Calculating the distance needed between a bend in conduit and conduit threads

[krus]

I am designing a project with a good amount of conduit. I will need a couple 2" conduit runs coming out of my panel. I would like to be able to come out of the bottom of the panel into an LB then bend the 2" to 90degrees and run up the backside of the panel. My main concern with this is that the bend would have to be fairly close to the threads needed for the LB. I have no problem keeping the minimum bend radius found in the NEC (about 9.5") but is there a standard or a general industry rule of thumb for how far away from the bend I should keep my threads or am I just limited by my bending and threading equipment? I would like to be able to have a standard for all sizes of conduits for any future design work I do.

 

[infinity]

So you're looking to come out of the LB with a 90° elbow? What kind of raceway? The shortest elbow would probably be a factory bend. For RMC a field bent elbow will be longer even if you bent it right at the thread.

Welcome to the Forum.

 

[krus]

So you're looking to come out of the LB with a 90° elbow? What kind of raceway? The shortest elbow would probably be a factory bend. For RMC a field bent elbow will be longer even if you bent it right at the thread.

Welcome to the Forum.

Ideally I was hoping for an end bend of the conduit but I might have to consider a factory 90 degree elbow like you said. The electrician told me he needed 9" off the bend to make this work and I was just trying to get an idea if this was realistic. I will look at what minimum distance I can maintain with a factory elbow. Thanks for the suggestion

 

[LarryFine]

I'm trying to picture it.

Can you run the conduit, put on the 90, then the LB, then mount the panel?

You must leave the panel at the bottom, meaning can't use the top or back?

Do you have access to the back, perhaps two LBs with a nipple forming a U?

 

[infinity]

Ideally I was hoping for an end bend of the conduit but I might have to consider a factory 90 degree elbow like you said. The electrician told me he needed 9" off the bend to make this work and I was just trying to get an idea if this was realistic. I will look at what minimum distance I can maintain with a factory elbow. Thanks for the suggestion

I'm not sure what the length of a 2" RMC elbows is but a factory elbow will be the shortest you can get. As Larry suggested you may be able to use use two conduit bodies and an LB facing forward and either a LR or LL facing the side.

Whenever you're using conduit bodies you need to check the maximum conductor size permitted within the conduit body.

 

[LarryFine]

How many conduits? If you can roll them to either side, you can decrease the needed depth.

If you have room to either or both sides, you can come out at 90 degrees, needing no depth.

For that matter, maybe you can use the side KOs of the enclosures instead of the bottoms.

 

[NoahsArc]

Keep in mind that when you bend conduit there is a segment past the nominal end of the bend where the pipe is still deformed in cross section and as such is difficult/impossible to connect to a fitting.
Offhand, it's usually 1-2x the diameter of the pipe for EMT, roughly. So on a 2" conduit I wouldn't try to slap on a fitting unless the top of the fitting was going to rest at least 2-3" below the end of the bent portion, or you want to spend a lot of time with large channellocks trying to squeeze the eccentricity out of the pipe.

For IMC/RMC and threading, this might not be as big an issue, I haven't run those enough in recent memory to recall.

The electrician told me he needed 9" off the bend

That's the minimum bend radius I think. See above.

 

[NoahsArc]

I also want to say I remember my very first conduit body I installed. It was in April 2016, two sticks of half inch EMT and an outside corner on an exposed hallway. It was an overcast day, and the CMUs in the hall had been painted medium gray. It's vivid in my mind, because it's special, because that was the first and last time I touched a conduit body. I've probably installed at least 30,000 feet of conduit since then.

So I'm a little suspect that a conduit body is needed here.

 

[infinity]

Keep in mind that when you bend conduit there is a segment past the nominal end of the bend where the pipe is still deformed in cross section and as such is difficult/impossible to connect to a fitting.
Offhand, it's usually 1-2x the diameter of the pipe for EMT, roughly. So on a 2" conduit I wouldn't try to slap on a fitting unless the top of the fitting was going to rest at least 2-3" below the end of the bent portion, or you want to spend a lot of time with large channellocks trying to squeeze the eccentricity out of the pipe.

Yes for EMT it's typically the trade size of the conduit from the end for mechanical benders. If you put the fitting or conduit body on before making the bend you can place the front of the bender right against the fitting or conduit body which will give you the shortest field bend possible without cutting the raceway. This is 4" EMT:

 

[NoahsArc]

Now that's a nifty trick.

 

[JoeStillman]

I would make the u-turn in a 12 x 12 wireway instead.

 

[Strathead]

I am designing a project with a good amount of conduit. I will need a couple 2" conduit runs coming out of my panel. I would like to be able to come out of the bottom of the panel into an LB then bend the 2" to 90degrees and run up the backside of the panel. My main concern with this is that the bend would have to be fairly close to the threads needed for the LB. I have no problem keeping the minimum bend radius found in the NEC (about 9.5") but is there a standard or a general industry rule of thumb for how far away from the bend I should keep my threads or am I just limited by my bending and threading equipment? I would like to be able to have a standard for all sizes of conduits for any future design work I do.

The best answer to your exact question is... You need to download the manual for the bender that will be used to bend the conduit You will find charts that provide you with the stub up length required. It is marginally different from bender to bender.