I know the NEC has no definition on what constitutes a large or long radius elbow/sweep, but every manufacturer seems to start at a 12" Radius. They all reference UL 6. I do not have access to UL 6 and I'm curious if anyone here has read it and does it define the requirements of a large/long radius sweep?
Long/Large Radius Sweep
- Thread starter quantum
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- New Jersey
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- Journeyman Electrician
What do you mean by they start with 12"? There is a radius table, Table 2 in Chapter 9 of the NEC.
That would be the minimum bend radius. What I mean is, if you look at the product sheets for a lot of major manufacturers, you can buy "Standard Radius Factory Elbows" or you can buy "Large Radius Factory Elbows" and they always start at 12" Radius on the "Large Radius Elbows" no matter the manufacturer. They usually reference UL 6. I'm curious if these manufacturers are simply choosing logical sizes 12", 24", 36" Radius or if there is something in UL 6 that defines the minimum bend radius to be considered Large/Long radius.
Here is an example:
http://www.alliedeg.us/galvanized-rigid-steel-conduit/grc-elbows/
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- New Jersey
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- Journeyman Electrician
The 12" radius is only for 1" and 1.25"-90° long sweep elbows in the tables you provided. Anything beyond the minimum standard radii listed in the first table (that mimics table 2 in the NEC) would be a design choice.
That's what I'm getting at. I believe it is a design choice, but I have a customer that insists on me providing "large radius elbows" but he can not give me a definition. The only bit of research I have not done is read UL6 to see if they have any kind of definition on what constitutes a "large radius sweep". I'm hoping someone here has maybe read or has access to UL-6.
jumper
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I understand your question.
Could be a UL thing or just a consensual standard among manufacturers. I have no clue.
For myself, I see the question as:
What is the minimum radius needed to be considered a large radius elbow, and who and why was that dimension adopted/accepted?
Could be a UL thing or just a consensual standard among manufacturers. I have no clue.
For myself, I see the question as:
What is the minimum radius needed to be considered a large radius elbow, and who and why was that dimension adopted/accepted?
- Location
- New Jersey
- Occupation
- Journeyman Electrician
Usually when a larger than normal sweep is specified the person making the specification provides you with the minimum radius that they will accept. If they don't know then I would ask if you could just use larger sweep elbows that are commercially available. As you can see from your table of different radii the term is very generic.
That is an excellent way to put it!
I have several customers that specify that they want 5X or 10X the conduit diameter, but this particular customer does not. I'm doing all my research prior to making my argument that there is no set value, but the final stone I have not turned over is UL 6.
- Location
- New Jersey
- Occupation
- Journeyman Electrician
UL6 is the standard used for the manufacturing of RMC I'm not sure that it will provide any of the information that you're seeking.
I believe you are taking the correct approach trying to get your info up front. Since there appears to be no clear answer why not SUBMIT to them the radius of each size of RMC and make them approve it. If you are wanting to buy factory sweeps instead of bending them then make sure the submitted radius is what you can buy.
I'm not sure either, but you never know if it doesn't provide a minimum radius for "long sweeps." Hopefully someone here has read or has access to UL 6 to confirm.
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