ECN Forum
Posted By: schenimann checking gas bond - 01/21/11 04:37 AM
Hey guys

I picked up some work for a local fireplace store bonding the gas lines on installation. They have been installing them for years but only recently failed for a missing gas bond to the black pipe. I had already done several bonds for the tract pipe but apparently they had no idea that a bond is required for the black pipe. It actually works out good, now they call me on every installation to do the bond.

The black pipe can be bonded anywhere on the pipe. It may be at the service, furnace, water heater, crawl space, attic, etc. Is there a way to check for bonding that is not easily visible. Can I do a simple continuity test, hot to ground? If the pipe runs against something that is grounded, the meter would show ground but it is not truly bonded. It would still be a permit and a service call, but would save the work.
Posted By: leland Re: checking gas bond - 01/21/11 05:56 AM
How are these fire places operated?
Where/what is the final gas connection?
What is the final gas termination?

If any of these items are cord and plug connected,then they are bonded thru the EGC.
If they are hard piped into a unit,that is hard wired IE: furnace,boiler etc..They are bonded thru the EGC or the water piping.

I see no need nor does the code making panel for additional bonding.

Good score for no reason. Charge accordingly.
Posted By: Tesla Re: checking gas bond - 01/21/11 04:55 PM
Ahem...

Gas line have to be boned when the utility is bringing gas in by plastic AND the metallic piping is a retrofit -- it wasn't bonded during the original construction.

Simple static electricity is enough to spark off natural gas. The last thing you want is for an unbonded pipe to build any charge under any condition.

Think lightning, vehicles driving into the home, crazy kids...

-------

The retro-fit 'fireplaces' I'm seeing are pure electric fakes. Out my way the AHJ has shut down fireplace permits.

Thusly, any home with a pre-existing fireplace pulls a premium price -- generally $5,000 per fireplace!
Posted By: Obsaleet Re: checking gas bond - 01/22/11 05:25 AM
I believe he ids talking about bonding the yellow flex pipe to the black pipe. If you are connecting this to the grounding electrode it is no longer a bond but a ground. This is a violation in most gas companies eyes. The do not want any of there piping carrying stray voltage to ground. Aloose connection gets moved and boooom!

Ob
Posted By: Tesla Re: checking gas bond - 01/22/11 11:20 PM
Obsaleet...

OP is bonding the BLACK PIPE to the GEC system.

Read the second half of the Original Post.

BTW, that's EXACTLY the way our AHJ insists, too.

Posted By: leland Re: checking gas bond - 01/23/11 12:49 AM
Correct me if I'm wrong,Or educate me If I missed it.

The yellow flex gas pipe is metallic inside,all fittings are metal,change over to black steel, via threaded black coupling, and pipe to fixture-furnace -heater etc.

Fixture is wired and grounded,does this not in turn bond the gas pipe?

thanx,
Posted By: Tesla Re: checking gas bond - 01/23/11 05:06 PM
Leland...

Perhaps so.

But what if the building's occupant doesn't install an appliance?

In such a case you've got a building with gas in black pipe terminated in a nipple and ball valve -- not bonded to the building.

My AHJ will not accept some cheezy EGC to bond the black pipe to the GEC. Instead it must be a massive conductor sized like the water bond and structural bond.

That's not as tough as it seems. The gas SERVICE is right next to the water SERVICE. So it is but a small matter to jumper them together.
Posted By: Niko Re: checking gas bond - 01/23/11 05:29 PM
Originally Posted by schenimann
Is there a way to check for bonding that is not easily visible. Can I do a simple continuity test, hot to ground? If the pipe runs against something that is grounded, the meter would show ground but it is not truly bonded.


If you do a simple continuity check it will probably read that is connected to a grounded body. However, it may be just TOUCHING the water pipe. The easiest way which i am sure you already know, is connect the cold/gas/hot pipes at the water heater which can be visually verified.

Some of local AHJ require bonding of the gas pipe with at least a #6.
Posted By: leland Re: checking gas bond - 01/23/11 07:12 PM
Thank you Tesla,

I have never run into this situation in my area.
But do understand the issue better now.I will be more observant.

I do however,bond the duct work (with #10) between the AH and the flex-transition to building duct- (resi),not all flex though,as I probably should.
Posted By: leland Re: checking gas bond - 01/23/11 08:10 PM
Now that I think about it... Hurts my lil' brain-

My theory of the EGC bonding,how about the appliance (stove etc) that is 3 wire- that bond is actually a grounded conductor....

Now I got a headache. frown
Posted By: Obsaleet Re: checking gas bond - 01/23/11 08:57 PM
If the OP is running to the main that is a ground not a bond. He has now created a supplimental ground, same a cold water ground. The metal (AL) has been proven to not be adaquate to clear a fault landing gas pipe. it attempts to travel through the yellow pipe and burns a hole through it leading to bad things. The ground of the appliance is its return path to ground. I have just gone through this with one of our local AHJ and my research said the same thing how ever he insisted that I run the wire back to the panel. A meeting and a very rough quick drawing straightened him out.
Remember bonding is not grounding, but some bonds are grounding. Think swimming pool bond.
Posted By: Tesla Re: checking gas bond - 01/23/11 11:45 PM
To my mind a supplemental ground is like another ground rod and such.

Bonding the black pipe provides no additional path to the earth worth mention.

The local gas company delivers the gas via buried plastic. Then it is connected to an extremely short stub of black pipe on the way to the gas SERVICE.

With our dry soils and climate... No one would consider that short path any kind of supplemental.

Every additional element brought into the GEC System does so by being bonded to it to create/extend an equipotential plane.

Connecting the neutral jumper causes the grounded conductor to be --- grounded.

All bonding connections are for fault conditions only/maintaining an equipotential plane.

Grounded conductors and their path down into the bowels of the GEC are expected to carry the return current/unbalanced current.

That's my frame of reference...

SERVICE bonding is typically 3/0 Copper -- by specification.

However, from time to time Aluminum has been used for some bonding connections when the ENTIRE run is above ground and conditions are suitable. ( Would never install near the sea coast, etc.)

Again, I only work commercial so some of my practices may not line up with residential practices. I do normally get inspected by the 'top dog' in the area. For example in downtown Oakland all of the high rises are inspected only by the City's Chief Inspector. He doesn't miss a thing.

I must say that in residential settings our AHJ just won't allow aluminum, period, in field wiring/bonding. The Poco loves it though. If your SERVICE is so huge that Copper is required ( over 3,000 Amps 208V or 480V ) you're tapped big time and the stuff is brought out just for you. It is NOT stocked. Normally SERVICES of that size move to bus duct and put the Poco Xfmr immediately outside the building.

And in my area the Poco is the Gasco.

Posted By: sparky Re: checking gas bond - 01/24/11 12:28 PM
man, this thread needs a 780 druid dude, kinda hard to find up my way, they've an interesting take on equipotential planes.

according to thier theory (or what i understand of it) , a 1,000,000 volts on one side of any given 'plane', and 500,000 volts on the other does the more damage in a split second than 1,000,000 volts evenly distributed


everything's supposed to blow up evenly.... crazy


~S~
Posted By: renosteinke Re: checking gas bond - 01/24/11 02:34 PM
This area is somewhat problematic, if for no other reason than that you can't see which way the electricity is flowing.

A grounding elecgtrode is supplsed to always carry a wee bit of current. This is problematic with gas lines, as we don't want to make a spark when they're working on the gas main.

This is countered by the guy at the last "Soares seminar," who stressed the need to bond the gas line to clear faults if it should somehow become energized. As others have mentioned, this is best done at the appliance.

Yet, you still have the OP's basic question of "how do I know it's a good bond?" As best I can tell, the only way to do know is to test it the same way we test other bonds and ground rods: disconnect the wire at the source, and use one of those fancy impedance testers to induce a charge on the line- and actually measure how quickly that charge dissipates. Unlike a simple resistance test, this test gives you some idea as to the ampacity the 'electrode' can carry.

If your bond 'fails,' then you'll have to do a second test, with another bond made between the panel and the pipe. This is because there remains the possibility that the pipe is isolated from the earth, and there is no 'ground path' once you disconnect the one you're testing.
© ECN Electrical Forums