Making multiple 90 degree bends

[Mattula]

When installing multiple conduits on a rack.....eventually you have to bend some 90's. I know that in order to keep the proper spacing you must add the conduit diameter and the center to center spacing in order to keep the conduits in the proper spacing........but how can you lay out your marks so the far end line up..........so you dont have to cut the condiuts to line up?

 

[infinity]

You can't line up both ends without cutting. The inner conduits will always end up longer than the outer ones. For example if (4)-4" EMT's , spaced 1.5" apart, came out of a box and 90'd, the first elbow is say 30", the next would be about 36" the next about 42" and the last 48". If all the conduits were 10' long at the start each conduit would be 6" shorter than the one adjacent to it on the end opposite of the elbows. If you wanted the ends to line up you have to cut three of the conduits.

 

[e57]

Why make them all line up? It wastes material. And I think its rather cool when you bend the other way and they all line up again, otherwise they stagger your spacing distance (Not too much anyway.) and look just as acceptable to me. Also easier to count off distance with full 10's.

 

[infinity]

One major advantage of lining the couplings up is that the couplings are less likely to fall out on a rack. We usually install our racks first and then lay the conduit on it. A large row of conduits is almost guaranteed to end up with some of the couplings on the racks which interferes with installing the straps. And for those who are very anal, IMO the couplings lined up simply looks better.

 

[Rockyd]

Unless your being paid to have couplings all line up (kissing couplings) it's a waste of time and material. If a client wants it, no problem, we can do it that for you. Remember, about the only place you get to hide "error" in concentric bending is in the ends... A good bender (triple nickel or 884) and a craftsman can cut, thread, and bend the pipe, not bend, cut, and thread their pipe.

 

[iwire]

We sometimes get job specifications that prohibit lining up the couplings. This can be a pain with pipe racks for the reasons Trevor mentioned.

 

[infinity]

We sometimes get job specifications that prohibit lining up the couplings. This can be a pain with pipe racks for the reasons Trevor mentioned.

Why would they prohibit this? Strength?

 

[iwire]

Why would they prohibit this? Strength?

I can only assume so.

The last time was last summer, I had a duct bank I had to extend that had 12 - 4" PVCs in two layers of six, concrete encased with rebar as well.

Same job I had a parallel run of 5 - 3" EMTs on trapeze racks that also had to be staggered.

On that it was just as well as the specs called for compression fittings and I had so little space the staggered couplings made it easer to get a strap wrench on....until we got to box connectors.