bonding original BX

Hey Guys

Do you suggest that all the original BX electrical circuits with no bonding be protected with G.F.C.I./A.F.C.I. devices. Thanks

Most BX is bonded by way of the MC cable connectors. Without proper connectors, the installation of BX should be called out as deficient.

If you’re actually referring to “ungrounded” circuits (which are common in older BX applications), the answer is no. I do not recommend ungrounded circuits be AFCI or GFCI protected.

If the non-grounding type receptacles have been replaced with grounding type receptacles and are not grounded, then I do recommend adding GFCI protection as one alternative for correcting the improper installation.

It should also be marked as a non-grounded GFCI outlet. I personally have not seen this applied to AFCI yet.

Specifically what kind of BX installations (type AC cable) are not grounded?

[FONT=Times New Roman][size=3]Exactly the Original Aluminum BX that I saw had a strip of aluminum that we used to fold back over the Anti short and we made sure the BX connector clamp was tightened on it . This connector was fastened to the box with lock nut .

Before this it was steel BX and this had a small wire that did the same thing .


Thanks for the input, however, is the BX cable or case considered a satisfactory ground even with the correct connectors, can it handle a 20 amp. short? There is no bonding strip in original BX as in newer AC cable ( even though that supplied strip in AC seems undersized in case of an appliance shorting out on its metal case), so if damaged, as much of it is when pulled through walls, will it overheat, break. These thoughts are what make me feel GFCI protection labeled as non grounded receptacles would be the safest condition. Im not trying to beat this subject just searching for an overall liability safty net. Thanks again

The strip in modern (since the late 1950’s) AC cable is only there to provide a straight path for the fault current to flow on the metallic cable jacket. It is not inteneded to carry all of the fault current. Even if it’s broken in places within the cable it will still serve it’s purpose to connect together the individual helical windings of the jacket. As long as it’s properly terminated in connectors listed for grounding it should safely carry any fault current imposed upon it.

Thanks Robert for that information, I can agree on the strip in AC working with the metallic jacket to get the fault current back to the transformer creating a path with less resistance then ones body. What are your thoughts on GFCI protection on original BX with no strip, because many of the houses Im in were built in the 1945 era, in the after war boom when alot of families moved from the city out to the country areas. Also there are many crawlspaces in this area where this BX is very rusted creating way to much resistance. I always call out the rusted BX and poor connections when visible but nobody including myself is gonna pull out insulation to evaluate all the BX. Possibly I am overthinking this, well most likely I am as its 6 am. I just believe bonding saves people grounding saves appliances, at 15-20 amps. Thanks again

The GFI protection would be required if the receptacles have been changed to 3 prong.

Jim, isn’t that making an assumption that the jacket of the cable doesn’t qualify as an EGC?

The jacket does not qualify as a EGC as far as I have researched in the past, once spread apart the jacket its approx. equal to a 16 or 18 gauge wire. Ill stick with upgrading all receptacles to three prong grounded type/ GFCI protected and being correctly labeled

I fully understand how a GFCI works and am having a tough time getting my head wraped around installing GFCI receptacles to an ungrounded BX is going to help anything. Unless you are talking about installing a GFCI breaker at the service panel. If you test a GFCI receptacle in an ungrounded circuit they do not trip.

You may want to review just how a GFCI actually works.

They do not need a grounded circuit to function as intended.

They do not test with a simple 3 light tester because those $8 devices required an earth ground to function.

If you want to go through the trouble you can construct an adapter with a long pig tail on the ground pin so you can hook it to a near by grounded pipe.

Correct GFCI protection should be installed in knob and tube wiring also, again with no ground.

I don’t mean to derail this thread but I have a related question. Is installion of BX cable to a plastic box a defective installation? Never heard this before but someone stated it the other day. Is it defective in some circumstances only?

I dont think BX or AC to a plastic box meets codes and would be in the installed by an amateur section of a report. you would prob have to drill the plastic box to retrofit the cable connector and that is not what they were manufactored for. The metal box is part of the bonding in most cases. I have never seen it done where at least is was visible.

I dont believe plastic boxes were manufactored for BX or AC cable nor would it pass a code inspection. I would call it out as it would be difficult to see how it was rigged without removing the receptacle, not saying that rigging it is ok.

Generally this is a problem, but there are exceptions.

**[FONT=Times-Bold][size=2]314.3 Nonmetallic Boxes. **[/size][/FONT][FONT=Times-Roman][size=2]Nonmetallic boxes shall be permitted
only with open wiring on insulators, concealed knoband-
tube wiring, cabled wiring methods with entirely nonmetallic
sheaths, flexible cords, and nonmetallic raceways.
[/size][/FONT]*[FONT=Times-Italic][size=2]Exception No. 1: Where internal bonding means are provided
between all entries, nonmetallic boxes shall be permitted
to be used with metal raceways or metal-armored
Exception No. 2: Where integral bonding means with a
provision for attaching an equipment bonding jumper inside
the box are provided between all threaded entries in
nonmetallic boxes listed for the purpose, nonmetallic boxes
shall be permitted to be used with metal raceways or metalarmored

Interresting seems like alot of work to use plastic as a type of splice box to pass through but im sure it has its applications