" does not exist in the code. Other expressions such as bonding and ground are used. Well, which grounding? Grounding for earthing or grounding to breaker box neutral bar? You are expected to know which ground is discussed. IOW I have made is simpler for the layman. I have renamed what the various codes call for by using more easily understood terms such as "safety ground". I have referenced overall concepts in various codes into 'easier to grasp' terms - "human safety" and "transistor safety".

Numerous codes apply including UL, NEC, and maybe some from your utility. However all those codes come down to one fundamental point - a point more important than codes - a point based upon the purpose of all those codes:

Furthermore, that c> Would you please cite a code reference for this? Please keep in

your alarm panel?

have to do with grounding at the service disconnect? I realize that Qualified and Licensed Electricians SHOULD be the only ones opening panel boards and wiring into them, But who says "YOU HAVE TO CONNECT TO THE GROUND ROD?"

connect to the Grounding electrode CONDUCTOR?

not for panel boxes by themselves

BONDING is to quickly and safely conduct fault currents and reduce dangerous touch potential voltages GROUNDING is for conducting lightning and hi potential voltages to earth.

conductor to satisfy the requirements?

As posted earlier, the cold water pipe is no longer sufficient as ground. Copper wire to water pipe is for 'bonding' - to remove stray or dangerous currents from the pipe. NEC describes water pipe only as supplemental earthing. NEC lists what can be the only earthing electrode - water pipe is not in that list.

Other ground wires such as across 'cold to hot' at hot water heater, across water meter, etc are for 'human safety'. House must be wired so that a plumber can break any pipe connection and not affect electrical conductivity - human not endangered by electrical shock. This is a major change since the 1980s when water pipes were acceptable for grounding.

Furthermore, there exists no practicable way to measure or test for proper grounds. One can test for missing grounds, but one cannot test for sufficient grounds. Essential connections for human safety must be installed so as to be inspected. Inspection being necessary to verify properly installed grounds. Codes sometimes are not clear or specific about this. But again, this concept should be intuitively obvious - the purpose being human safety.

Code does not demand two ground rods placed 6 feet apart. But since 'few to no one' has equipment to meet code requirements, then many will assume earthing is insufficient and install the second rod.

Reasons for panel directly connected to earthing electrode is due to an electrical concept called impedance. Things that create too much impedance include splicing, sharp wire bends, running wire inside metallic conduit, lead solder joints, etc. 'Human safety' requires low resistance grounding. 'Transistor safety' requires low impedance grounding.

BTW, if a wire is longer, then increasing wire gauge does little to reduce wire 'impedance'. Wire impedance is defined more by wire length and less by wire diameter. Notice how this differs from another concept - wire 'resistance'. Something wired with a low resistance connection may not also be a low impedance connection. Routing of that wire can even make a significant difference for 'transistor safety'.

Aga> FYI - A good electrical service grounding system has a cold water

You haven't answered my question.

Please cite an NEC code reference that requires grounding of an enclosure that only contains Class 2 or power-limited fire alarm circuits. I don't give a damn what you think is "intuitively obvious." Cite a code reference to support your position!

- badenov

I'm not sure who may have anyone died but check the NEC and you'll find that what I've been saying is correct. The tone of my previous comment in this thread was in response to Bob Worthless' flame -- not directed at you.

I was replying to Bob Worthless.

Your question was answered accurately. Please read before posting:

If you need a specific code, then visit UL. Meanwhile with minimal technical knowledge, that point is well understood. If the appliance directly connected to AC mains has exposed metal, then it must have a safety ground. All those other codes conspire to demand that exposed conductive material on an appliance connect to the building's safety ground.

Need I also cite the specific NEC requirements that connect that third prong to building's safety ground? If I do, then you either have no business wiring anything electrical, or you only want to argue. If you don't know of NEC code that connects safety ground prong to building's safety ground, then you have no business wiring electrical items.

Meanwhile, a whole chapter from the NEC is called Article

250. I am not going to quote the so many relevant sentences for obvious reasons.

An electrically conductive surface on an AC appliance must have a connection to the building's safety ground system. An exception to safety grounds was once hyped with a sales expression, "Double Insulated". A term requiring minimal electrical knowledge of those various requirements that otherwise required a direct connection to the building's safety ground.

If an appliance c> You haven't answered my question.

Where did Bob start flaming you in this thread, exactly?? Was it perhaps *after* you posted the ludicrous suggestion that he can't install or service a commercial fire alarm system in Florida (where he's actually licensed and bonded)??

You said " Need I also cite the specific NEC requirements that connect that third prong to building's safety ground? " I think that was what he was looking for. Nomen said, "Would you please cite a code reference for this?"

You said "that third prong" but the standard non-X10 transformer that Ademco ships with has two screw terminals, neither of which connect to the ground prong.

You said " If an appliance connects directly to AC power, then it must have a safety ground. " but the typical alarm panel connects through a 'wall wart' AC transformer, not directly to AC power.

You said "you apparently do not understand" You are correct, I do not understand, and it looks like others do not as well. Hence the interest in seeing specific code references.

Thanks, I am learning a lot through all this.

Since you still have not provided an NEC reference requiring grounding of enclosures containing only Class 2 circuits, I must assume that either (a) you do not own a copy of the NEC, or (b) you cannot find an NEC section that supports your position.

Now, you appear to claim that UL requires grounding of such enclosures. All right, the relevant UL standards for alarm control panels include UL

1610, UL 609, UL 864, and UL 365. Please cite a paragraph from any of these standards that requires grounding of enclosures containing only Class= 2 circuits. I have copies of these standards...do you?

As to =91maybe some from your utility,=92 I haven=92t the slightest idea wh= at you are talking about. Do you?

Alarm control panels are not cord-connected devices. They don=92t have a cord, much less a third prong. Perhaps you have never seen an alarm control panel. That might explain your comments.

- badenov

Wall wart creates an exception because the panel is no longer directly connected to AC electric. The primary reason for doing this? Alarm panel no longer need be submitted to UL for expensive 'human safety' testing. Since the alarm panel is not longer directly connected, then it's exposed metal parts (technically) need not be safety grounded. Meanwhile, good practice dictates that the safety ground be connected anyway. This for human safety. And this also for reasons provided by Robert Bass.

Appreciate why so many appliances such as pr> You said " Need I also cite the specific NEC requirements that connect

Sorry Robert, I got a little hot under the collar, but no damage done. I assumed it was directed my way.

was directed my way.

No problem. Your questions were reasonable. Hope my answers helped clarify things a bit. W Tom alsdo has a good handle on the subject, as do Stevens and Badenov.

Regards, Robert L Bass

......and you had the gall to criticize my spelling

has a good handle on the subject, as

Ademco manuals clearly indicate that grounding is not required.

-G

What is legally required verses what is technically superior or recommended are two different things. It is also not required to brake long before the red traffic light. Does that mean you routinely race up to every red light, then apply brakes at the last minute? Its not illegal to do so. But better drivers brake long before they are "required" to brake.

No required building code demands lightning protection. UL, NEC, etc all make no consideration for transistor safety. Those codes only address human safety issues. An earthing connection, as described by Robert Bass, is for transistor safety. Something installed beyond what is required. We still build homes as if the transistor did not exist; still have no codes for transistor safety.

Meanwhile, cold water pipe is no longer acceptable for grounding. That is a post 1990 code change. Furthermore, it would not make a good earthing connection for other electrical reasons.

AC electric receptacle provides a safety ground; but is not an earth ground. This for electrical reas> Ademco manuals clearly indicate that grounding is not required.

Absolutely. In this case the two are the same. In my opinion, NOT grounding a panel is "technically superior", it's also not required by law.

That saves the brake system wear and tear, yes, grounding a burg. panel actually detracts from the system's performance and longevity. I've seen way more blown-up panels that were "grounded" than not.

What RLB described works great on paper and in theory, however, actually putting that scenario into practice is not feasable in 99% of installations.

Cold water pipe grounds were a stupid idea in the first place. I've never attempted that. I once saw an installation where some idiot grounded a system to a natural gas pipe!

True.

Huh?

a panel is "technically superior", it's also not required by law.

If the manufacturer's instructions say to ground it, code (not necessarily "law") says do so.

and longevity...

That's why almost every panel manufactuer's engineers design the system to be grounded, right?

putting that scenario into practice is not feasable in 99% of installations.

It would be nice if you actually knew what you're talking about, Cracker. What I spoke about -- bonded ground -- is the standard method of protecting electronics from lightning damage. It is well-documented online and in print. Not only that, but code describes the practice as well.

Regards, Robert L Bass