Bonding of BX Sheath

M

mjc.coup

Member
Location
Canada
Occupation
Electrician
Here is the situation:
I am wiring 10 4X high bay lights (with cord end) for a barn using PVC octagon boxes as the junction box for each light. Between the octagon boxes I am running BX through the attic into the back of each octagon box. Each box will have 2 BX's (one coming from last light and one going to next light). If the BX sheath is bonded at the panel end am I right in thinking I do not need any ground bushings in the PVC octagon boxes as long as I use BX duplex connectors (that will continue the BX sheath bond)? By duplex connectors I mean BX connectors that accept 2 BX wires. In the past for just one wire I've bonded just one end of a BX and been fine but this is a bit different situation.
 
You're using the duplex BX connector to continue the continuity of the cables that are daisy chained together? What are you using for an EGC in the PVC boxes?
 
The bx's (AC90) have a separate bond in the wire to bond the equipment. It is separated from the sheath. I just wanted to be sure my thinking was correct because I thought it was a weird situation where the bx sheath isn't continuing except through the duplex connector which isn't bonded to each box. Therefore the bx sheath is now bonding the duplex connector.
 
I realize you're in Canada but here in the US standard type AC does not have a wire type EGC. It has a jacket that is the EGC along with a bonding strip within the cable. The bonding strip alone cannot be used as the EGC. In that case you would need a bonding bushing within the PVC box to connect to the EGC (cable armor) if a connection is required.
 
I don't think you can use BX with plastic boxes. I agree the duplex connector will work to preserve the continuity of the EGC which is the bx armor. But how will the lights that are connected to the cord and plug get grounded?

I don't know of any BX with a separate ground wire only the aluminum strip which helps to bond the bx armor but can't be used itself as an egc. Unless I am mistaken you could use MC cable.
 
Eddie702 said:
I don't think you can use BX with plastic boxes. I agree the duplex connector will work to preserve the continuity of the EGC which is the bx armor. But how will the lights that are connected to the cord and plug get grounded?

I don't know of any BX with a separate ground wire only the aluminum strip which helps to bond the bx armor but can't be used itself as an egc. Unless I am mistaken you could use MC cable.
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In Canada we use BX with an aluminum sheath and a separate bare copper bonding conductor (that runs with the other conductors inside the bx sheath). The sheath is used for protection only and always needs to be bonded, while the copper bond is for bonding the equipment.
 
In the US, you can use non-metallic boxes with armored cable if there are 'internal bonding means between all entries' (314.3) so in general, in the US you can't use non-metallic boxes with MC or AC cable, unless it is a specially designed box.

I don't know if there is a similar requirement in Canada.
 
I know in the Dominican Republic, they don’t run a ground to the light fixtures, but do for receptacles. Don’t know what code they use. Also they use small plastic tubing, and pull wires in it.
 
mjc.coup said:
I am wiring 10 4X high bay lights (with cord end) for a barn using PVC octagon boxes as the junction box for each light. Between the octagon boxes I am running BX through the attic into the back of each octagon box.
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NO! Either use a complete non-metallic wiring system (PVC conduit or NM cable with PVC boxes) or a complete metallic wiring system (type AC, MC or EMT conduit with steel boxes). None of this mix-and match junk. Sounds like a DIY special.

-Hal
 
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