FMC vs AC/BX

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Old 12-07-14, 05:32 PM
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FMC vs AC/BX

Can someone tell me if there is a difference in terms of code between Flexible Metal Conduit and Armoured Cable? I've got a very short run (about 2') of AC and I like the idea of an FMC rather than AC as it'll be easier to cut. It's just a run of 14\2.
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Old 12-07-14, 06:09 PM
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No differences for code, just different wiring methods with different rules to follow. If you want to use FMC, go ahead. While code does not require it for a 2' run, I would recommend pulling in a ground wire.
 
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Old 12-07-14, 06:38 PM
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Any chance I'll be able to just pull Romex through?
 
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Old 12-07-14, 06:49 PM
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Why are you pulling NM through the flex?
 
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Old 12-07-14, 06:53 PM
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Just looking for a simple way to guard the NM. I need to do a short run from a box to and external transformer. Transformer can't be covered, but AC needs to be protected. Easier to use the NM I already have.
 
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Old 12-07-14, 07:19 PM
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Neither AC or NM cable can be used outside. Is it just entering the transformer through the back from inside the house?
 
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Old 12-07-14, 08:52 PM
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It's not outside at all. It's a run from a wall box to an LED transformer/rectifier. It's on top of my cabinets. 120ac comes up from the basement to a wall switch. Switched 120ac up to above the cabinets where a transformer exists. Then the 12vdc back down to the leds undercabinet.
 
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Old 12-08-14, 05:12 AM
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If the NM is not subject to damage you can run it on the surface.
 
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Old 12-08-14, 05:57 AM
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Really? Could on top of a cabinet be concerned subject to damage?
 
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Old 12-08-14, 06:07 AM
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Cabinets

Is the top of the wall cabinets the usual 84 In. high?
 
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Old 12-08-14, 07:07 AM
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I would not consider the top of a cabinet to be subject to damage.
 
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Old 12-08-14, 07:59 AM
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One place is 84" and the other is probably 90" (we have 9' ceilings).

And I did email the city inspector to see what he would consider "subject to damage" since he's the one that ultimately signs the paper :-)
 
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Old 12-08-14, 02:39 PM
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It is pretty common to poke some Romex out of the drywall on top of the cabinets to power the light transformer. I don't expect there to be any problem from the inspector on this one.
 
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Old 12-08-14, 03:02 PM
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really? And I could get away without a junction box up there too then? Wouldn't I need some sort of strain relief to make sure the Romex doesn't get yanked or anything?
 
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Old 12-08-14, 03:13 PM
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Depends on whether or not the transformer itself is a rated j-box. Many have 1/2" KOs you can put the Romex clamp in.
 
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Old 12-08-14, 05:46 PM
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If you want to protect the cable with FMC, that is also fine. We do it all the time to protect cables in cabinets.
 
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Old 12-08-14, 06:24 PM
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Yeah this transformer has knock outs so that's covered with no problem. Still haven't heard back from the inspector. Maybe just have to call.
 
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