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#190094 - 11/05/09 08:00 PM Sleeve over MC cable
SJT Offline
Member
Registered: 07/24/02
Posts: 241
Loc: PATCHOGUE, N.Y.
Could a short piece of EMT be used as a sleeve to protect MC cable. A two foot piece protects the MC cable which then is terminated to a hot water heater. I was going to tell the Electrician to Re-do it, but I wanted to throw it out there for a Code Interpretation.
Thanks
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#190095 - 11/05/09 08:57 PM Re: Sleeve over MC cable [Re: SJT]
KJay Offline
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Registered: 11/27/07
Posts: 763
Loc: MA, USA

If just a sleeve, then the way 300.15[C] is worded, itís okay to do this with any cable type as long as there are fittings on the ends of the EMT to protect the cable from abrasion. Iíve used those plastic push-on bushings made by Arlington for that purpose before.

But, at least IMO, if actually changing wiring methods I feel that at least a changeover connector on the end of the EMT should be used as allowed in 300.15[F]. This may be up for debate though.
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#190114 - 11/06/09 06:09 PM Re: Sleeve over MC cable [Re: KJay]
HotLine1 Offline


Member
Registered: 04/03/02
Posts: 6778
Loc: Brick, NJ USA
A little thinking on this:
What happens IF the EMT sleeve were to become energized? As I understand the OP, the EMT is basically 'floating', and therefore not bonded!

Just for my info, why would you protect MC cable into a hot water heater?

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#190119 - 11/06/09 08:06 PM Re: Sleeve over MC cable [Re: HotLine1]
SJT Offline
Member
Registered: 07/24/02
Posts: 241
Loc: PATCHOGUE, N.Y.
I agree. They should have ran the EMT to a junction box and then directly to the control box. The EMT is floating and I don't like it. Chances are the EMT will not get energized but ya can't tell the judge that.
Good Weekend
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#190122 - 11/06/09 10:07 PM Re: Sleeve over MC cable [Re: SJT]
leland Offline
Member
Registered: 08/20/07
Posts: 853
Loc: Lowell area, Ma. USA
I'm with HOTLINE. Why a sleeve anyway?
u,If it is there BOND it.
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#190129 - 11/07/09 07:17 AM Re: Sleeve over MC cable [Re: leland]
renosteinke Offline
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Registered: 01/22/05
Posts: 5316
Loc: Blue Collar Country
I can imagine circumstances where you might want to sleeve a piece of MC; perhaps there's a particular section that might be subject to damage, or that you want to 'keep out of the way' and lack support points. Finally, theres the issue of penetrations, especially where you want to allow for future replacement of the cable.

Indeed, you would have to use a sleve if you had multiple cables to address.

I'm not worried at all about the sleeve becoming energized. Here's why:

First, we are not required 'structural metal that is unlikely to become energized.'

Second, there is the jacket of the MC, which is bonded. If the EMT is going to become energized, don't you think that the electricity is most likely to originate in that MC?

If you're a purist, you could assemble a fitting to make a direct MC -> EMT transition. If you're worried about abrasion, a connector or coupling on the ends of the EMT can address that concern.

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#190141 - 11/07/09 12:12 PM Re: Sleeve over MC cable [Re: renosteinke]
KJay Offline
Member
Registered: 11/27/07
Posts: 763
Loc: MA, USA
300.10, exception,1 specifically allows "short sections" of raceway used as a sleeve for support or protection of cables to not be made electrically continuous.

I suppose it could be argued that "short sections" means raceways 24-inches or less, but not sure if that is an actual requirement.
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#190144 - 11/07/09 12:24 PM Re: Sleeve over MC cable [Re: KJay]
gfretwell Offline


Member
Registered: 07/20/04
Posts: 9039
Loc: Estero,Fl,usa
Ah the old question "How long is short"?

I think I have 15 year old discussions from Prodigy about that spinning on a hard drive somewhere.

Harold E probably remembers some of them. wink
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#190148 - 11/07/09 02:23 PM Re: Sleeve over MC cable [Re: gfretwell]
HotLine1 Offline


Member
Registered: 04/03/02
Posts: 6778
Loc: Brick, NJ USA
Before we wander to far from the OP....
Based on the OP, & how I envision what he described and IMHO, the wiring method perhaps should have been a raceway, not MC.

As to 'bonding' the EMT, it's not 'structural metal', it's a raceway. The short section is a gray area, as Greg said...define 'short'.

Again, IMHO a concern of phy. dam. to the MC? Terminate and go with a raceway.
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John
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#190152 - 11/07/09 06:19 PM Re: Sleeve over MC cable [Re: HotLine1]
Obsaleet Offline
Member
Registered: 04/05/03
Posts: 362
Loc: Pa
What about dissimaliar metals? I would just use and EMT connector to a threaded half coupling to a M/C connector remove the sheath and install. I have done this in commercial building were M/C is run in the ceiling then surfaced mounted down the wall.

Ob
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