MC Cable support clarification

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69gp

Senior Member
Location
MA
Hi just looking for some clarification on supporting MC cable.

330.30 (A) says that MC can be supported by cable ties.

110.12 informational note makes reference to ANSI/NECA 1-2006.

ANSI/NECA 1-2006 Section 9 (Q) says that cable ties shall not be used to support conduit and cable.

I can see using cable ties to hold the cables in place but not to support the full weight of the cable. (the cables in the picture are a 4 conductor 250 MCM MC). I can see over time the cable tie cutting into the MC jacket and allowing moisture into the cable.


Which is the correct section to follow?.

Finally how is it determined that a cable is to be protected from physical damage. In the picture below the MC cables are run at a right angle to the racking and are 6 to 8" above the ground. I say that these are subject to physical damage by someone stepping on them or someone possibly hitting them with a weed trimmer when the grass is being managed. Granted the site is fenced in but these are not qualified personnel maintaing the grounds. My feeling would be to have EMT or Rigid conduit


IMG_20140726_175102626.jpg
 

iwire

Moderator
Staff member
Location
Massachusetts
Hi just looking for some clarification on supporting MC cable.

330.30 (A) says that MC can be supported by cable ties.

110.12 informational note makes reference to ANSI/NECA 1-2006.

ANSI/NECA 1-2006 Section 9 (Q) says that cable ties shall not be used to support conduit and cable.

I can see using cable ties to hold the cables in place but not to support the full weight of the cable. (the cables in the picture are a 4 conductor 250 MCM MC). I can see over time the cable tie cutting into the MC jacket and allowing moisture into the cable.

Which is the correct section to follow?.

Informational notes are not code, they are just suggestions. An AHJ enforcing the NEC cannot cite an informational note as a requirement.

We use cable ties to support cables every day, what you do will be based on the customer specifications and your desires.


Finally how is it determined that a cable is to be protected from physical damage.

That is entirely up to the judgment of the AHJ or the inspector.

In the picture below the MC cables are run at a right angle to the racking and are 6 to 8" above the ground. I say that these are subject to physical damage by someone stepping on them

Sure it could happen, but is it likely? Arnt't these located under PV panels?


or someone possibly hitting them with a weed trimmer when the grass is being managed.

I don't see a weed trimmer hurting those cables in the least. It is worth remembering these cables also have waterproof conductors inside them.

Granted the site is fenced in but these are not qualified personnel maintaining the grounds. My feeling would be to have EMT or Rigid conduit

If EMT was in that same location and was stepped on it would also be subject to damage. I think the likelihood of conduits being stepped on is much greater than for cables. People expect a metal pipe to support them, they don't expect a cable to support them.
 

69gp

Senior Member
Location
MA
the cables are exposed for about 30" between the rows so it could easily be stepped on.

Also the commercial weed trimmers used today have a steel wire wrapped with nylon. So it is a lot stronger than the ones that had just the nylon. I think it will do a lot more damage.
 

iwire

Moderator
Staff member
Location
Massachusetts
the cables are exposed for about 30" between the rows so it could easily be stepped on.

That sounds like a shortcut that will be used for walking. If it was me I might run short sections of J-line, strut or even short sections of pipe to tie wrap the cables to at these crossings.

I cant even guess what the inspector will expect or not.



Also the commercial weed trimmers used today have a steel wire wrapped with nylon. So it is a lot stronger than the ones that had just the nylon. I think it will do a lot more damage.

Could, might, maybe, if.

Not being a wise guy but that is what it always comes down to, it is an AHJ call as far as the subject to damage issue.


On the other hand the cable ties are directly allowed by code.
 

gadfly56

Senior Member
Location
New Jersey
Occupation
Professional Engineer, Fire & Life Safety
I'd be a little more concerned with the load those cables are placing on the cross strut. That's not Unistrut by any means and may not take that load over time.
 
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