Is it code to use armored cable in a barn, and use plastic junction boxes? Its all open wall and ceiling,I was going to use the 12-3 armored for all the runs split the 12-3 for the lights and outlets then use two breakers for that whole run.

As you said barn it may well be an agricultural building per 547.1(A) and (B).

If it is an agricultural building steel jacketed AC cable is out of the question.

Also and more importantly, plastic boxes with steel cables and raceways are a very bad idea.

At the least you should read Article 547.

Where I am at (Ontario Canada), standard practice in older wooden/open frame agricultrural buildings is NMW-10 cable (AKA UF-B), and surface mount bakelite fittings. New er "closed frame" barns will have PVC conduit and fittings. The service panel is either in a "doghouse" on the outside of the barn, or in an anteroom or mechancial room sealed from where the livestock is kept.

If this is an agricultural building as described in 547.1(A) or (B), MC cable would be allowable but definitely not AC. And if MC cable were used, plastic boxes would have to meet the exceptions to 314.3, otherwise they are not permitted with metal raceways or metal-armored cables.

That MC would have to have a plastic jacket as well.

This barn is all wood has two horses in there own stalls, used for horses only big sliding doors, armored cable is my first choice. I dont want any rats chewing wire, is this ok? I will be in Riverside county, Ca for this job. This is the best forum for questions and answers, something you can't get at Barns and Noble book store.

No typical armored cable is not OK.

The only armored cable allowed would be jacketed MC cable which looks like prewired liguidtight. It is not cheap.

UF cable (looks like NM) is OK but I would go with PVC conduit with PVC boxes.

Ok, looks like pvc with plastic boxes will do, the concern was stories I read about barn fires caused from metal boxes rusted from moisture with changing temperture's and animal waste the acid's speeding up the decay on metals, That would be great if there was a spray coating that could protect the armored cable like a rust proof application.
Now one point I wanted to make was the armored cable if out of reach like the ceiling runs, would that exception be possible? Ok Ok OK the secrect is out. I love armored cable, but I love horses also I want to be the safest first!

Whats wrong with regular aluminum MC? It is wet location listed according to the box. I can see a grounding issue with plastic boxes if the connector doesn't have a bonding lug.

Nothing, except it is not allowed by 547.5(A)



I believe corrosion is the issue, notice only copper SE cable is allowed.

Notice the absence of RMC and FMC from the list.

Schedule 40 and 80 PVC would be IMO, the way to go in a horse barn. (80 where exposed).
You want to keep the wiring as up high and protected as possible. Also you might consider putting a switch in a remote location to turn the barn lights on. Also use lighting that will come on instantly without a warm up period.
Horses can get into lots of trouble, and it's no fun trying to go into a dark barn to try to save them.
If the lighting is suspended from ie: chain, and connected with a short section of LTNMFC, vibration and shock won't be transmitted to the lamps, and they will last longer.
I used to care for 100-200 horses (in Riverside County, CA ) My boots would usually last < 3 months, even with constant care. Now I get a year or so out of them.
Armored Cable without a jacket, like iwire says, would not last much longer than my old boots. It's really that corrosive of an environment.

Nice shot Bob!

I guess I have to learn a little more about barns.

I'm surprised the AFC guy didn't pitch that when they were selling us on how great MC was last month at the IEAI meeting.
He did have some jacketed he was passing around.

Thanks alot Everybody for your valued info, looks like plastic to me its going to be.

Amazing....we have an application where you can use romex- but not rigid, IMC, or EMT!

Electure, have you ever seen rodent damage on romex or exposed wirning in the barns you were working with. Thats a concern here with the mice and rats.

I never had a problem with rodents chewing the wiring. They seemed to prefer chewing on the wood.

The rats I had problems with were more of the 2 legged variety.

i mean just to understand this topic
the preferred wiring method in a barn is pvc
conduit?So the whole thing has to be in pvc?
And what was it about the uf?
i know,i am slow

I,ve wired a bunch of horse barns, and plastic boxes will not hold up it's also a good ideal to keep every box and conduit out of reach from the horses