UF (underground feeder cable) 12/4 ?

[brother]

Its been hard to find UF cable 12/4 , basically 2 hots 2 neutrals with ground. Was having a discussion with another guy that was installing his disconnect with receptacle for the hvac unit at a dwelling. He thought he could use regular romex 12/3.. Its a technicality but romex is not rated for outside as his disco will be outside even though the feed is coming from underneath (crawl space) from the house and feeding the back of the disco.

Also the hvac condenser and receptacle shouldn't be sharing neutrals, even from a 'feeder' (NEC definition vs branch circuit) as this would defeat the purpose of of the receptacle if they needed to shut off the breaker for the diso, (shared neutrals must have common disconnect). Is there a code against this on feeder side?

Cant seem to find 12/4 uf as readily and cheap at the big box stores, do they make it often? What do you think of him wanting to share the neutrals on the 'feeder' side? I couldnt find a NEC code that forbade it, just that its not good practice.

 

[infinity]

He thought he could use regular romex 12/3.. Its a technicality but romex is not rated for outside as his disco will be outside even though the feed is coming from underneath (crawl space) from the house and feeding the back of the disco.

You can enter an exterior disconnect with NM cable that is run in a dry location. Is the crawl space in this installation not a dry location?

 

[brother]

You can enter an exterior disconnect with NM cable that is run in a dry location. Is the crawl space in this installation not a dry location?

yes the crawl space (under house) is a dry location. I always understood it as a 'technicality' , and I believe inspectors here are enforcing it that way as well. The wire connection from the romex is connecting in a wet location (outside in disconnect box) so the romex cannot do that. Is this enforced differently in your area?

 

[wwhitney]

If the cable goes from the crawl space (dry location) through a wall (dry location) into the interior of the enclosure (dry location), where is it ever in a wet location?

Cheers, Wayne

 

[infinity]

I believe inspectors here are enforcing it that way as well. The wire connection from the romex is connecting in a wet location (outside in disconnect box) so the romex cannot do that.

The inside of the disconnect is a dry location. Running the cable in a dry location to the dry location inside of the disconnect is permitted. Otherwise every outdoor receptacle or light fixture run with NM cable to an FS box would be a violation.

 

[LarryFine]

Its a technicality but romex is not rated for outside as his disco will be outside even though the feed is coming from underneath (crawl space) from the house and feeding the back of the disco.

This is considered to be compliant.

Also the hvac condenser and receptacle shouldn't be sharing neutrals, even from a 'feeder' (NEC definition vs branch circuit) as this would defeat the purpose of of the receptacle if they needed to shut off the breaker for the diso, (shared neutrals must have common disconnect).

The condenser wouldn't have a neutral connection.

 

[infinity]

The condenser wouldn't have a neutral connection.

Yes so a single 12/4 NM cable would be fine. You wouldn't even need to re-identify a conductor.

 

[brother]

This is considered to be compliant.


The condenser wouldn't have a neutral connection.

Its 120v unit. Its for a mini split. so it has a neutral.

 

[infinity]

Its 120v unit. Its for a mini split. so it has a neutral.

Okay then 12/2/2 would work.

 

[Master Nater]

Its 120v unit. Its for a mini split. so it has a neutral.

so share the neutral and put it on a 2-pole breaker. you have to put a disconnect outside at the mini-split condenser anyhow. have that maintenance disconnect only disconnect the condenser 120v lead. the receptacle stays on.

 

[LarryFine]

Its 120v unit. Its for a mini split. so it has a neutral.

Now you tell us. I'd opt for an MWBC, and an SP switch disco.

 

[readydave8]

as this would defeat the purpose of of the receptacle if they needed to shut off the breaker for the diso

I think the receptacle just needs to stay hot if disconnect is shut off, not breaker?

 

[pipe_bender]

Is the crawl space in this installation not a dry location?

Inspectors classify based on the vapor barrier, some crawlspaces and unfinished basements are damp locations and the vapor barrier is plastic stapled under the floor joists. I would need more info to be sure the crawlspace is a dry location.

 

[brother]

Okay then 12/2/2 would work.

Thanks for feedback. looks like the big box stores done have 12/2/2 in 50ft rolls in stock here. They claim they dont sell much of it. with your feed back and sharing a neutral on the feeder, he can use the 12/3. to the disco, if he wanted to, its just not optimal.

 

[infinity]

Inspectors classify based on the vapor barrier, some crawlspaces and unfinished basements are damp locations and the vapor barrier is plastic stapled under the floor joists. I would need more info to be sure the crawlspace is a dry location.

He said that in this case it is a dry location so NM is permitted and UF would not be required.

 

[brother]

Inspectors classify based on the vapor barrier, some crawlspaces and unfinished basements are damp locations and the vapor barrier is plastic stapled under the floor joists. I would need more info to be sure the crawlspace is a dry location.

they had a vapor barrier put in some years ago when they put in more insulation, didnt look to great of a job they did with the vapor barrier. some of it moved not 'taped' togheter on the dirt ground. But I guess it still keeping most of the moisture out. Some said they only seen very little.

Interesting some inspectors use the vapor barrier to classify a damp location. What about the existing romex stapled to the studs and no vapor barrier in those places.;-)