Optimizing Conduit Bending for Wire Pulling Efficiency

[ISX]

Pertaining to conduit bending and ease to pull wire, would it be easier through one 90 degree bend of a set radius, or would it be easier to pull through two 45 degree bends using the same radius. The 45's could be any distance apart from each other, I don't think it would matter too much (am I wrong?). If they each have the same radius and each ends up being 90* bend then the total arc length would be the same for both so theoretically they would be the same difficulty pulling wire through. It would be one thing if it was a right angle that the wire creased upon and snagged but obviously on a radius it doesn't happen. So which way would be easiest and why? Would three 30 degree angles be even easier to pull through?

 

[Averagesupernova]

Technically multiples less than 90 degrees that total 90 degrees should be harder to pull than a single 90. The reason is that the wire has to continously bend as it is pulled around the corner. So it bends around a 45, then straightens out, then a few feet later bends again. Isn't it easier to get a radius established and then allow it to go all the way around a 90 instead of bending twice? That's my hypothesis, not necessarily fact.

 

[LeroyLaRey]

it depends on the radius of the bend, standard plastic electrical conduit provides a lot of wide sweep elbows, or you could use a piece of flexible conduit for a really wide bend (like 5 foot radius). multi-filament wire might be easier to pull too.

:)

 

[ISX]

I am saying if the radius is the same on both the 90 and the 45's. I know a bigger radius helps but I am trying to find an answer for the parameters I set forth. The wire bending hypothesis makes a lot of sense, but how hard is it to bend 14 ga wire? I can see it on big wire but let's just say its 14ga and I have a lot of them in the conduit.

 

[Averagesupernova]

You said it yourself. You have a lot of them in the conduit. I didn't say it would be noticeable. I just gave a hypothesis. As someone who has pulled a fair amount of wire in conduit my recommendation is to go by the old rule of thumb and have no more than 360 degrees of bend in a run and be conservative in the number of wires you try to stuff through.

 

[ISX]

I realize the old rule of thumb which is what I normally go by, I just wondered if there was some technical proof showing which way would be easier. There are times when two 45's would be acceptable and even better looking, but you do a 90 instead just because of the old rule of thumb. I try to turn it into a fine art so getting away from old school is what I like to do, but usability is always top priority which is why I asked this. I didn't know there wasn't any way to prove which was easier other than just setting up the same conduits with the same wires trying the different bends. I just might have to try it someday and see.

 

[Averagesupernova]

I'm not sure you know what the 'rule of thumb' is. 2 45 degree bends on a run of conduit are the same thing as a 90 as far as the code is required.

 

[ISX]

Yes but rule of thumb also suggests you just do a 90 rather than 2 45's, 3 30's, 6 15's... I just wonder if there is anything wrong with the latter choice of bends. The wire bending multiple times theory is the only thing I have to go by right now other than going out and testing it.