Are Natural Gas lines supposed to be grounded?

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RU482

Lifer
Apr 9, 2000
12,689
3
81
In my home, the furnace and hot water heater use natural gas. From the gas meter in to the appliances, the lines are Galvanized Steel. The furnace is fed directly via the galvanized pipe, the hot water heater connects via a brass union and flexible gas line.

So, tonight I happened to be in the basement. I was barefoot, and I touched the gas pipe and felt a shock. If I hold my finger to the pipe, I can feel what seems like mild AC current. I don't have my meter to check...

Anyway, are gas lines supposed to be grounded?
 
guyver01

guyver01

Lifer
Sep 25, 2000
22,135
5
61
250.104(B) of the NEC:

Other Metal Piping. Where installed in or attached to a building or structure, metal piping system(s), including gas piping, that may become energized shall be bonded to the service equipment enclosure, the grounded conductor at the service, the grounding electrode conductor where of sufficient size, or to the one or more grounding electrodes used. The bonding jumper(s) shall be sized in accordance with 250.122 using the rating of the circuit that may energize the piping system(s). The equipment grounding conductor for the circuit that may energize the piping shall be permitted to serve as the bonding means. The points of attachment of the bonding jumper(s) shall be accessible.
 
R

Rastus

Diamond Member
Oct 10, 1999
4,704
3
0
Modern lines are PVC and aren't grounded.

You might have a polarity reversal in one of your gas appliances between ground and neutral, that'll give you a low AC voltage on the pipe.

Older houses that the electric wiring was upgraded from 2-wire to 3-wire sometimes has the ground wire attached to a water pipe. The person who did it might have run it to the gas pipe by mistake, and he might have grounded the neutral by mistake too.
 
E

Eli

Super Moderator | Elite Member
Oct 9, 1999
50,419
8
81
Rastus said:
Modern lines are PVC and aren't grounded.

You might have a polarity reversal in one of your gas appliances between ground and neutral, that'll give you a low AC voltage on the pipe.

Older houses that the electric wiring was upgraded from 2-wire to 3-wire sometimes has the ground wire attached to a water pipe. The person who did it might have run it to the gas pipe by mistake, and he might have grounded the neutral by mistake too.
Click to expand...

This.
 
R

Rastus

Diamond Member
Oct 10, 1999
4,704
3
0
guyver01 said:
So.. is Galvanized Steel the same as PVC? i always thought PVC was plastic.

If not, then his lines should be grounded.
Click to expand...

PVC is plastic.

Lines should be bonded (attached bare metal to bare metal) to the appliances. Modern appliances have the metal case grounded to the ground wire. An old furnace that doesn't have the third wire might not have the cabinet grounded, it might even have the neutral bonded to it. With a new hot water heater or dryer, you could get the voltage.

That's the reason for the third wire. In the 2-wire days, you could electrocute yourself by touching a blender and a toaster at the same time.
 
I

iGas

Diamond Member
Feb 7, 2009
6,240
1
0
Yes it should be grounded by code.

I'm surprise that you are feeling a current when touching the gas pipe. Test the pipe using a meter, or a cheap probe light/pen/screw driver tester. Call an electrician and or your gas provider if a current truly exist.

That said most if not all gas pipes are grounded near or at the gas meter.
 
S

SirStev0

Lifer
Nov 13, 2003
10,449
6
81
guyver01 said:
meh.. i've always had a suspicion that Rubycon was really a guy lurking in disguise... and that he really wanted to be a troll.

now i'm proven right.

:D
Click to expand...
You are both morons. Her account was hacked. VB is notorious for bad database security. One of the last comments the hacker made was something along the lines of " whatever, ban the account, I'll just move down the list" So expect more drama.
 
guyver01

guyver01

Lifer
Sep 25, 2000
22,135
5
61
SirStev0 said:
You are both morons. Her account was hacked. VB is notorious for bad database security.. So expect more drama.
Click to expand...

uh huh... if that was the case, why isnt every account compromised? a "polite hacker" .. who hacks one account at a time? doubtful.

i don't think the mods would have BANNED the account (besides disabling it.. they didn't ban the account that compromised the forums..) unless they had some other info... VB records IP addresses of the poster. Perhaps the poster had the same IP address, or it was quite similar, indicating social engineering instead of hacking?

there's more going on than people are being told (which is always the case here)
 
S

ShawnD1

Lifer
May 24, 2003
15,987
2
81
Rastus said:
You might have a polarity reversal in one of your gas appliances between ground and neutral, that'll give you a low AC voltage on the pipe.
Older houses that the electric wiring was upgraded from 2-wire to 3-wire sometimes has the ground wire attached to a water pipe. The person who did it might have run it to the gas pipe by mistake, and he might have grounded the neutral by mistake too.
Click to expand...

I doubt this is the cause. The neutral wire with less than 1 Ohm impedance would need to have a ridiculous amount of current before it would have a voltage high enough to feel. For example, I can touch my hands across a 12V car battery and not feel any shock since 12V is not enough to put any noticeable current through me. 120V has enough to knock me on my ass.

One possibility is if the house is not solidly grounded. If the ground wire had maybe 100 Ohms impedance instead of ~1, a little bit of ground current would create quite a bit of voltage. A resistive ground is sometimes intentional, but in a house it's more likely the result of bad wiring. Bad splices with very weak connections can cause bad grounding. Worse yet, a ground fault in such a system often causes house fires because the amount of heat generated is directly proportional to resistance, which would be the highest at the splice where the connection is weak.

OP, buy a new meter and check your voltages. Tell us the following AC voltages:
gas to hot wire
gas to neutral wire
gas to ground wire

You might need to run an extension cord to test this if there are no receptacles near the gas line.
 
Analog

Analog

Lifer
Jan 7, 2002
12,755
3
0
There should be a ground rod near the service entrance to the house. That ground wire should be bonded to the lighting panel and a cold water pipe. All other metallic pipes need to be bonded as well. Most black iron pipe is defacto bonded when they are piped into appliances such as the hot water heater (via copper water pipe to the device) or the furnace (via electrical conduit), stove and dryer in the same manner. I would go ahead and bond it anyway, cheap, easy and the right thing to do.
 
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