1

Sometime ago I installed Siemens Load Center a 200 amps breaker panel along with upgrading of the meter socket, overhang + cable, and service entrance cable. The 200amps aluminum cable is very rigid and difficult to work with especially in very limited clearance: the cable enter the building through a wall right below the circuit breaker panel as depict in the pic below:

enter image description here [IMG]https://c1.staticflickr.com/1/463/32750491135_37daa6be3d_b.jpg[/IMG]

enter image description here [IMG]https://c1.staticflickr.com/1/429/32370165070_40ab0baa84_b.jpg[/IMG]

There is no clearance leeway and range to maneuver the cable in order to to get it properly clamped. However, this cable is extremely rigid and heavy duty and could not be disturbed or yanked in any way which would make the clamp irrelevant for most any practical purpose

Only by rerouting SE aluminum cable and drilling another lower hole in the exterior wall would allow another point of entrance with more clearance and thus allowing the reshape of the cable and having it properly clamped as far as appearance goes, but this would be too much work for no gain besides the avoidance of possible hindrances with the inspection. I was wondering whether the NEC would accommodate this type of situation.


I am considering redoing this segment (from bottom of meter box to breaker panel) of the SE cable and replacing it by copper and conduit instead of this type of aluminum SE cable. But I would imagine that this type of situation can crop up and that NEC should have some type of provision to deal with it. Besides the clamps server almost no function in this situation.

  • That bend looks a bit sharp to be code compliant. If your main breaker handle is below 6'7" move the panel up it looks like you have room to do this. I just realized your main is on the bottom the highest breaker at 6'7". I have seen panels installed upside down but not often. – Ed Beal Feb 8 '17 at 19:42
  • I can't tell is your main breaker side to side. Also make sure the instructions or box don't have the top listed. – Ed Beal Feb 8 '17 at 19:53
  • @EdBeal : It is less than 90 and it travel through the wall that consists of wood siding, rigid exterior insulation, plywood sheathing.. I guess the angle of curvature is rather sharp in relation to the how thick the SE cable is. Yep, the breaker panel is upside down. This is totally acceptable and makes the less thick wires running inside the panel. – tk3000 Feb 8 '17 at 23:40
  • 2
    The minimum bending radius for type SE cable is 5 times the diameter of the cable NEC 338.24. I am looking at the photo on my phone and it looks to be in violation to me. I could not see the direction of the main breaker if it is side to side and the panel doesn't have a "top" listed it would be legal but if the breaker is top to bottom the off position shall be in the down position NEC 240.81. In the county I live if the numbering on the dead face is upside down the panel is not installed correctly (some panels are made to flip the dead face). – Ed Beal Feb 9 '17 at 0:15
  • @tk3000 are you certain upside down I'd acceptable? Most places it won't be. Does the handle on the MN ain breaker move up and down? If so then the inspector should definitely have a problem with it. – Tyson Feb 9 '17 at 1:38
3

I would consider moving the panel down and bringing the cable in one of the knockouts on the back of the panel. That way the part of the cable inside sheath is a "straight shot", and need not be bent. Then you can remove the sheath and bend each of the individual conductors as needed.

  • Hard to tell on my phone but it looks like there is enough room to move it down.+ – Ed Beal Feb 8 '17 at 19:57
  • It would be problematic to move it down since there are other things in place (pvc elect box for the underground conductors coming from garage) and very little clearance. Besides, while it would hide the SE cable from view (once the panel cover is in place ) there still would be a need to bend the cable and thereby for a clamp, and a similar problem would emerge. I don't see how it could be a straight shot in this case. Also likely there would be a need to bore a large hole in the back of the panel for that option. – tk3000 Feb 8 '17 at 23:49
  • 3
    You wouldn't have to move it that far down. I see knockouts on the back wall of the panel (the vertical surface parallel to the lid which is not there) and that sort of connection is how it's commonly done. You could indeed go conduit from one of those KOs to the meter, and run individual strands of either Al or Cu. Nice thing about making the bend inside the box is you can strip the sheath back to 1/4" past the clamp, and bend the individual wires instead of trying to bend that ridiculously stiff sheathed cable. – Harper Feb 9 '17 at 1:07
  • 2
    @tk3000 - If you move the panel down the cable enters straight through the back. Clamping it should be relatively easy. You're right that it still has to bend, but now it's not the whole cable bending, but each conductor individually. That's considerably easier. – Mark Feb 9 '17 at 2:42
  • @Mark - that would make the panel considered lower which is ok, but the knockout are not lined up with the hole in the wall, besides I can not move the panel left or right since some conduit (transfer switch on the exterior side of the wall) enter the panel from its left side. By doing that I would need to remove the panel, bore a large hole that would line up with the hole in the wall, install the clamp in advance, and then reinstall the panel. I see your point that it would be easier to bend the individual conductors. Yeah, that is an option I am considering. – tk3000 Feb 11 '17 at 2:57
1

This is not necessary a response or a solution, but a rather late coming follow up.

The breaker panel was lowered few inches, and from outside I used an elongated drill bit in order to drill a pilot hole through-through and in the panel. This pilot hole was then used as a reference to drill a 3" hole from inside with a bi-metal hole saw, and the end result was a hole in the panel that coincides with the hole in the wall -- actually the hole is slightly larger in order to accommodate the clamp for the service entrance cable that must be fitted in the breaker panel hole.

enter image description here

After lots of elbow grease, I was able to pull out this aluminum serv entrance cable from outside and reinsert it with the new configuration and orientation. The sheathing of the serv entrance cable got jammed in the hole during the pull operation and did not pass through.

enter image description here

In this situation I believe that the whole cable is not bent under the panel as it enters the building, but instead its individual conductors enter the building and then each conductor is bent 90d as it enters. Any insights and input would be appreciated.

https://c1.staticflickr.com/3/2875/34015964855_5be43dca13_h.jpg

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.