Animal proof outdoor wiring?

[Mike1903]

Previous owner added some outlets by the front porch. They are fed by regular 12a NM cable that runs under the front deck and into the crawlspace ( though hole in the joist just above the foundation).
The underside of the deck is not accessible as it is built pretty close to the ground. Squirrels have chewed up the wire insulation, so, need to replace it.

is metal clad wiring approved for it or is PVC + individual strands the only option?
appreciate any other thoughts…thx

 

[mike93lx]

Conduit.

That nm shouldn't be there are all, regardless if the rodent damage. It isn't rated for outdoor use

 

[Terry D]

The NM-b is not allowed in a damp or wet location. Does the porch have a roof on it. If so, this might be a damp location. The NEC doesnt talk about MC in damp locations, just wet locations. It does say its allowed outdoors. I would say MC cable is allowed outdoors in a damp location as long as it has THWN conductors in it, but I would use the aluminum not the steel jacketed. But if you want to be on the safe side, they do make a PVC jacketed MC cable rated for wet locations. Sounds like a flexible cable might be your better choice for this installation. You would need a 14/2 or 12/2 depending on your circuit size.

But I guess something else to consider is that MC cable is not permitted when it is subject to physical damage. So is this location "subject to physical damage" with the squirrels. I cant see a squirrel chewing through it

https://nassaunationalcable.com/collections/armorlite-type-mc-copper-conductors/products/control-type-mc-600v?gclid=EAIaIQobChMI3JbzrODH9AIV1RvUAR1BTQGBEAMYAyAAEgKkqfD_BwE

 

[Mike1903]

The NM-b is not allowed in a damp or wet location. Does the porch have a roof on it. If so, this might be a damp location. The NEC doesnt talk about MC in damp locations, just wet locations. It does say its allowed outdoors. I would say MC cable is allowed outdoors in a damp location as long as it has THWN conductors in it, but I would use the aluminum not the steel jacketed. But if you want to be on the safe side, they do make a PVC jacketed MC cable rated for wet locations. Sounds like a flexible cable might be your better choice for this installation. You would need a 14/2 or 12/2 depending on your circuit size.

But I guess something else to consider is that MC cable is not permitted when it is subject to physical damage. So is this location "subject to physical damage" with the squirrels. I cant see a squirrel chewing through it

https://nassaunationalcable.com/collections/armorlite-type-mc-copper-conductors/products/control-type-mc-600v?gclid=EAIaIQobChMI3JbzrODH9AIV1RvUAR1BTQGBEAMYAyAAEgKkqfD_BwE

Thx, very helpful.
Yes, it does have root on it, so damp is more appropriate instead of wet. And, flex solution is preferred as the bottom of the deck is inaccessible. I will need to pry some flooring pieces but will look into flex MC before the conduit option.
I assume conduit + thwn instead of NM inside conduit?

 

[rlitman]

...I assume conduit + thwn instead of NM inside conduit?

Plain NM-b isn't allowed in damp locations, and conduit doesn't fix that. UF is allowed in damp locations, but has no metal to prevent chewing. The PVC covered MC mentioned above is often used outdoors for air conditioner hookups. LFMC (plastic coated greenfield) is another expensive flex conduit option that is chew proof.

 

[Terry D]

Thx, very helpful.
Yes, it does have root on it, so damp is more appropriate instead of wet. And, flex solution is preferred as the bottom of the deck is inaccessible. I will need to pry some flooring pieces but will look into flex MC before the conduit option.
I assume conduit + thwn instead of NM inside conduit?

Thats another tricky one. NM-b is not permitted it damp or wet locations, but 300.9 says when a raceway is installed in a wet location, the interior of the raceway is also considered a wet location. It says nothing about the interiors of raceways installed in damp locations. Would the interior of a raceway installed in a damp location be considered a damp or dry location. Is it even possible to have a dry location outside. Can that conduit sweat inside if one end is open to conditioned air from the house. The NEC defines a damp location as locations protected from weather and saturation of water, but subject to moderate degrees of moisture. One example of a damp location is a roofed open porch. I guess NM-b would be allowed in conduit in this location., But I personally would use THWN

 

[Mike1903]

Thats another tricky one. NM-b is not permitted it damp or wet locations, but 300.9 says when a raceway is installed in a wet location, the interior of the raceway is also considered a wet location. It says nothing about the interiors of raceways installed in damp locations The NEC defines a damp location as locations protected from weather and saturation of water, but subject to moderate degrees of moisture. One example of a damp location is a roofed open porch. I guess NM-b would be allowed in conduit in this location., But I personally would use THWN

thx.
I will see if I can source plastic clad MC cable locally; if not will go with THWN + conduit.
The wire is currently fed from the front door scone (idiotic move since a light switch controls the outlets). I will replace it and feed directly from the panel box so that it becomes a dedicated outdoor circuit.

 

[Norcal]

thx.
I will see if I can source plastic clad MC cable locally; if not will go with THWN + conduit.
The wire is currently fed from the front door scone (idiotic move since a light switch controls the outlets). I will replace it and feed directly from the panel box so that it becomes a dedicated outdoor circuit.

Give the vermin something to chew? The plastic is just more fodder, the only thing that is going to work is metallic conduits like rigid, or IMC.

 

[dcg9381]

Has anyone had rodent damage to PVC? I'm not against rigid or IMC - I just haven't used it... I've got PVC conduit all over the place (including places with rodents) and have never seen any indication of damage to anything.

 

[Innovate1]

I have had some rodent chewing on black poly pipe like used for sprinklers but haven't seen it on PVC. PVC is a lot harder so they may have tried and just not made much impression. It may not be completely rodent proof but pretty resistant. I would use PVC conduit for this. It doesn't rust and has reasonable resistance to vermin.

 

[Terry D]

If I had something under my porch gnawing through Pvc, I would be setting traps

 

[nadogail]

Rigid conduit is pretty tough to chew on, but installation is difficult.

 

[rburke65]

Conduit is the only way