Whats to argue with? NEC is as plain as day on the subject. However, this is never enforced here in WV as far as I know. Gas company guys usually get real excited when they see the bond conductor. Don't know why, there is almost always some other unintentional path back the the service neutral.
Few things are harder to put up with than the annoyance of a good example.
I know this issue deals with the US, but in Ontario, Canada, we The Electrical Safety Authority (formerly Ontario Hydro Inspection) adopted this practice of BONDING the interior gas piping in 1996 and have been enforcing it regularly.
SUBJECT: BONDING INTERIOR METAL GAS PIPING (SUBRULE 10-406(4))
Rule 10-406(4) requires that all interior metal gas piping which may become energized shall be made electrically continous and shall be bonded.
Questions have been asked on specific circumstances where the subrule applies, who is responsible for installing any bonding conductors and the acceptability of a particular way to meet the requirements.
Bonding in accordance with Subrule 10-406(4) is required for:
1. New buildings with gas piping installed at that time. The contractor responsible for making application for inspection of the electrical service and panelboard is responsible for the bonding.
2. Electrical service upgrades in buildings with gas piping. The contractor responsible for making application for inspection of the service upgrade is responsible for the bonding.
3. Gas piping being installed for the first time in a building with no change in the main electrical service but with electrical work associated with appliances supplied by the gas piping. The contractor responsible for making application for inspection of the electrical work is responsible for the bonding.
A #6 bonding jumper (or larger), from the metal gas pipe after the meter to the closest cold water pipe, is an acceptable means of bonding the metal gas piping as per Sub Rule 10-404(4), provided the Electrical Inspector is satisfied the water pipe is part of an electrically continuous path to the system grounding conductor. In other words, it is not necessary in every case, to bond the metal gas piping directly to the system grounding conductor.
Tony Moscioni Electrical Inspector Electrical Safety Authority
Its funny you guys brought this up. Here in NJ, the gas company DOES NOT want us to bond to the gas pipe. Even though the NEC requires it. The Gas co. and the state feel that through normal grounding situations ( a gas stove, gas dryer, etc. with a 3 prong plug, will provide the proper grounding path. Well, today I just inspected a house which had a problem on Mon. It seems the gas co was in the area changing over their pipes, (making them larger or something.) and when they disconnect tis one house, a man was shocked, the gas piping started to "pop", and there were sparks. The power co. was called, the fire trucks rolled, police, etc. Long story short, the neutral on the service was bad, as was the cold water ground. (as far as I know). So I inspected a brand new 100 amp over head service today with a new grounding electrical conductor to the water service. The homeowner also lost a TV, garage door opener, and several surge suppresors.
Tom - Agreed, I don't see the argument either, but it sure seems to rear it's ugly head on a regular basis.
Tony - Thanks, good to hear from another source, and that does lend credence to the enforcement.
HE - I really expect we have more problems out of this than ever gets reported. If a house blew up, it would likely be reported as an "electrical" problem, and likely no one would ever publish that some inspector enforced the code wrong.
Thanks for all posts here, it really is good to hear some varying opinions.
sparky66wv Wrote: Assuming there's at least 10' of metallic pipe buried outside of the structure, how would bonding to the pipe be any different than using it as a third grounding electrode?
The only difference I see is that #4 AWG must be used rather than the exception to use #6 for GEC...
Other than that, aren't they technically the same?
sparky66wv You have hit on the heart of the problem. My solution is to ask the pipe fitters to install a dielectric union between the utility and interior piping. One plumber said he would only do it as an extra and was shocked when I wrote the order. The underground piping that is installed for gas these days is usually coated to prevent corrosion so it won't be an effective electrode anyway until it is all the way back at the main under the street. I do completely understand why the gas utility does not want there piping carrying the neutral currents. What is needed is a change in the fuel gas code to require isolation of the underground piping from the interior piping through the use of dielectric unions. As you have already pointed out the Equipment Grounding Conductor (EGC) of every circuit to a gas appliance plus the nearly inevitable contact between other grounded objects and the gas piping makes deliberate bonding a better thing than the existence of high impedance accidental or incidental grounds to that piping. -- Tom
"This alternating current stuff is just a fad. It is much too dangerous for general use" Thomas Alva Edison
The gas equipment I have seen lately does contain pressure fittings and regulators. This stuff is often not conductive, similar to water meters that we must bond around. The EGC attached to an appliance occasionally does not bond the pipe. That is my only contention with this one.
The difference is Sparky, it may function as an electrode, but we cannot count on it per Code. Prior to about 84, we were required to treat it as such, but the NFPA recognized that plastic pipe was becoming the prevalent method in the gas industry.
A lot of guys mistakenly took this as an edict that we were not allowed to bond it, obviously a very big mistake.
The VA state VBCOA site had a post from Wash. Gas, who agreed that it is a big problem, and that they require it to be bonded ON THE HOUSE SIDE, the problem comes when it's on the street side. I was real glad to see it addressed by Mr. Johnston.
[This message has been edited by George Corron (edited 09-19-2002).]
250.104(B) has a clause that leads me to belive that the EGC for, say, the furnace blower motor and ignition/logic circuit would suffice. Would there need to be an actual clamp with say, a #12 green going to it from the device box, or is the internal bonding from the EGC in the device box, throught the frame of the furnace, to the gas pipe enough of a bond?
-Virgil Residential/Commercial Inspector 5 Star Inspections Member IAEI
The gas utilities have used dielectric fittings between the building piping and the underground piping for at least 40 years in this area. I thought that all gas utilities isolated their underground distribution from the building piping, but apparently not. In this area, it is no longer any type of problem as all of the gas underground distribution up to 800 psi is nonmetallic pipe. As far as an actual bonding connection, many code authorities agree that the mechinical connections on a gas appliance that has electric power is a sufficient bond to comply wiht 250.104(B). In some cases the mechinical connection may be good enough, but on other appliances a bond directly to the gas pipe would be required. This should be addressed by CMP 5 as the wording in the current code does not clearly require an actual bond to the pipe. Don