What went wrong with fastening these conduits?

Status
Not open for further replies.
kwired said:
Yes, that is .406 for every 10 feet and 40 feet would be just about 1-5/8".
Click to expand...
pvc is 3.6" per 100ft @ 100F diff
or 0.036" per ft

40ft is just about 1.44" @ 100F diff

~1.44 to ~1.625, sounds about right.

that expansion has to go somewhere, and if the end points of a round tube do not flex the tube will bow, and a bow from ~1.5" linear expansion will be pretty good.
 
GoldDigger said:
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.
Click to expand...

Gee, the news on this keeps getting better and better :weeping: This installation was done in February of this year.
 
growler said:
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.
Click to expand...

Then I suppose it may have been cost, though I'm not sure the option of burying the conduits was even discussed. I had three electricians look at it, and nobody suggested trenching it. In fact, all three suggested the opposite. I suppose they were all seeking to minimize the scope of work and/or the cost to me. Long Beach, NY still has tons of houses under construction since Sandy hit here. As such, contractors are spread thin and quality has gone down. Most guys are rushed to get in and out. I used a reputable licensed guy who has done work in this town for over a decade and has a good local reputation. I was very surprised by the outcome because these details seem to be very basic.
 
growler said:
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.
Click to expand...

But no expansion joint was used as you guys are emphasizing is required. Why would the inspection not pick up on that if it is a code requirement?
 
FionaZuppa said:
pvc is 3.6" per 100ft @ 100F diff
or 0.036" per ft

40ft is just about 1.44" @ 100F diff

~1.44 to ~1.625, sounds about right.

that expansion has to go somewhere, and if the end points of a round tube do not flex the tube will bow, and a bow from ~1.5" linear expansion will be pretty good.
Click to expand...

Thanks again for all of the details - this is extremely helpful.

Is it a simple matter to add the expansion fitting? It seems that it would not be because doesn't everything have to be disconnected and re-pulled through the conduit? Where does the expansion fitting need to get added? Anywhere along that 30-40 foot run?
 
The shortest maximum range of travel for all points on the length of the pipe will occur when the expansion fitting is in the center of the run. That can make things a little less stressful for the straps, etc.
 
lbeachmike said:
Gee, the news on this keeps getting better and better :weeping: This installation was done in February of this year.
Click to expand...

Was it -10*F that day? Even an 80* day now would give 90* of all expansion. If it had been installed on a 45* day, it might not have popped the clamps with some expansion and contraction

Even if you strap it with steel, it's still going to be bowed all to heck. and before you ask, no, I dont think anyone makes a two-piece (slip on/in) expansion joint for 'after the fact' (wire is run). You'll have to pull it back out.

I do not know why the expansion fitting was overlooked by them or the inspector. Best to add it in the middle, and in a way so that you take into account ambient temp: if it's put in on a 95* day, you're going to have all contraction... -10*, all expansion.
 
lbeachmike said:
Thanks again for all of the details - this is extremely helpful.

Is it a simple matter to add the expansion fitting? It seems that it would not be because doesn't everything have to be disconnected and re-pulled through the conduit? Where does the expansion fitting need to get added? Anywhere along that 30-40 foot run?
Click to expand...

Yes, you'll have to pull the wire out to put in expansion joints. It looks to me like those PVC pipes are toast, anyway. I'll bet you'd never get them looking straight again.
 
ggunn said:
Yes, you'll have to pull the wire out to put in expansion joints. It looks to me like those PVC pipes are toast, anyway. I'll bet you'd never get them looking straight again.
Click to expand...

If it's a south facing wall, PVC will always look like limp noodles after the first summer.
 
That will always look like crap, even with expansion fittings and better clips unless you clip it every two feet. That should have went in the ground or use a main breaker meter socket and run the wire inside.
 
gadfly56 said:
If it's a south facing wall, PVC will always look like limp noodles after the first summer.
Click to expand...

Fortunately it's not a south-facing wall. It's actually west-facing and entirely shadowed by the neighboring house, so it doesn't get much (if any) direct sunlight.

I measured it today and it's just over 30 feet. Grabbed some updated and additional photos that I'll post tomorrow.

Limp noodles ... nice.
 
lbeachmike said:
But no expansion joint was used as you guys are emphasizing is required. Why would the inspection not pick up on that if it is a code requirement?
Click to expand...

As I mentioned earlier, in my experience I rarely see expansion fittings installed in PVC runs. Non-Residential contractors generally don't install PVC above ground with the exception of short pieces stubbed up or between pieces of equipment, so we don't pay a lot of attention to the expansion requirements. For me and many others the biggest reason we don't is that it will always sag in the sunlight. even with allowance to expand, it is going to sag when it gets hot, so it will not look professional. It is like using factory bent elbows on 1/2" EMT. Self respecting electricians won't use them.

Residential is different. The entire tooling, experience, training and cost approach is not conducive to bending and installing metal conduit. This isn't a judgement. Residential electricians work is different that doesn't mean inferior.

I have done a couple of commercial greenhouses. Design build. I used PVC extensively for the first time and as such, I researched its installation. That is when I discovered to my surprise I couldn't run 10 feet without an expansion fitting. I just don't think it has come across the radar of most inspectors, just like it hasn't come across the radar of most electricians. Heck in the 90's we used to put as many wires as we could fit in a conduit. Electricians and inspectors both ignored the entire requirement to be concerned about heating from to many amps in the wires. Then inspectors and electricians both started paying attention and now you wouldn't dare violate that code.

When we did that first greenhouse, my journeyman came back to me after installation and exclaimed that he first thought I was being ridiculous, but he installed the PVC in the afternoon, and when he went there the next morning the fittings had shortened over 3". He was sold.
 
post #54, so that begs the question, why not aluminum (near water) or steel on the wall, or pvc in the ground? if on the wall i would have done that in steel and would have paint "matched" it to the wall to make it a professionally done install.

for many reasons as stated, looks like (literally) failures in many areas of that install.

so whats the fix? likely pull back some wires, add expansion fitting, pull wires back in, secure it better.

as for UV and PVC, simple, get some plastic primer, then spray acrylic color over that.
 
Note the lack of offset bends or connectors at the panel. There was significant stress on those anchors.

Either make an offset bend somehow or put a block under the clamp to make of the gap width. You will also have to extend the ell out.
 
Status
Not open for further replies.
Top