Methods for securing rigid conduit nipple penetration thru rim joist

S

solarken

NABCEP PVIP
Location
Hudson, OH, USA
Occupation
Solar Design and Installation Professional
This is a common situation for me with buried PVC conduit from yard coming to house, rising thru elbow thru expansion fitting and into a metal LB where I transition to metallic conduit for entry in the house. The LB has PVC downward from the buried conduit, and a 6 inch rigid nipple horizontally thru the siding and rim joist into the basement ceiling cavity. Securing the LB from the outside is a bit clunky: The expansion coupling gets in the way, there is not a lot of room above it for the clamp, there is the siding to block/concrete foundation transition there, and the PVC is flexible so it moves quite a bit when pulling wire. On the inside, there is the nipple extending thru the middle of a typical 2x12 rim joist into a joist cavity. It is easiest to use a short piece of FMC to transition from the rigid to EMT and then onto the equipment, so the FMC provides no support. Does anyone make a clamp that can secure Rigid that penetrates 2x lumber at 90 degree angle? Usually it is 3/4 or 1 inch.
 
What is the distance between the bottom of the LB and the ground? You can't get a strap somewhere in there with a screw into the siding or foundation? Move the expansion coupling down. Use a piece of strut? Really, the clamp belongs on the outside below the LB.

For grabbing the nipple inside, you are going to have to get creative. One idea is a 2x4 block screwed to the rim joist right next to the nipple, then use a one hole strap to secure the nipple to the block.

-Hal
 
This is a plumbing strap for 1" CTS, which would probably fit 3/4" RMC, but perhaps using a plastic plumbing strap is not OK. I guess you'd like a similar metal part made for RMC.

Cheers, Wayne

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hbiss said:
What is the distance between the bottom of the LB and the ground? You can't get a strap somewhere in there with a screw into the siding or foundation? Move the expansion coupling down. Use a piece of strut? Really, the clamp belongs on the outside below the LB.

For grabbing the nipple inside, you are going to have to get creative. One idea is a 2x4 block screwed to the rim joist right next to the nipple, then use a one hole strap to secure the nipple to the block.

-Hal
Click to expand...
In this most recent install that has vinyl siding, I used a small siding mount block (MM7 made by Arlington) for the LB penetration as well as to mount a receptacle box next to it for an outlet I am also running to the array in the yard. The LB drops below the block so I can't attach there, and then I had to put an offset bend in it to get from the plane of the block to the plane of the concrete block foundation, so there is a little distance there. I can put a strap to the foundation at that point but it does not seem like it will hold the LB tight to the block during the pull. I like your idea of the wood block on the inside, may try that.
 
On the inside a longer nipple with a 2 x 4 between the joists with a strap or strut between the joists with a clamp. If it is secured well inside and the expansion joint is taking up all the room outside then a screw through the LB may be the only choice even though I don't care for that do to water entry possibility. If the pipe outside is that short and it is secured inside well do you need a support outside.?
 
OldBroadcastTech said:
or these
www.ebay.com

25mm 30mm 35mm 40mm Capacitor Clip Clamp Capacitor Mounting Buckle | eBay

L Quantity & Types (Optional): 5 x 25mm Capacitor Clip, 5 x 30mm Capacitor Clip, 5 x 35mm Capacitor Clip, 5 x 40mm Capacitor Clip, 10 x 25mm Capacitor Clip, 10 x 30mm Capacitor Clip, 10 x 35mm Capacitor Clip, 10 x 40mm Capacitor Clip.
www.ebay.com
Click to expand...
If you can find one of the needed size. An inspector would be scratching his head over what that is. I know and you know, but I wouldn't use something that isn't standard to our industry.

-Hal
 
Depending on your nipple and joist location, you may be able to utilize a minerallic clamp bolted to a steel right angle bracket, or a piece of angle iron. Could be made plenty sturdy.
 
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