Strut Span

[Alwayslearningelec]

What the longest span you've even done for a trapeze rack? I've seen up to 6'.

For longer spans would you use 1-5/8 strut, taller or back to back? Thanks

 

[infinity]

It depends on the size and type of conduit and what's in it. With 1 5/8" strut and 1" EMT you could probably go 10'. With 4" RMC and 750 kcmil copper conductors maybe 3'. Also you can go with longer lengths you may just need intermediate supports.

 

[Alwayslearningelec]

It depends on the size and type of conduit and what's in it. With 1 5/8" strut and 1" EMT you could probably go 10'. With 4" RMC and 750 kcmil copper conductors maybe 3'. Also you can go with longer lengths you may just need intermediate supports.

You use larger strut than 1-5/8" ever for trapeze?

 

[infinity]

You use larger strut than 1-5/8" ever for trapeze?

Sure we may use 3" for long spans where there is nothing above to hang off of or if were spanning a wide piece of duct work.

 

[don_resqcapt19]

You use larger strut than 1-5/8" ever for trapeze?

Yes, often use the 2 7/16" or 3 1/4" deep for long spans. A few times we ordered 20' lengths, and often that was 3 1/4" and double wide.

Typically anything over 5 or 6' would have intermediate supports.

If we were designing our own, we would use the technical data in the B-Line Strut catalog.

 

[Alwayslearningelec]

Thank you guys

 

[garbo]

What the longest span you've even done for a trapeze rack? I've seen up to 6'.

For longer spans would you use 1-5/8 strut, taller or back to back? Thanks

Years ago we ran 13' long back to back 15/8 " unistrut for only four 3/4" conduits. Ceiling was 20' High but had three 4' by 4' duct side by side and we could not get a 1/2" piece of all thread in between on ducts. Large supply house that we used had over 12 branches and was able to supply us with 15/8" 20' unistrut a lot quicker then the 3.25" deep strut. We keep conduit maybe 3' from the end of long strut so not to create a sag.

 

[don_resqcapt19]

Years ago we ran 13' long back to back 15/8 " unistrut for only four 3/4" conduits. Ceiling was 20' High but had three 4' by 4' duct side by side and we could not get a 1/2" piece of all thread in between on ducts. Large supply house that we used had over 12 branches and was able to supply us with 15/8" 20' unistrut a lot quicker then the 3.25" deep strut. We keep conduit maybe 3' from the end of long strut so not to create a sag.

I was surprised to see that the 3 1/4" has more strength as a beam than the back to back 1 5/8". I would have thought that the "U" bends at the top and bottom of back to back would give it more strength.

 

[Eddie702]

Have seen strut way overloaded when supporting air handlers, sagging but never broken. I agree the strut catalogs have loading information. I doubt many look it up.