What went wrong with fastening these conduits?

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lbeachmike said:
Thanks for all the responses.

This is concrete-based stucco. There is no foam here.

I read that friction-fit fasteners should be used in this application to allow for expansion/contraction. Is this similar to what you guys are describing?

Aren't there specific code requirements for how this should be done?
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No, what they are describing is expansion joints in the PVC conduit, and the straps need to hold the pipe loosely enough so that the PVC can slide in the straps as it expands and contracts. Yes, there are tables in the NEC for calculating how many joints are needed and where they need to be placed. Also, you'd need to allow for some movement in the wire when the conduit moves.

But I agree with whoever said that it should have been metal conduit instead of plastic.
 
lbeachmike said:
Thanks for all the responses.

This is concrete-based stucco. There is no foam here.

I read that friction-fit fasteners should be used in this application to allow for expansion/contraction. Is this similar to what you guys are describing?

Aren't there specific code requirements for how this should be done?
Click to expand...

Look up Carlon E945E that is a 3/4" expansion fitting as we are referring to.
 
Thanks for all the info.

I don't expect that my electrician is going to be interested in replacing the PVC with metal conduit. It sounds like metal would be better for such a long run because of its rigidity and lack of expansion/contraction?

Can anybody help in terms of what is a satisfactory way to remedy the existing set of circumstances? Is there an example of which type of clamp should be used?

Is it possible that metal conduit is not the choice product here because of proximity to the ocean? Any outdoor metal tends to rust quickly where I live. Both electricians I used ran outdoor PVC conduit, and my new house also has outdoor PVC conduit fastened snugly to brick with metal clamps and metal anchors - has been there for several years and all is perfect there.

Perhaps it was the original plastic clamps and plastic anchors that suffer from the expansion/contraction issue, hence why they don't seem to hold up.
 
lbeachmike said:
Thanks for all the info.

I don't expect that my electrician is going to be interested in replacing the PVC with metal conduit. It sounds like metal would be better for such a long run because of its rigidity and lack of expansion/contraction?

Can anybody help in terms of what is a satisfactory way to remedy the existing set of circumstances? Is there an example of which type of clamp should be used?

Is it possible that metal conduit is not the choice product here because of proximity to the ocean? Any outdoor metal tends to rust quickly where I live. Both electricians I used ran outdoor PVC conduit, and my new house also has outdoor PVC conduit fastened snugly to brick with metal clamps and metal anchors - has been there for several years and all is perfect there.

Perhaps it was the original plastic clamps and plastic anchors that suffer from the expansion/contraction issue, hence why they don't seem to hold up.
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It's not a clamp expansion/contraction or conduit weight issue. I'd use metal clamps (and more of them - every 3' max) and it that doesnt fix the issue, then you're going to need expansion joints. Someone several posts up mentioned intentional damage/someone climbing on the conduit - could be.
 
JFletcher said:
It's not a clamp expansion/contraction or conduit weight issue. I'd use metal clamps (and more of them - every 3' max) and it that doesnt fix the issue, then you're going to need expansion joints. Someone several posts up mentioned intentional damage/someone climbing on the conduit - could be.
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Nobody is climbing on the conduit. You can rule out that theory.
 
doesnt look to be stucco over block. looks like wire meshed foam covered by stucco. the use of mollies was wrong, should have used a longer screw, which may be a masonry hex head tapcon, or maybe a wood screw, depending on what the base of that wall is. not everywhere has code that requires the full shell to be sheathed, etc.

plus, expansion needs to be accounted for. i see 2 strikes with that install.

are those panels also just mollied in too?

any reason why it was not trenched in that dirt ??
 
lbeachmike said:
Nobody is climbing on the conduit. You can rule out that theory.
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Sorry we are giving you the run around. Summarize my opinion and what seems to be the opinion of others. Install Listed expansion fittings as required to comply with NEC code section 352.44. Can't be more specific because this depends on the temperature change in your area, but a reasonable guess is one 8" expansion fitting for each conduit would be adequate. Use metal anchors at a distance of no more than 3 feet apart, that are anchored at least well enough that you can't pull them out or loosen them up by grabbing the anchor with your hand. YOu may want to tell them to use hot dip galvanized straps to avoid rusting in the salt air.

Hope this helps.
 
FionaZuppa said:
doesnt look to be stucco over block. looks like wire meshed foam covered by stucco. the use of mollies was wrong, should have used a longer screw, which may be a masonry hex head tapcon, or maybe a wood screw, depending on what the base of that wall is. not everywhere has code that requires the full shell to be sheathed, etc.

plus, expansion needs to be accounted for. i see 2 strikes with that install.

are those panels also just mollied in too?

any reason why it was not trenched in that dirt ??
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It was not trenched because we live in a flood zone, and because the cost would be significantly higher. I would have never expected it to be a significant challenge to mount conduit to a wall. Isn't this done successfully all the time? By the way, it's not foam. It's a 1920 building. Underneath the outer thin stucco layer appears to be another layer of concrete stucco or some sort of masonry. The guys who did the job would have known precisely what was there because they jackhammered that large hole through the wall that you see patched in the photo. So they got to see precisely every layer of that wall.
 
Strathead said:
Sorry we are giving you the run around. Summarize my opinion and what seems to be the opinion of others. Install Listed expansion fittings as required to comply with NEC code section 352.44. Can't be more specific because this depends on the temperature change in your area, but a reasonable guess is one 8" expansion fitting for each conduit would be adequate. Use metal anchors at a distance of no more than 3 feet apart, that are anchored at least well enough that you can't pull them out or loosen them up by grabbing the anchor with your hand. YOu may want to tell them to use hot dip galvanized straps to avoid rusting in the salt air.

Hope this helps.
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Strathead - THANK YOU! I most definitely appreciate all of the thoughts and opinions offered on this thread. Your summarized details is precisely the kind of info I was hoping for.

Questions:

1. If this is not compliant with NEC code, how was the electrician able to get a "Certificate of Compliance" for this work?

2. Re: temps - This is in Long Beach, NY - summers reach into the 90s, though generally 80s and winters in recent years are usually in the 40s but will dip below to 20s or very rarely below that. When you speak of the "temperature change" in my area - are you referring to what I just provided, or to the extent of temperature swings within a given day or week?

Thanks.

Mike
 
Whole year. You need to know the change in length between the shortest the pipe will be and the longest the pipe will be.
If it was installed at less than full expansion it will tend to buckle to take up the additional length.
If it was installed at less than full contraction it can pull ends or even joints lose when it shrinks.
 
lbeachmike said:
1. If this is not compliant with NEC code, how was the electrician able to get a "Certificate of Compliance" for this work?
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When an inspector inspects a job like this they don't do a stress test on the anchors and straps.

It's a visual inspection and this job probably met code requirements. These are listed straps and if the required number were used it would have appeared to be OK. Not only that but the job probably looked fine when the inspector saw it.
 
lbeachmike said:
It was not trenched because we live in a flood zone, and because the cost would be significantly higher.
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You really think those conductors get any wetter than normal during a flood ( gets pretty wet down there during a rain) and you are not making taps or splices down there. The conductors would need to be rated for wet location anyway.

Cost is normally what it always boils down to.
 
lbeachmike said:
Strathead - THANK YOU! I most definitely appreciate all of the thoughts and opinions offered on this thread. Your summarized details is precisely the kind of info I was hoping for.

Questions:

1. If this is not compliant with NEC code, how was the electrician able to get a "Certificate of Compliance" for this work?

2. Re: temps - This is in Long Beach, NY - summers reach into the 90s, though generally 80s and winters in recent years are usually in the 40s but will dip below to 20s or very rarely below that. When you speak of the "temperature change" in my area - are you referring to what I just provided, or to the extent of temperature swings within a given day or week?

Thanks.

Mike
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In my experience the inspectors don't enforce the expansion of PVC aggressively. I was surprised when I first did the calculation for Florida and figured out that any straight run over 10 feet requires an expansion fitting and that is without figuring in the historical high and low.

You second question, is sort of dependent on what you are trying to achieve and the inspection department, but I would use the high and the low as you spelled them out. mid to high 90's and 20 for a swing of 78 degrees F which is 3.24" per 100 feet and code requires a fitting for over 1/4" of expansion. Which work out to about 8 feet before a fitting is needed.
 
If your run is 40 feet long and your temperature extremes are 100F degrees that PVC is about 1-5/8" longer at the upper extreme then it is at the lower extreme. With no expansion fittings that is going to put some strain on components, when plastic straps like you have are used those are usually about the first thing that goes.

Metal raceways also expand and contract with temperature change, and even the building does, but not anywhere near the same rate as the PVC does.
 
lbeachmike said:
It was not trenched because we live in a flood zone, and because the cost would be significantly higher. I would have never expected it to be a significant challenge to mount conduit to a wall. Isn't this done successfully all the time? By the way, it's not foam. It's a 1920 building. Underneath the outer thin stucco layer appears to be another layer of concrete stucco or some sort of masonry. The guys who did the job would have known precisely what was there because they jackhammered that large hole through the wall that you see patched in the photo. So they got to see precisely every layer of that wall.
Click to expand...

stucco over what, block? the use of plastic molly is wrong, that plastic is too soft. the use of a concrete screw, like tapcon masonry screws, is what should be used there. i myself might have even used a small amount of jb weld on each screw depending on how the stucco/block condition was.

my hypothesis, if the correct screws were used they would have stayed in, and only the loops would have broken.

lesson learned for whoever installed that.
 
kwired said:
If your run is 40 feet long and your temperature extremes are 100F degrees that PVC is about 1-5/8" longer at the upper extreme then it is at the lower extreme. With no expansion fittings that is going to put some strain on components, when plastic straps like you have are used those are usually about the first thing that goes.

Metal raceways also expand and contract with temperature change, and even the building does, but not anywhere near the same rate as the PVC does.
Click to expand...

My code book says 100 degree F is a 4.06 inch change per 100 feet
 
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