I have some 14 gauge "BX" or Armoured cable that I want to use in my Garage for some more outlets etc. but I am not sure if it is OK to use. Why I am not sure is that there is no ground wire in it. There is only a black, and a white wire in it with the paper wrap, then the armoured sheathing. I believe that the jacket is used as the ground, but I am not sure if that is legal, or safe. I live in Ontario Canada if that matters. Thanks for any help I may get.
Duane
you should have a ground wire in it.
If I had it, I would use it -- with a GFCI upstream. Use the armor for a ground, and the GFCI will trip if there's a fault.
I don't know for sure if that would be legal, but it is safe and it should be legal. Without the GFCI there would be a fire risk if there were a short from hot to ground if it didn't quickly draw enough current to trip the breaker.
Best regards, Bob
wait till you have to pull out a receptacle to change it or check it and the steel jacket which you attached (with great difficulty) to the ground screw breaks off. and ends up too short to use so you have to pig-tail it. you'' soon figure out that saving 10 bucks wasn't worth it. ...thehick
I have no idea about Canadian laws, but in some (very few) parts of the US, it is used and Romex type wire is illegal. It's safer too because if somebody drills or hammers through it, they will hit the shield first.
You need to know how to use it, though. It should be used with metal junction boxes exclusively. No plastic. It should be cut with a BX cutter, or a hacksaw (you have to know how, but you cut just one small piece and the whole thing untwists. It's hard to describe but easy to show.) You also need to put a plastic bushing at each end.
It's harder to knock the cable out of the connector than it is to knock a wire off a ground screw, so safety is not the issue if you do it properly. Incidentally, where I grew up, it was required inside walls, unless you wanted to use solid conduit. It was not allowed on exposed walls or ceilings.
I'm assuming that the wire you would normally use is cheap enough that it should not be a major issue though, unless Canadian wire is vastly different from what most of the US uses.
The steel jacket gets clamped to the metal box; the receptacle gets grounded to the metal box. I don't see a problem (as long as he protects the circuit with a GFCI, which I said in my previous message and you trimmed it off.)
Bob
And what do you attach to the GREEN screw on the receptacle? Nothing connected? It's not safe. PERIOD. You can't depend on the dogears of the receptacle grounding to the box.
A pigtail to a grounding screw on the box. Or use a self-grounding receptacle. Really, it's not that hard...
Bob
first off, i agree, this isnt the place to save 10 bucks and it would probably be better/easier to use more 'proper' wire. not for safety issues so much as its going to be a pain in the butt.
however... you simply attach a wire from the green screw on the receptacle to a green(ground) screw on the metal box.
randy
It depends on what receptacle he uses. If it is "self grounding" you don't need to connect anything to the green screw.
uhhh, they have continuity with the ground pin, they are attached permanently, they are held in connection to the box via screws.
In other words: Yes you *CAN*, you nitpicking idiot.
If this is so, why won't it pass electrical inspection (at least here in Calgary)?
...and I agree, a wire between the box and green screw is fine if the box is grounded. Not sure if I'd be happy using the sheathing but it would work.
You can't depend on metal sheathing to have continuity. The most kosher way, and would probably meet most codes, would be to run a green wire (THN, whatever) alongside the bx. The ends of this wire would be connected just like the bare wire in 12-2WG. Unless it's a fairly long run, I don't know that it would be worth the trouble, though. Bill
Outlets in the garage should probably be GFCI protected anyway. The armour will protect the wires, and it should provide a good enough ground to trip the GFCI in case of a fault.
Bob
If you garage isn't a place of assembly or capable of being so(that would be a good size garage), the US's NEC allows you to use it. But..... You need to check with local codes, and figure out if the cable can be exposed to physical damage.
It being a garage he needs to use gfci's in the US.
Good ground would quickly trip the breaker, but being that he's asking about the cable, he's probly already in violation of the NEC. Only qualified people to work with electricity. :-P
later,
tom @
First if you have nothing to goto the ground screw on the recept you attach nothing. In this case, he has a few options.
If the box is properly grouned, run a bare copper conductor(solid) between the ground on the box and recept.
Another option is to removed those little cardboard pieces, and if the box is metalic and grounded, the yoke 'auto-grounds' to the box, I don't remember where this is 'allowed' if anyone can refresh my memory please do.
Now here is where you run into problems, if the recept's manufacture states a ground must be installed, then you only have one option, or you violate US NEC. Labels and listing.
Remember only qualified personnel should work on electrical systems.
later,
tom @
Underwriters Laboratory of Canada has researched this topic and found that connections to ground of ordinary receptacles using only the mounting screws are unreliable. That is why they apply an additional test for grounding continuity to receptacles that they then list as self grounding. Self grounding receptacles have a spring in the yoke that maintains contact with the mounting screw. The screws shipped with those receptacles are plated to resist corrosion.
If you search I-zheet M'drurz other postings you will see he has no respect for the safety codes of any craft and that includes electricity. He knows more than everyone else, just ask him and he will tell you that anyone who disagrees with him is an idiot. But since our man Tom P says that ULC is full of hooey I guess that settles it. It's your home friend so you choose which advice you want to follow. It both cases the advise is legally worth exactly what you payed for it.
As to what qualifies me to give advice on this topic I'm an electrician with over thirty years in my craft and I have thirty five years of service as a volunteer fire fighter all of that in fairly busy suburban companies. I have carried out the dead several times and some of those were killed by fires of electrical origin.
-- Tom H
If the cable has a bonding strip inside the armor it is listed by electrical testing laboratories as suitable to serve as an Equipment Grounding Conductor (EGC). You do need to use the connectors that are listed for use with type AC cable. Those connectors must be made up tight enough to bond to the metal box. Do not try to use the bonding strip as a conductor within the box. There are regional preferences for how to treat the bonding strip at the cut end of the cable armor but testing done by Underwriters Laboratories showed that the different techniques had no effect on the impedance of the EGC pathway. You can cut the bonding strip off flush with the cable end, fold it back over the end, or wrap it around the end after installing the anti short bushing so that it holds the bushing in place. Which one you do is a matter of personal preference.
Since the cable has been tested and found adequate as an EGC there is no need for Ground Fault Circuit Interrupter (GFCI) protection of the cable run but GFCI protection may be required for receptacle outlets in a garage under the locally adopted electric code.
If the receptacles you use are not listed as self grounding by an electrical testing laboratory then you must bond the green screw of the receptacle to the box with a short piece of wire by using a machine screw into a tapped hole in the box. Sheet metal screws may not be used for that purpose. Alternatively you can use a listed grounding clip that you force onto the lip of the box after scraping away any non conductive coatings such as paint or plaster.
-- Tom H
Isn't the shield (casing) the ground?
Probably because shielded cable and metal boxes are not required in Calgary, so without insisting on a ground screw connected to a ground wire, there's no assurance that things are done properly.
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