[Habeed]

Ok, I've got a reel of MC cable. I've got a square D QO panel, where all the wires have apparently been stuffed into the panel through a short PVC pipe that goes from the panel into the inside of a wall, and then on to their destination. So I cannot use a knockout.

I can strap down the MC cable to a nearby stud, but how do I bond the metal outer sheath to the metal of the outdoor main electrical panel? The internal cable ground is insulated and not connected to the outer sheath. I could return the cable and buy the type that has a ground wire bonded to the armor itself, but there must be some legitimate solution to this problem.

 

[Barjack]

MC cable needs to be connected to a box, panel, equipment, etc using the proper fitting. That's how it makes the bond for the outer jacket.

If I'm reading correctly, you have free conductors (not cable assemblies like romex or MC) in conduit, and you want to pull the MC through that into the panel? That's a no go legally.

You should bring the MC into the back of a metal outdoor box somewhere close to the panel, like a bell box, then run conduit to the panel, installing the necessary conductors including an equipment ground.

 

[Habeed]

MC cable needs to be connected to a box, panel, equipment, etc using the proper fitting. That's how it makes the bond for the outer jacket.

If I'm reading correctly, you have free conductors (not cable assemblies like romex or MC) in conduit, and you want to pull the MC through that into the panel? That's a no go legally.

You should bring the MC into the back of a metal outdoor box somewhere close to the panel, like a bell box, then run conduit to the panel, installing the necessary conductors including an equipment ground.

So this requirement is specific to using MC. If I use Romex instead, the Romex can just stop at a strap or securing point within 12 inches of the box, then enter the plastic conduit as free conductors from inside the wall, right?

That's how it is currently wired, by whoever worked on this place last...

 

[rjniles]

Terminate the MC in a metal box above the panel and run NM into the panel.

 

[Habeed]

Terminate the MC in a metal box above the panel and run NM into the panel.

Not an option. Apparently, whoever did the work on my house decided to simply secure (usually...) the romex to the inside of the exterior wall behind the exterior electrical panel. They then just shoved the Romex into a 2" PVC coupling going into the box. They then stripped the romex back and got to wiring. It looks like an amateur mess to be honest, but I don't see anything unsafe. I won't be able to use MC cable it appears, however.

 

[J. V.]

Open the panel cover. Find unused KO. Pop it out. Attach MC connector to MC cable. Then drop or fish the MC connector through the open KO and install a lock nut or other fitting required for MC.

 

[Habeed]

Open the panel cover. Find unused KO. Pop it out. Attach MC connector to MC cable. Then drop or fish the MC connector through the open KO and install a lock nut or other fitting required for MC.

Can't. All those knockouts are exposed to outside.

 

[Barjack]

Is the cable going to be exposed or something? I'm wondering why you wouldn't just use romex?


Sent from my iPhone using Tapatalk

 

[Jim Port]

I get the impression that the panel is surface mounted outside. I don't see how the install ever passed inspection.

 

[Barjack]

I get the impression that the panel is surface mounted outside. I don't see how the install ever passed inspection.

If the NM cables are coming down the inside of the exterior wall, aren't exposed to damage, then nipple into the back of the panel, I don't see a problem with it. In fact, I've done many panel installations just like that, and passed inspection.

I do wonder if the cables pass through an MA, or a coupling with a box adapter?

 

[Habeed]

If the NM cables are coming down the inside of the exterior wall, aren't exposed to damage, then nipple into the back of the panel, I don't see a problem with it. In fact, I've done many panel installations just like that, and passed inspection.

I do wonder if the cables pass through an MA, or a coupling with a box adapter?

It seems to be just an open piece of PVC embedded into the wall. Basically like this. Image is in bottom third of the page. Makes me feel better about doing DIY work on this place - to be quite frank, I can't do worse than the last guys.

All those neat professional installs where the wires are neatly separated by type into perfectly straight bundles? Haha nope, in my box they are just kind of an unruly mess. Nothing's overloaded and everything goes to a single breaker, so I guess it's legit, but it won't be very hard for me to do work of this caliber even as a complete amateur...

 

[Jim Port]

Are you talking about post #18 in that link?

 

[Habeed]

Are you talking about post #18 in that link?

Yes. But not as neatly done as that. House only has 150 amp service, so if you think about it that way, that tight NM bundle can only get so hot.

I think I read somewhere that for bundles you're supposed to use the 60 C numbers. Well, the ones here are exactly the same ampacity regardless of temperature - I guess this table is being conservative - and as you can see, 14 gauge is good for 15 amps, 12 gauge for 20 as usual.