SE Bending

[fussyinspector]

Today I ran across a panel with 360 degree bend in SE Cable. Just wondering if anyone comes across this a lot. Contractor of course said he had never heard of the code. had to send him to 338.24 nec[:-monkeyd

[Les]

Why 360? How did that work?

[fussyinspector]

it was a loop in the panel instead of cutting to fit... some contractors try to give a little extra for mistakes.

[hausdok]

Why would a 360 degree loop be an issue if the bend radius is not less than 5 times the diameter of the SEC?

ONE TEAM - ONE FIGHT!!!

Mike

[fussyinspector]

It was less than 5 times the d. tight fit in the box. it would have been just as easy to go straight to main.

[Greg Booth]

..........one good reason for the added length is for frost heave. In my area, the AHJ's are always looking for slip-joint expansion couplings in the riser conduit on meter peds. What good is it to have the ability for the conduit to extend with frost heave, yet the cable contained/constrained within to be fixed in length? Those 360 dergee loops work very well..........Greg

[Jim Port]

A loop in the panel would have been in a conductor, not the cable that 338.24 applies to.

[Mike Lamb]

Pictures?

[Douglas Hansen]

If you are talking about a bend in the individual conductors inside the panel, with no sheathing on them, that is how I would wire it. I prefer making that loop so there is something there in case the connections at the terminals ever need to be redone. 338.24 only applies to the cable with the sheathing in place.

If what you are talking about still had the sheathing on it inside the panel, I would agree the electrician was a bit loopy.

[hausdok]

I've seen them bring those into panels many times, make a 360 degree turn on either side of the breaker banks and then connect them to the main lugs. I'd measure them and ensure the radius was not less than 5 times the diameter of the conductor and if it wasn't I wouldn' give it another thought unless there was limited space or the connections weren't made neatly, etc..

I think if there's room there to do it that it's making a mountain out of a mole hill. Then again, what do I know. I used to think that bonding a panel was paying a guy to get it out of jail.

ONE TEAM - ONE FIGHT!!!

Mike

[Douglas Hansen]

There is no minimum bending radius for individual conductors, only for cable assemblies. There is a rule for the amount of space needed between the panel wall and the terminals. If the conductors exit the wall opposite the terminals, it is based on table 312.6(B) and assumes two bends will be needed in that space. If you look at the numbers in the table, it will work out to somewhere between 5 and 7 times the diameter of the cable most likely to be used in the lugs.

You often see very sharp factory-made bends on service equipment. It isn't a problem. At low (<600) voltages, it isn't going to affect conductivity, strands of conductors aren't going to be stretched or damaged, and insulation will remain intact. Medium voltage cables with layers of dielectric insulation do have a minimum bending radius. House wiring doesn't. What matters is that the conductors lay into the lugs without adding stress to the connection. That is much easier to do if you make a loop rather than trying to run them the shortest distance.

A proposal was made to add a minimum bending radius in the runup to the 1978 code. It received no support.

[Richard Moore]

...

I used to think that bonding a panel was paying a guy to get it out of jail.

Hang on to that day job, Mike!

[hausdok]

Richard,

When the hell did Dudley start moving? That just freaked me the hell out.

ONE TEAM - ONE FIGHT!!!

Mike

[Richard Moore]

He's been doing that for maybe 3 or 4 months now. Clever doggie!

[Les]

Richard,

Mike O is a tad envious because that thing in his avatar has't moved in months!!!

[Richard Moore]

Now THAT is funny! Thanks for the morning chuckle, Les.

[hausdok]

Richard,

Mike O is a tad envious because that thing in his avatar has't moved in months!!!

Actually it has. The "thing" is the engine in my P.H. It's now five miles from there on an engine stand and the chassis is in a kajillion pieces a few feet away getting sand blasted and rebuilt.

ONE TEAM - ONE FIGHT!!!

Mike