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Discussion Starter · #1 · (Edited)
We're doing a lighting replacement project and am wondering if we have add a egc to the AC cable coming through the ceilings. It is stranded THHN inside a steel armored casing no bonding strip and is a heavy durable steel. Can someone confirm that BX has the old rubber and cloth insulation on the cable and AC has the tiny bonding strip ran through it?
 

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We're doing a lighting replacement project and am wondering if we have add a egc to the AC cable coming through the ceilings. It is stranded THHN inside a steel armored casing no bonding strip and is a heavy durable steel. Can someone confirm that BX has the old rubber and cloth insulation on the cable and AC has the tiny bonding strip ran through it?
That is just flex, not BX, so you need to run a ground wire.
 

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100% theres no bonding anything inside, the reason for such concern. I think if its kept under 6' we might be ok
No. You won't. The cable you are describing is not permitted as an EGC. At least, not for today's standards.

At 6' or less, attached to a properly grounded system, it might be ok... I won't bet my lunch on it though.


Pete
 

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art. 250.118 (5)

(5) Listed flexible metal conduit meeting all the following
conditions:
a. The conduit is terminated in listed fittings.
b. The circuit conductors contained in the conduit are
protected by overcurrent devices rated at 20 amperes
or less.
c. The combined length of flexible metal conduit and
flexible metallic tubing and liquidtight flexible metal
conduit in the same ground-fault current path does
not exceed 1.8 m (6 ft).
d. If used to connect equipment where flexibility is necessary
to minimize the transmission of vibration from
equipment or to provide flexibility for equipment that
requires movement after installation, an equipment
grounding conductor shall be installed.
 

· Electrical Simpleton
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So, maybe the manufacturers are covering their butts for (C)? Otherwise, I don't see anything that would require an EGC.
What the OP is describing may be "code worthy" in lengths under 6' but from my personal experience (seeing fires caused by BX cable) I wouldn't trust it.

I do not believe it is a reliable return path for fault current due to the seemingly high impedance.

Pete
 

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What the OP is describing may be "code worthy" in lengths under 6' but from my personal experience (seeing fires caused by BX cable) I wouldn't trust it.

I do not believe it is a reliable return path for fault current due to the seemingly high impedance.

Pete
Agreed but if it is a whip there should be no issue as the impedance on 6' is not very great. I have seen the old BX without the metal strip in it actually glow from a short that wouldn't trip the breaker
 

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Discussion Starter · #15 ·
What the OP is describing may be "code worthy" in lengths under 6' but from my personal experience (seeing fires caused by BX cable) I wouldn't trust it.

I do not believe it is a reliable return path for fault current due to the seemingly high impedance.

Pete
How many fires have you seen? I thought BX was safer than MC. Luckily there's class P ballast in them
 

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What the OP is describing may be "code worthy" in lengths under 6' but from my personal experience (seeing fires caused by BX cable) I wouldn't trust it.

I do not believe it is a reliable return path for fault current due to the seemingly high impedance.

Pete
I'll be a little more specific about my question (slight side step from the OP)...

If I were to make my own fixture whips with 3/8" FMC, with listed connectors, protect the conductors at 20A, and keep the length under 6', would I have to install an EGC in the whip?
 

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How many fires have you seen? I thought BX was safer than MC. Luckily there's class P ballast in them
3. I'm no forensic engineer but it isn't a stretch when you see the outline of the BX coils on a truss with the signature char marks.

Pete
 

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Agreed but if it is a whip there should be no issue as the impedance on 6' is not very great. I have seen the old BX without the metal strip in it actually glow from a short that wouldn't trip the breaker
I do actually agree with you.

Just saying... I wouldn't trust it... would I fail it on an inspection?

No. I have no code verbiage to do so.

Pete
 

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I'll be a little more specific about my question (slight side step from the OP)...

If I were to make my own fixture whips with 3/8" FMC, with listed connectors, protect the conductors at 20A, and keep the length under 6', would I have to install an EGC in the whip?
Sorry to say this... But, maybe. If the AHJ makes a determination that the FMC is installed to "provide flexibility for equipment that requires movement after installation" then yes an EGC would be required.

For a typical 2X4 lay in fixture I wouldn't see what I quoted as requiring an additional EGC.

Pete
 

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Sorry to say this... But, maybe. If the AHJ makes a determination that the FMC is installed to "provide flexibility for equipment that requires movement after installation" then yes an EGC would be required.

For a typical 2X4 lay in fixture I wouldn't see what I quoted as requiring an additional EGC.

Pete
Thanks. We just changed to the 2011 and the wording in the 2008 could be interpreted differently.

d. Where used to connect equipment where flexibility
is necessary after installation, an equipment
grounding conductor shall be installed.
Because of this wording, most EC's decided to run EGC's no matter what the circumstance.
 
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