Type MC cable

[mbrooke]

Why doesn't type MC cable have a bonding strip? What if the middle of the run was damaged or drilled into?

 

[infinity]

Because it has an insulated green conductor as the EGC. The jacket is still bonded by the connector at each end and not designed to carry the circuit fault current but I see your point if the jacket itself was faulted by a screw or something.

 

[mbrooke]

Because it has an insulated green conductor as the EGC. The jacket is still bonded by the connector at each end and not designed to carry the circuit fault current but I see your point if the jacket itself was faulted by a screw or something.

Without the bond strip the jacket would present a high impedance path during a fault internal to the cable itself.

 

[infinity]

Without the bond strip the jacket would present a high impedance path during a fault internal to the cable itself.

My guess is that the odds of it being a problem are very slim so it's not a concern.

 

[tkb]

It should be bonded on both ends if properly terminated.
So if damaged in the middle, it would have a fault part either way.

 

[gadfly56]

Why doesn't type MC cable have a bonding strip? What if the middle of the run was damaged or drilled into?

'Cause then it would be AC, but with a ground wire.

 

[tom baker]

Smart MC cable has a bond strip if that is a concern, then switch to it. It saves 30% time on installations.

 

[mbrooke]

My guess is that the odds of it being a problem are very slim so it's not a concern.

Until it happens... there was a PDF of a burned up MC cable in a butcher shop.

 

[mbrooke]

It should be bonded on both ends if properly terminated.
So if damaged in the middle, it would have a fault part either way.

But no bonding strip to lower the Z.

 

[gadfly56]

But no bonding strip to lower the Z.

So, basically are you saying they should ban MC? Or require the strip and have only a hybrid product?

 

[infinity]

Write a proposal for a ban due to the infinitesimal possibility that something bad can happen. Infinitesimal with no substantiation seems to dictate what they'll approve.

 

[tom baker]

Write a proposal for a ban due to the infinitesimal possibility that something bad can happen. Infinitesimal with no substantiation seems to dictate what they'll approve.

Unless its for a GFCI requirement, like a drinking fountain.

 

[electrofelon]

I agree with mbrooke that logically, it is kinda odd. Generally something needs to be an approved egc per 259.118, but not for itself ?

 

[mbrooke]

So, basically are you saying they should ban MC? Or require the strip and have only a hybrid product?

Require the strip... although the CMP has other ideas

 

[romex jockey]

Without the bond strip the jacket would present a high impedance path during a fault internal to the cable itself.

exactly what BX is famous for

~RJ~

 

[LarryFine]

exactly what BX is famous for

and infamous.

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[tkb]

I will bet if the MC cable is so damaged the the EGC is severed, a bonding strip will not be much better.

 

[hbiss]

I will bet if the MC cable is so damaged the the EGC is severed, a bonding strip will not be much better.

Exactly!

-Hal

 

[hbiss]

Until it happens... there was a PDF of a burned up MC cable in a butcher shop.

Wanna see that. Betcha it had nothing to do with the lack of a bonding strip.

-Hal

 

[romex jockey]

The outer shell of armored cable is 5-6X's the conductors inside, thus significant Z dif. In older homes typical with horsehair plaster ,it was not uncommon to find a line of dots , not necessarily rust , from it ~RJ~