I was asked to bond the yellow gas line today by one of my customers. I have seen this done on a few jobs by HVAC guys but never the same way or with any good explanation as to method or code reference. Some say bond some say grounding, some don't know? Anybody have any insight?
Ob
Ob:
Official determination here (NJ) is the bonding is done thru the appliances that are connected to the CSST; ie: the egc within the circuit feeding the appliance. There is no 'direct' bond of any gas line.
I'm not sure where this will all end up; as I see it, there's more than the usual amount of room for confusion and debate.
UL is very strong in the electrical field; they're not quite as strong in the 'mechanical' trades. Therefore, there is a lot of perfectly fine equipment out there that has never been near a UL office. Indeed, for many items there is not even a UL standard. The end result is that we can't just hide behind the UL label.
So, let's look at the problem we're trying to address.
I don't think the issue is with short 'appliance whips' of CSST as much as it is with places where CSST is used as the primary material for gas lines. Yhis leaves us with two places where bonding MIGHT be required.
The first is at the gas main, with, perhaps, a jumper around the meter.
The second is at the appliance. If the appliance does not use electricity - neither my range nor my furnace does - then there is no requirement to bond the appliance. Yet, the furnace has a vent flue, suggesting a point for lightning to strike.
I'm not sure how much protection against lightning is provided by even a #10 wire from the appliance to the ground rod. It appears that lightning doesn't even follow the CSST, as much as 'jump' from rib-to-rib of the corrugations. This is how the pinholes are made. We might have a problem here that we cannot prevent.
It's possible that the best approach would be to have a permanantly installed pressure gauge at the meter, allowing you to pressure test the line at any time.
The grounding conductor in the cord / circuit to a gas appliance is all that the electrical code requires.
However, the manufacturer's of CSST gas piping require that their system be bonded. Many Mechnical codes also require it. The bond for the CSST is to reduce / prevent lightning strikes in the area from following the gas line into or out of the building and damaging the CSST. The recommended installation is to use a bond from the servcie equipment to the point where the gas line enters the building as black pipe before it is transitioned to CSST. If that is not possible then connecting the bond to the CSST manifold where the gas pipe is tapped to serve the different appliances. If that is not possible a connection at the CSST connector, (frequently shown in the manufacturers literature,) is allowed. it should be noted that there are no listed pipe clamps designed to fit on the flat sided connector fitting. The bond is never to be on the CSST itself.
As a side note in Indiana the CSST tubing is to be kept 2 inches away from conductive surfaces except at the connection.
It should be noted that gas piping is not allowed to serve as a grounding electrode.
The recommended bond size is # 6 Cu. for residential. For commercial jobs the manufacturer advises having an engineer determine the wire size.
As a final caveat the makers of CSST note that in areas subject to lighting a lighting protection system should be installed. All this so the HVAC guys don't have to thread pipe. And when it fails it is still your fault.
Sorry to throw Canadian electrical code into the discussion but there are a few points that cross boarders.
The CEC used to allow any Gas appliance with an electrical supply to bond the entire gas system. A few high energy incidents killed that as more than 1 bonding conductor was burned off from a lightning strike.
A gas meter has a dielectric fitting that is supposed to isolate the underground pipe from the interior one. Current Canadian code requires a minimum #6 bonding conductor to be connected to the interior gas piping. The gas company likes us to use the iron pipe nipple at the meter on the house side before they go to soft copper tubing. The SS yellow jacketed pipe is not common for single houses and generally only in multi family dwellings.
Other advice about lightning protection is sage advice here too.
The purpose of the bonding is to dissipate energy coming in from outside or accidental from the interior.
Out my way the standard utility distribution is plastic right up until it 'airs out'. ( stubs up to the outside of the building to be metered )
THAT is the only element to be bonded. Because of the non-conducting seals involved in and around the gas service various jumpers bond each element, but the main gas bond is to the above grade internal exposed metallic main piping.
I all my days I've never seen bonding jumpers at the point of use appliances.
This scheme establishes an equipotential plane even in the face of lightning -- which is critical.
You will nopt find this requirement in the NEC. It is a HVAC requirement. It has become a problem that this stuff is not bonded and it connot clear a short/lightning strike. It has happened to my customers nieghbor. A fire actually started from this. I spoke to a local inspector and he gave me his version of the bonding, but told me to call his office for the actual paperwork. I have not heard back as of yet. I had a HVAC guy run a #6 into my panel on another job(made a mess of my panel) the city inspector said Ok but was un fimaliar with this requirement. I have spoken to 2 other HVAC guys I know and each has a diffrent version. That is why I figured this was the place to go?
Ob
Ob:
Try this for one CSST mfg info.
omegaflex.com/trac/technical/specsheet_new2009.PDF
Our plumbing AHJ got mfg spec with the 'you must bond' a while ago. But...State says no direct bond, only bonded thru EGC of appliances