ptonsparky
Tom
- Occupation
- EC - retired
Will that added strap do anything for the installation that isn‘t already done by the expansion join? Other than make the inspector happy?
Underground conduits emerging above ground – securing required
- Thread starter stevenje
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....Yes, in fact it will, it will stop it from pulling away from the box/panel knockout, and also keep centered to box/panel knockout by stopping it from going left or right. The conduit can only go up or down, that’s where the expansion fitting comes into play.
Carultch
Senior Member
- Location
- Massachusetts
Just be sure to strap it above the upper part of the expansion joint, otherwise you defeat the entire purpose of the expansion joint, if you rigidly strap it below the expansion fitting. I've seen that as a common mistake, when the installer doesn't connect the dots in their understanding of how the components work.
It's unfortunate that the expansion joint outer diameters aren't indexed to the OD of the next size up conduit, as an industry standard. That way you could strap the upper portion of the expansion fitting. You'd have to use adjustable straps like pipe hanger clamps to secure conduit on the expansion fitting, but strut straps aren't going to work.
kwired
Electron manager
- Location
- NE Nebraska
- Occupation
- EC
Why?
Strut and clamps are made for securing more than just electrical raceways and there are many sizes of clamps out there that may not be standard raceway sizes. Electrical supply house may only have clamps that correspond to standard raceways as a general rule.
Carultch
Senior Member
- Location
- Massachusetts
I'm not talking about securing the conduit in general, I'm talking about securing the upper body (barrel) of the expansion joint specifically. If you can find a strap that fits the barrel, you can do this, but good luck finding one. It would likely be one that is adjustable, rather one that is built to a specific size.
Consider a 2" expansion joint. Next size up conduit is nominal 2.5", with an actual OD of 2.875". The barrel of a 2" expansion fitting has a clearance fit in straps made for a 2.875" OD raceway, and will not be secured. I've seen improvised solutions with mixed of strut straps of adjacent sizes to make this work.
kwired
Electron manager
- Location
- NE Nebraska
- Occupation
- EC
How tight of a fit does it need to be? Strut or other saddle type clamps by nature do have a little range to them even if marked for a specific pipe/tube.
1 hole and 2 hole straps are fixed size, straps intended for PVC generally have a certain amount of extra room to allow for expansion/contraction and are not a tight fit to begin with, placement on an uneven surface may allow them to pull up pretty tight or in some cases leave the fit pretty loose.
Dirt is not a fitting.
there are also comments about expansion fittings, the OP never mentions the use of expansion fittings, or ground movement. I think we have all seen inspectors that just need to find anything wrong, even if it is not wrong.
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