I work in NJ. I have an inspector looking for PVC expansion fittings on every piece of conduit we install on the outside of a residence or building. 10' to 20'long verticle runs. He's the only one requiring this. I asked other sub code officials in nearby towns and they do not feel the same way. May be ive got the temperature chnge value wrong???
PVC expansion fittings
- Thread starter cvar
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wanderer20001us
Senior Member
Re: PVC expansion fittings
352.44 indicates that expansion fitting are only required if the expected change in length in straight runs between fixed items is 0.25 in. or greater.
In a 10' section of PVC (352.44(A)) would indicate that the change from the temperature when the PVC was install would need to greater than +/- 60F (2.43in/100') to require expansion fittings.
IMHO you would need to install the PVC on the coldest or hottest day of the year to necesitate the use of expansion fittings in every section.
352.44 indicates that expansion fitting are only required if the expected change in length in straight runs between fixed items is 0.25 in. or greater.
In a 10' section of PVC (352.44(A)) would indicate that the change from the temperature when the PVC was install would need to greater than +/- 60F (2.43in/100') to require expansion fittings.
IMHO you would need to install the PVC on the coldest or hottest day of the year to necesitate the use of expansion fittings in every section.
- Location
- Illinois
- Occupation
- retired electrician
Re: PVC expansion fittings
Sam,
The temperature at the time of installation has no impact on the need to install expansion fitting. The installation temperature only is used for the setting of the expansion fitting piston. If the calculated change in length exceeds 1/4" for the temperature between the hottest and coldest expected exposure temperature an expansion fitting is required. See the NEMA installation guide for expansion joints in PVC conduit.
Don
[ May 19, 2004, 11:20 AM: Message edited by: don_resqcapt19 ]
Sam,
The temperature at the time of installation has no impact on the need to install expansion fitting. The installation temperature only is used for the setting of the expansion fitting piston. If the calculated change in length exceeds 1/4" for the temperature between the hottest and coldest expected exposure temperature an expansion fitting is required. See the NEMA installation guide for expansion joints in PVC conduit.
Don
[ May 19, 2004, 11:20 AM: Message edited by: don_resqcapt19 ]
wanderer20001us
Senior Member
Re: PVC expansion fittings
I stand corrected.
I stand corrected.
springtownspark
Member
Re: PVC expansion fittings
I worked for a contractor breifly that had been a maintenance electrician that started his own business. He got a job hooking up AC units that involved running about 150' of 1" PVC. He didn't have the appropriate supports for the 1" and he wouldn't go to True Value and pay their price for straps or mini's. My preferred method would've been 1-1/4" mini's left loose on the conduit. "We'll come back and catch it later". He wouldn't listen to any advise about expansion or what that run of PVC would look like later. That was in the springtime in eastern KS. About July the church was complaining about how bad that run of conduit looked down the side (parking lot side) of their building a foot off the ground with a one hole strap every thirty to forty feet. That stuff would've made a good run for a roller coaster. He sent me back over to straighten up the mess. "I know I should've listened but go fix it please" In short there was no "fix" to that mess. I was aware of section 347-9 but even I had no idea PVC would move that much. Sorry about rambling on with this story but to me it brought a good question to my mind. IF PVC will move that much, think about the conductors inside.
I worked for a contractor breifly that had been a maintenance electrician that started his own business. He got a job hooking up AC units that involved running about 150' of 1" PVC. He didn't have the appropriate supports for the 1" and he wouldn't go to True Value and pay their price for straps or mini's. My preferred method would've been 1-1/4" mini's left loose on the conduit. "We'll come back and catch it later". He wouldn't listen to any advise about expansion or what that run of PVC would look like later. That was in the springtime in eastern KS. About July the church was complaining about how bad that run of conduit looked down the side (parking lot side) of their building a foot off the ground with a one hole strap every thirty to forty feet. That stuff would've made a good run for a roller coaster. He sent me back over to straighten up the mess. "I know I should've listened but go fix it please" In short there was no "fix" to that mess. I was aware of section 347-9 but even I had no idea PVC would move that much. Sorry about rambling on with this story but to me it brought a good question to my mind. IF PVC will move that much, think about the conductors inside.
- Location
- Bremerton, Washington
- Occupation
- Master Electrician
Re: PVC expansion fittings
Here is another aspect of PVC installation:
A contactor was installing underground runs of 2" PVC. It was a hot day (80's), well hot for the Pacific NW. The PVC was strung out on the edge of the ditch, then installed and backfilled. The cooler earth (52 deg F) caused the PVC to contract and pull apart at the joints. Since this was a government job, the PVC had to be dug up every 20 ft and repaired at the joints.
In my opinon, PVC should never be run on the exterior of a building, its OK for service going up to a weatherhead where it can move away from the meter. Now that we have at least two manufacturers with listed raintight EMT fittings, EMT would be a preferred alternative.
Here is another aspect of PVC installation:
A contactor was installing underground runs of 2" PVC. It was a hot day (80's), well hot for the Pacific NW. The PVC was strung out on the edge of the ditch, then installed and backfilled. The cooler earth (52 deg F) caused the PVC to contract and pull apart at the joints. Since this was a government job, the PVC had to be dug up every 20 ft and repaired at the joints.
In my opinon, PVC should never be run on the exterior of a building, its OK for service going up to a weatherhead where it can move away from the meter. Now that we have at least two manufacturers with listed raintight EMT fittings, EMT would be a preferred alternative.
springtownspark
Member
Re: PVC expansion fittings
I agree with you 100% Tom. I had an inspector turn down a service I ran in EMT. Said it would leak. I tried pointing out the fittings were raintight,(only one really mattered as it entered the top of an LB)the fittings were listed and approved. The AHJ told me he didn't care he preferred PVC, that's what he wanted. Personally I think it looks like cheap junk on a building. I showed the home owner where EMT is accepted in the NEC but would not argue with the inspector anymore. I felt that home owner suddenly questioned my qualifications. Same inspector told me I needed to run "pipe" for the wiring in a building downtown but allowed a carpenter/handyman to wire the offices in romex. Think it's personal ? I do. I have considered asking him for credentials to inspect my work. I guess I'm just to assume he is qualified? Just a thought ! I fight with myself everyday it seems for the best way to deal with this small town good 'ole boy syndrome. Truth is I'll never fit in with these boys and don't want to. I thought there was an article 90-?? something to the effect the inspector didn't have the right to make up his own rules. Perhaps there never was such an article, perhaps long since deleted. Any help out there? I've always felt it was better to just do what an inspector asked. Not to make waves or they would be picking on everything you do. Especially this one. Part time cop & dog catcher. I feel he definitely has the power to make my life miserable.
Thanks, Dan
I agree with you 100% Tom. I had an inspector turn down a service I ran in EMT. Said it would leak. I tried pointing out the fittings were raintight,(only one really mattered as it entered the top of an LB)the fittings were listed and approved. The AHJ told me he didn't care he preferred PVC, that's what he wanted. Personally I think it looks like cheap junk on a building. I showed the home owner where EMT is accepted in the NEC but would not argue with the inspector anymore. I felt that home owner suddenly questioned my qualifications. Same inspector told me I needed to run "pipe" for the wiring in a building downtown but allowed a carpenter/handyman to wire the offices in romex. Think it's personal ? I do. I have considered asking him for credentials to inspect my work. I guess I'm just to assume he is qualified? Just a thought ! I fight with myself everyday it seems for the best way to deal with this small town good 'ole boy syndrome. Truth is I'll never fit in with these boys and don't want to. I thought there was an article 90-?? something to the effect the inspector didn't have the right to make up his own rules. Perhaps there never was such an article, perhaps long since deleted. Any help out there? I've always felt it was better to just do what an inspector asked. Not to make waves or they would be picking on everything you do. Especially this one. Part time cop & dog catcher. I feel he definitely has the power to make my life miserable.
Thanks, Dan
tonyi
Senior Member
Re: PVC expansion fittings
Excellent point - copper is a lot more dimensionally stable than the PVC. Proper use of expansion fittings eliminates the problem, but not using them could result in lugs and terminations really getting cranked on as a long lengths of plastic heats up and expands. If someone didn't use the fittings, they probably didn't leave much slop at the ends either...
caosesvida
Senior Member
Re: PVC expansion fittings
I agree pvc on the outside of a building does end up looking bad sooner or later, and I have seen many cases of the conduit broken in cold weather on impact. Its scary looking on a 400 amp service on a sidewalk (beach town) and the conductors are there for every kid to stick something in the big holes in the conduit. I have been using rigid, always a nice looking job, and lasts forever, except maybe for a little rust. Have seen lots of fire alram and computer guys use pvc without expansion joints, man what a mess, pulled apart two inches in some places. You would think the fire marshal would get on that.
I agree pvc on the outside of a building does end up looking bad sooner or later, and I have seen many cases of the conduit broken in cold weather on impact. Its scary looking on a 400 amp service on a sidewalk (beach town) and the conductors are there for every kid to stick something in the big holes in the conduit. I have been using rigid, always a nice looking job, and lasts forever, except maybe for a little rust. Have seen lots of fire alram and computer guys use pvc without expansion joints, man what a mess, pulled apart two inches in some places. You would think the fire marshal would get on that.
Re: PVC expansion fittings
Thanks for the reply's. I've asked three local inspectors and they do not feel as strongly as the AHJ that requires an expansion fitting in a short run of conduit. I will be installing them on Monday to pass this inspection. But I will be talking to the board there after to get some kind of ruling. For this guy a 10' stick of conduit needs a fitting. Carlon representives have given me a letter indicating where the fitting was design to be used, but he wouldn't accept the letter. This was 3 years ago or so. It's the price you pay I guess to try and make a living.
Thanks for the reply's. I've asked three local inspectors and they do not feel as strongly as the AHJ that requires an expansion fitting in a short run of conduit. I will be installing them on Monday to pass this inspection. But I will be talking to the board there after to get some kind of ruling. For this guy a 10' stick of conduit needs a fitting. Carlon representives have given me a letter indicating where the fitting was design to be used, but he wouldn't accept the letter. This was 3 years ago or so. It's the price you pay I guess to try and make a living.
springtownspark
Member
Re: PVC expansion fittings
I thought someone might have replied to my comment about inspectors making their own rules.
For some reason Art. 90-4 came to my mind, Enforcement. I looked back through many editions of the NEC but could find nothing partaining other than inspectors could waive requirments in their judgement. Sorry guys, as bad as it probably sounds I really thought there was something there. I'm not convinced PVC is a good method to use on the exterior of a building. In my own judgement a service built with a 2" GRC mast, meter base with EMT entering an LB is a better method than useing PVC into a PVC LB. PVC is listed sunlight resistant but I'm not convinced the sun and weather do not break it down and make it more brittle. I too have seen a lot of it that appears to have broken in cold weather. I really do think it looks like cheap plastic junk. Even worse if installed on a metal building. Just my oppinion and I do know what those are like. Thanks, Dan
I thought someone might have replied to my comment about inspectors making their own rules.
For some reason Art. 90-4 came to my mind, Enforcement. I looked back through many editions of the NEC but could find nothing partaining other than inspectors could waive requirments in their judgement. Sorry guys, as bad as it probably sounds I really thought there was something there. I'm not convinced PVC is a good method to use on the exterior of a building. In my own judgement a service built with a 2" GRC mast, meter base with EMT entering an LB is a better method than useing PVC into a PVC LB. PVC is listed sunlight resistant but I'm not convinced the sun and weather do not break it down and make it more brittle. I too have seen a lot of it that appears to have broken in cold weather. I really do think it looks like cheap plastic junk. Even worse if installed on a metal building. Just my oppinion and I do know what those are like. Thanks, Dan
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