Conditional PG&E PTO and inverter downsizing

[YRide]

I am saying my efforts to use these for a contractor haven't been fruitful. I cannot speak to any reduced gas meter clearances.

Can you point to where this slam shut valve is specified in the green book? Greenbook Manual Online

Haven’t found in green book. Just going off what our territory PGE Gas lead mentioned…as well as wrote up a work ticket for.

 

[Vines]

Haven’t found in green book. Just going off what our territory PGE Gas lead mentioned…as well as wrote up a work ticket for.

PM me a name or contact if you can. I'll follow up and see what is the story.

 

[hiltxan]

This stuff drives me nuts. Who decided 12" is ok for a slam shut? Who decided 36" for the gas riser clearance? Has there ever been an explosion from a gas riser being too close to a meter or electrical panel? The most memorable gas explosion was in San Bruno and that was from a 30" gas pipeline, not a gas riser next to a panel. In fact, I can't find on the internet one instance of a gas riser exploding next to a main panel.

Natural gas needs to be a certain ppm before even reaching ignitable levels. Has anyone even measured in an open area how high ppm can develop from a gas riser or pressure relief valve and how does it dissipate? I'm sure it's on logarithmic scale. Then you also have to factor in the density of natural gas (which is lighter than air) and calculate fluid dynamics since gas does not travel in a 2D space. It could also be a way to deter solar installs and PG&E making it difficult on purpose.

I work in medicine and always refer to data and research. We deal with admin and nurses all day who make up nonsense rules that have no data to back them up and we are forced to follow just because some admin person in an office decided on rules that just sound good but without any research to back it up. I have to constantly fight them back at work.

 

[jgleigh]

Kind of like not using your cell phone while pumping gas? Silly rules get implemented due to FUD or one isolated incident.

 

[BGbreeder]

This stuff drives me nuts. Who decided 12" is ok for a slam shut? Who decided 36" for the gas riser clearance? Has there ever been an explosion from a gas riser being too close to a meter or electrical panel? The most memorable gas explosion was in San Bruno and that was from a 30" gas pipeline, not a gas riser next to a panel. In fact, I can't find on the internet one instance of a gas riser exploding next to a main panel.

Natural gas needs to be a certain ppm before even reaching ignitable levels. Has anyone even measured in an open area how high ppm can develop from a gas riser or pressure relief valve and how does it dissipate? I'm sure it's on logarithmic scale. Then you also have to factor in the density of natural gas (which is lighter than air) and calculate fluid dynamics since gas does not travel in a 2D space. It could also be a way to deter solar installs and PG&E making it difficult on purpose.

I work in medicine and always refer to data and research. We deal with admin and nurses all day who make up nonsense rules that have no data to back them up and we are forced to follow just because some admin person in an office decided on rules that just sound good but without any research to back it up. I have to constantly fight them back at work.

I'm with you. By the way, the lower flammability limit (ignition limit) for methane is 4.4%

However, I also go the other way, and ask who in their right might thought that enclosing gas meters and service panels in the same or adjacent boxes was a "good thing"? Getting to 4.4% methane in the open air takes a lot of methane, getting to 4.4% in a 2'x2' enclosed space (with the electrical panel above the gas lines!) is much easier. Why put both an arc source and a flammable gas adjacent to each other if you do not absolutely have to?

All the best,

BG

 

[wwu123]

Kind of like not using your cell phone while pumping gas? Silly rules get implemented due to FUD or one isolated incident.

I remember in Japan, self-service gas stations were not allowed until about 1998, due to concerns about self-immolation; not sure if it's still the case, but for a while, the self-service stations had to install these fire suppression systems dangling menacingly just a few feet above your head, "just in case".

Apparently not just smokers (still prevalent there) and cell phones, but also "static electricity" from women's clothing? But the one incident I read about the latter, the ignition occurred when the woman unscrewed the gas cap on her car, had nothing directly to do with the gas station at all, or even pumping of gas - and why hasn't such ever occurred in the U.S., if it's such a risk?

 

[yblaser]

I remember in Japan, self-service gas stations were not allowed until about 1998, due to concerns about self-immolation; not sure if it's still the case, but for a while, the self-service stations had to install these fire suppression systems dangling menacingly just a few feet above your head, "just in case".

Apparently not just smokers (still prevalent there) and cell phones, but also "static electricity" from women's clothing? But the one incident I read about the latter, the ignition occurred when the woman unscrewed the gas cap on her car, had nothing directly to do with the gas station at all, or even pumping of gas - and why hasn't such ever occurred in the U.S., if it's such a risk?

Not to take this further off topic but they do occur in the US. Best I could find on google is that they occur at a rate on the order of 10 times per year which is quite rare given the number of fill ups in a year. I would be curious if the rates are lower in states that require vapor recovery nozzles when accounting for weather differences. It does appear that it occurs more often to women and there are several theories on why.

 

[hiltxan]

I'm with you. By the way, the lower flammability limit (ignition limit) for methane is 4.4%

However, I also go the other way, and ask who in their right might thought that enclosing gas meters and service panels in the same or adjacent boxes was a "good thing"? Getting to 4.4% methane in the open air takes a lot of methane, getting to 4.4% in a 2'x2' enclosed space (with the electrical panel above the gas lines!) is much easier. Why put both an arc source and a flammable gas adjacent to each other if you do not absolutely have to?

All the best,

BG

Yea, I'm somewhat worried about the enclosure. I'll probably buy a natural gas detector from amazon and check myself periodically just for a piece of mind. Also might end up going crazy and checking every connection around the house as well as routine maintenance.

 

[BGbreeder]

Yea, I'm somewhat worried about the enclosure. I'll probably buy a natural gas detector from amazon and check myself periodically just for a piece of mind. Also might end up going crazy and checking every connection around the house as well as routine maintenance.

Can I suggest perhaps adding some (unpowered) vents high/low to dissipate any emissions? It isn't uncommon to have relief valves burp gas occasionally, and the pressure reducing diaphragms do get leaks overtime. You probably want to put some 1/8"(+/-) mesh across the openings to keep out insects like bees and wasps as well as mice... Mice can get through anything larger than a 1/4" hole.

Unless your sense of smell isn't great, you can probably smell or find leaks with some dish soap diluted in water as quickly as a meter, and for a lot cheaper. I use an old toothbrush to coat all sides of a joint.

There are lots of homes with gas, and there are rarely any untoward events...

All the best,

BG

 

[hiltxan]

Can I suggest perhaps adding some (unpowered) vents high/low to dissipate any emissions? It isn't uncommon to have relief valves burp gas occasionally, and the pressure reducing diaphragms do get leaks overtime. You probably want to put some 1/8"(+/-) mesh across the openings to keep out insects like bees and wasps as well as mice... Mice can get through anything larger than a 1/4" hole.

Unless your sense of smell isn't great, you can probably smell or find leaks with some dish soap diluted in water as quickly as a meter, and for a lot cheaper. I use an old toothbrush to coat all sides of a joint.

There are lots of homes with gas, and there are rarely any untoward events...

All the best,

BG

Thanks for the advice.

The door does have an unpowered vent on the bottom half if that's what you're referring to? Pressure relief valve is actually outside of the closet. There's also this board separating the panel and the gas meter - maybe PG&E thought that was enough to separate the gas compartment from the electrical meter/panel. But then AT&T and comcast put all their low voltage equipment next to the gas as well....

Amazon has these detectors that are like $50-$80 and seem legit, like the same ones PG&E uses. I've definitely used the dish soap method when I connected my own lines such as the clothes dryer, but the detector just seems like a good inexpensive tool to have handy anyways so I'll try it out.

 

[BGbreeder]

Thanks for the advice.

The door does have an unpowered vent on the bottom half if that's what you're referring to? Pressure relief valve is actually outside of the closet. There's also this board separating the panel and the gas meter - maybe PG&E thought that was enough to separate the gas compartment from the electrical meter/panel. But then AT&T and comcast put all their low voltage equipment next to the gas as well....

Amazon has these detectors that are like $50-$80 and seem legit, like the same ones PG&E uses. I've definitely used the dish soap method when I connected my own lines such as the clothes dryer, but the detector just seems like a good inexpensive tool to have handy anyways so I'll try it out.

That looks like a nice vent! I was thinking also of an upper vent to let the methane out of the upper electrical section, but with a solid floor between the two, and the opening to the crawl space and that large vent, it seems less important.

All the best,

BG