I’ve got BX wiring in my barn and tool shed that looked really old when I moved in 25 years ago. Still functions fine, even the ancient electrical friction tape still works fine, provided I don’t move it. The only wire degradation is at the splice points. The copper wire will eventually start to corrode and discolor. Moisture, especially in wire nuts, will rot the wires off. If the box is not normally exposed to water just humidity the connections can be expected to last decades if not a few centuries. A moist damp basement can cause issues in tens of years. Splices that always get wet and not allowed to dry like car washes and saunas can rot in months. Sealed boxes help in those cases. There is a reason outdoor outlet boxes are sealed and have gaskets for the cover. Note, the degradation starts where the insulation is off the wire and seeps under the insulation. Modern wires are much better protected than the old paper and varnish insulated wires like I have.
I suggest you visit (search) Mike Holt for your electrical concerns. You will find much more authoritive references than here on SDMB.
I don’t know, that’s just info from the code. I’ve never actually seen either MC or AC wiring in as livestock barn – they mostly use UF now. Designed for underground feeder. it’s basically a sturdier, moisture resistant form of plastic coated NM (‘Romex’) cable. If it can stand actually being buried underground, the moisture & ammonia in a barn shouldn’t be that bad.
Interesting. I work as a manufacturer of MC, we only use aluminum armour at this particular plant. The inspector for UL is here often, and I’ve never seen a tag that said anything but MC
Do you work for Southwire by chance? All their MC is aluminum and they tag it MC.
I’ve been out of full time electrical for a little while now so maybe that trend has rolled over to others. Depending on what distributor I was dealing with if I just said ‘MC’ instead of ‘MC Lite’ I could end up with steel. It wasn’t a problem with the places that only carried aluminum.
NEC doesn’t make a distinction. Steel and Aluminum can be used interchangeable so it only matters to annoying engineers as far as I know. Other things they like to do is specify cast fittings…
I didn’t do any fire work but my understanding is MC for fire controls is only made in steel.
Not southwire, north of the border. I know we do some work with steel armour, but it’s on much larger gauges than you would wire a house with
Well as it turns out, i checked the wiring and it is in solid condition in the garage, apparently the house was rewired in 1989 and was very lightly used if that makes sense, so I’m going to leave it as is. connections are tight, clean, the insulation is a nice thick PVC or THHN type and covered in the steel armor. everything seems up well. Thanks for the information everybody! I still like knowing this stuff for future reference.
Off the tag in front of me
“ALSO CLASSIFIED THROUGH PENETRATION PRODUCTS FOR USE IN THROUGH PENETRATION FIRE STOP SYSTEM SEE UL FIRE RESISTANCE DIRECTORY”
I’m no electrician, I just make the stuff. Definitely aluminum though
I think that’s a distinction of pretty much all types of MC wire. That means you can run it through a fire block, caulked appropriately, without ruining the fire block. The cable wouldn’t transfer fire and air through the fire block more so than the fire block material.
Fire control wire is what you use to tie all the parts of a fire system together. In practice I think they just charge double to paint it red.
It looks like a few manufacturers do make an Aluminum fire control cable, so it’s not always steel. The steel ones advertise superior EMI protection over aluminum.
Ahh I see. Very interesting
My uncle built a livestock barn about 20 years ago. Wired it all with standard NM (“Romex”). He did an absolutely beautiful wiring job… there are no kinks or twists to be found.
He called his insurance company and told them he wanted the barn covered under his home-owner’s policy. When the inspector came out, he flunked him for not using UF. To this day the barn is still not insured.
As I mentioned previously, I wired my barn with MC Lite. It’s not a livestock barn, and it’s a dry environment, so I’ve always assumed it’s O.K.
I need clarification here. If by some miracle, a live and neutral crosses inside a MC cable (animal chewing, garage door crushing it), or a live touches the casing from the inside, would that trigger trigger a STANDARD, NON GFCI/ AFCI to trip? I keep reading up on all things electrical and there is never a straight answer, always ambiguous. A more direct “Yes, This is why?” or “No it might not, this is why” would be great. thanks!
AND NO! its not OCD related(boy do I regret ever admitting that before, afraid to post anything on here because i’ll hear about that).
A dead short will trip any breaker. But you really need to stop obsessing over an event that is as likely as a meteor falling on your house.
YES.
Much appreciated! Saves me a lot of time today not switching it out, I had my doubts putting in a GFCI/AFCI in the garage, if I use power tools in there or an air compressor, I don’t want any nuisance tripping. Seems like the standard ones won’t, so I don’t see any reason to change it out if it has that basic protection.
Thanks
A conventional circuit breaker (or fuse) deals with excess current. If the current is excessive versus the breaker’s rating it *will * (baring malfunction) trip. These things are *extremely *reliable.
It doesn’t matter if the current is diverted to ground via a ground wire, through a person or tree or plumbing, or there’s a short to neutral, or if the current is simply returning along the neutral exactly as designed but you’re trying to run too many appliances at once. Once too much current is detected it trips within a fraction of a second. As long as the current is less than the trip rating, it will let the current run forever.
These systems are designed to protect the building wiring from overheating from overload and thereby causing a fire. They do not protect the devices plugged in, nor do they protect people from stray voltages. At least not directly. Hence the later development of more advanced breakers.
GFCI breakers add an additional layer of protection to the above. In addition to all the above they do this: In a properly functioning circuit, all the power that goes out beyond the breaker on the hot side *should *be coming back in along the neutral side. If that’s not true, there must be a “leak” somewhere out on the load path where the electricity is going elsewhere; the breaker doesn’t know where it’s going, but it knows it shouldn’t be going there.
A GFCI detects that difference between the hot output and neutral return currents, worries that maybe the leakage is through a person, and immediately cuts the power. Even if the total current level is completely normal. That’s the good news.
The bad news is the threshold for detecting a leak is very, very small; a tiny, tiny fraction of a percent of the normal load. It needs to be that sensitive because an unlucky person can be killed by a very small current leak going through them for only a very short time.
A consequence of this exquisite sensitivity is that short term transient differences that aren’t really leakage can also trigger the breaker’s protection. These are the so called “nuisance trips”. Which, for technical reasons are especially likely if the load is a motor such as a garage door opener, an air conditioner or fan, a vacuum cleaner, or any power tool.
The upside is now this thing is directly protecting people, not just wiring. The downside is the occasional nuisance trip.
The next invention was the AFCI. It’s able to detect tiny transient faults where there’s either a loose connection, or an almost-break in a wire. These weaknesses still work fine most of the time, but they’re an exponentially deteriorating situation over time. And they’re a recipe for a fire once they thoroughly fail hours, weeks, or years after they begin.
The AFCI detects the characteristic signal of these proto-almost-failures. And trips in response. As with the GFCI, there are legitimate loads, again usually motors, that naturally crate signals that look similar to faults. So AFCIs are also prone to nuisance trips if applied to the “wrong” sorts of loads.
Hope this helps it all make more sense.
Hate to break it to you but if you can plug it in while standing on concrete it needs a GFCI. Garage, basement, exterior, kitchen counter, and bathroom outlets all get GFCI.
AFCI requirements still vary a bit depending on what code the local uses. In general it’s safe to assume any bedroom circuit will require an AFCI.
On a new construction house between GFCI and AFCI requirements you can hit $800 in just breakers. $5 dollar breakers were much nicer.
All I can say is, damn! Trying to save a little cash here. You’re right, new breakers are astronomically high. I have some good quality GFCI outlets lying around, i guess i’ll start with those first.
Thanks!