CSST Bonding

[petersonra]

Case in point: My 1957 house just had the gas line to the water heater (in the carport) rust through. In such a repair, I expect many guys would simply cut the pipe, thread the ends, and use a length of CSST. Remember: they're not allowed to use unions under the house, and taking the line apart from the end is a lot more work!


Neither fuel gas code restricts the use of unions in a crawl space, only in concealed locations, with the exception in the National fuel Gas Code that will allow a repair in a concealed location to use a union and center punch the retaining nut to prevent it from backing apart.


In your scenario of black pipe and adding a section of CSST to a stationary piece of equipment a # 6 copper conductor or equivalent would need to be run to bond the CSST back to the Grounding Electrode System.

Wouldn't it make sense to allow the bond in such a case to be made to the other end of the black pipe and let the black pipe be the GEC back to the bonding point? It seems to me that no matter what you do the black pipe is going to act as a GEC anyway in this kind of case. .

 

[Gregg Harris]

Wouldn't it make sense to allow the bond in such a case to be made to the other end of the black pipe and let the black pipe be the GEC back to the bonding point? It seems to me that no matter what you do the black pipe is going to act as a GEC anyway in this kind of case. .

Yes the black pipe can be bonded with the #6 or larger. What ever is the shortest distance to the Grounding Electrode System. I was trying to emphasize was that the original gas piping system when all black steel would follow 250.104 by using the equipment bonding conductor to accomplish the bonding.

Now that it is a Hybrid system the #6 or equivalent is required to comply with the minimum bonding requirements of the MFG. and NFPA 54 (National Fuel Gas Code 7.13.2, International Fuel Gas Code 310.1.1, and International Residential Code G 2411.1.1


Case in point: My 1957 house just had the gas line to the water heater (in the carport) rust through. In such a repair, I expect many guys would simply cut the pipe, thread the ends, and use a length of CSST. Remember: they're not allowed to use unions under the house, and taking the line apart from the end is a lot more work!

 

[petersonra]

Now that it is a Hybrid system the #6 or equivalent is required to comply with the minimum bonding requirements of the MFG. and NFPA 54 (National Fuel Gas Code 7.13.2, International Fuel Gas Code 310.1.1, and International Residential Code G 2411.1.1

I fail to see how running another bonding conductor will resolve whatever is going on here. It is already bonded via the EGC of the device it feeds.

If the problem is that somehow lightning is causing holes in the CSST, wouldn't better bonding make it worse?

 

[kwired]

I fail to see how running another bonding conductor will resolve whatever is going on here. It is already bonded via the EGC of the device it feeds.

If the problem is that somehow lightning is causing holes in the CSST, wouldn't better bonding make it worse?

Ding, ding, ding we have a winner

Running a heavier bonding conductor to the line lowers resistance to grounding electrode system, meaning if higher power is available in the lightning event the more potential current possibly can flow.

The CSST is still energized with a 12 AWG or a 6 AWG bonding jumper, possibility of flashing over to other objects is not likely to change much and the wall of the tubing is very thin and inside is combustible gas, I'll take black pipe even with concealed fittings anyday, over this crap. Many HVAC guys don't even own a pipe threader and couldn't run black pipe if they had to, that is why they love the stuff.

 

[curt swartz]

I'm not going to get into the debate about bonding right now but wanted to make a quick comment about the restriction of the use of unions. When a section of gas piping in the middle of the run needs to be disassembled there is no reason to use unions or take the entire run apart. Left/Right nipples and couplings are pretty much a standard item on any plumbers truck that is doing gas piping. One end of the nipple and one end of the coupling is reverse threaded allowing installation with out disturbing the rest of the piping.

I have only seen CSST used on 3 residential projects. Never on commercial. All 3 projects we done by the same plumber in his 60's that is a one man shop. He doesn't even own threading equipment. All of the other plumbers I work with (big and small shops) say they will not touch CSST.

 

[kwired]

I'm not going to get into the debate about bonding right now but wanted to make a quick comment about the restriction of the use of unions. When a section of gas piping in the middle of the run needs to be disassembled there is no reason to use unions or take the entire run apart. Left/Right nipples and couplings are pretty much a standard item on any plumbers truck that is doing gas piping. One end of the nipple and one end of the coupling is reverse threaded allowing installation with out disturbing the rest of the piping.

I have only seen CSST used on 3 residential projects. Never on commercial. All 3 projects we done by the same plumber in his 60's that is a one man shop. He doesn't even own threading equipment. All of the other plumbers I work with (big and small shops) say they will not touch CSST.

I don't understand the Left/Right nipples and couplings thing - something has to be able to remain stationary while turning something else - just like a standard union, if we are talking about threaded fittings.

I am somewhat impressed that there is that little CSST being used. Around here that is all you see from the HVAC guys. They may run limited black pipe but it is all pre cut nipples or specific lengths and most do not even have a pipe threader. Everything else is CSST. You may find occasional copper tubing for LP but that is becoming more rare, but I would rather see that than CSST.

 

[renosteinke]

Now, I'm no plumber, so my knowledge of that trade is extremely limited.

I believe that the prohibition of unions in crawl spaces is based upon 112.3.2 of the uniform Plumbing Code. This section reads, in part: "Where gas piping is to be concealed, unions .... shall not be used." Many other fittings are also prohibited, where the piping is run in 'concealed' spaces.

True, 112.3.2(4) does allow the use of a center-punched union "where necessary to insert fittings into pipe that has been installed." So, a union might be used as part of a repair. It sure looks like my understanding of the 'prohibition' was too broad.

I suppose we might debate what is meant by 'concealed,' but I suspect that discussion has already taken place. Reference to working on the pipe after installation seems to infer that 'concealed' might very well also be 'accessible,' as in a crawl space.

Now, we run into a code conflict when we look at UBC 112.13(B), which bluntly states that "gas piping shall not be used as a grounding conductor or electrode." If our CSST grounding is any distance from the CSST, the pipe is clearly being used as a GEC.

I suspect here is where we must distinguish between a 'grounding conductor or electrode' and a 'grounding electrode conductor.' For example, we are not allowed to use the gas pipe as a means of adding a 'ground wire' to an older home with two-prong receptacles. That would be a 'grounding conductor.'

Nor are we using the gas pipe as an eletrode, though it enters the earth (where it feeds the meter). Rather, we are using the wire as a GEC to connect the pipe to the actual electrode, the ground rod.

 

[Gregg Harris]

Now, I'm no plumber, so my knowledge of that trade is extremely limited.

I believe that the prohibition of unions in crawl spaces is based upon 112.3.2 of the uniform Plumbing Code. This section reads, in part: "Where gas piping is to be concealed, unions .... shall not be used." Many other fittings are also prohibited, where the piping is run in 'concealed' spaces.

True, 112.3.2(4) does allow the use of a center-punched union "where necessary to insert fittings into pipe that has been installed." So, a union might be used as part of a repair. It sure looks like my understanding of the 'prohibition' was too broad.

I suppose we might debate what is meant by 'concealed,' but I suspect that discussion has already taken place. Reference to working on the pipe after installation seems to infer that 'concealed' might very well also be 'accessible,' as in a crawl space.

Now, we run into a code conflict when we look at UBC 112.13(B), which bluntly states that "gas piping shall not be used as a grounding conductor or electrode." If our CSST grounding is any distance from the CSST, the pipe is clearly being used as a GEC.

I suspect here is where we must distinguish between a 'grounding conductor or electrode' and a 'grounding electrode conductor.' For example, we are not allowed to use the gas pipe as a means of adding a 'ground wire' to an older home with two-prong receptacles. That would be a 'grounding conductor.'

Nor are we using the gas pipe as an eletrode, though it enters the earth (where it feeds the meter). Rather, we are using the wire as a GEC to connect the pipe to the actual electrode, the ground rod.

A crawl space is accessible, concealed would be behind a wall where access would require removal of drywall, plaster etc.

The gas line is isolated on the supplier's side of the meter, so bonding on the customer side bonds to the electrical system and the under ground gas service is not a grounding electrode since it is isolated.

 

[SparkyRules]

CSST bonding

CSST bonding

Hi All,

It seems to me, if we are bonding then also grounding CSST pipe to JUST run a #6 from the manifold to the GRC system would be ineffectual to thwart a lightning strike. Would you not also have to bond around each separate segment of the CSST pipe? If I read the gas code correctly it would require at least the 1st section from the NG meter to be bonded to the 1st fitting (manifold?) (comments anyone?) and then that also grounded ( all with a #6). However what is to keep lightning from not running thru any of the "branch" pipe on the load side of the manifold to this point which now seems to be a more attractive path for lightning now that we have just bonded and grounded it! I am getting called for home sales to fix this but there is no clear fix for this. Also in our jurisdiction this is not even considered a permitabled job, yet, as the inspectors have no part of the NEC they can reference. Comments? :?:?:?

SparkyRules.... many small jobs, no simple ones, many simple jobs no easy ones!!!

 

[Dennis Alwon]

The gas code is in effect here and I believe it calls for the CSST to be bonded at any point before it enters the building. Generally there is a piece of black iron that is stubbed into the building. It s at this point where one would bond the pipe. There is no need to bond any further.

 

[acrwc10]

Well now that the big orange is selling CSST I am certain you are going to see much more of it installed. The issue with bonding it seems to come down to one question, "where to bond it"? you only need to bond it at the starting point of the CSST or closer to the Load side of the meter. Bonding it is only to reduce the problem caused by an "indirect lightning strike". Most gas supply systems have a dielectric fitting on the meter or before going into the earth, so they are not becomming a "GEC" they are simply Bonded. I have seen many installations of CSST and most houses have a gas flex to every appliance already, they are thinner than CSST and seem to work out long term. PEX, and NM have had the same arguements when they were new and they are still in use today with more and more people accepting them. Like it or hate it it's here to stay. I would worry more about CSST getting a hole rubbed in it over time by contact with something else in the building, or a nail getting driven into it.