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#83766 - 02/21/03 12:38 AM Anti-Short Bushings not required for MC Cable
Joe Tedesco Offline
Member

Registered: 10/07/00
Posts: 3325
Loc: Boston, Massachusetts USA
NEMA ENGINEERING DEPARTMENT BULLETIN No. 90
August 14, 2002

Use of Anti-Short Bushings for Terminating Type MC Cable

There has been much confusion within the Installation and Inspection communities regarding the use of anti-short bushings for terminating Type MC cable. The confusion stems from the fact that some MC cable manufacturers include anti-short bushings with their cable.

The inclusion of anti-short bushings with coils or reels of MC cable is based on historical practice relating to the
requirements of 320.40 of the NEC, which mandates the use of anti-short bushing or its
equivalent protection for Type AC Cable
Fittings used with Type MC Cable are required to be listed per 330.40 of the NEC.

NEMA supports the use of listed fittings for MC Cable. The design of these fittings may or may not include an insulated throat however, they are required to be provided with a smooth, rounded end stop so that the metal sheath of the cable will not pass through and the wires will not be damaged
in passing over the end stop.

Whether or not an insulated throat is part of the listed product, these listed MC fittings do not require an additional anti-short bushing. Anti-short bushings that may
be supplied by MC Cable manufacturers are for optional use by the installer, however they are not required.

ROP #7-116 from the May 2001 Report on Proposals (ROP) for the 2002 NEC was a proposal seeking to require anti-short bushings on all MC Cable termination installations.

The following is an excerpt from the Panel statement rejecting the proposal:

Anti-short bushings are not required for Type MC cable in accordance with the listing for the product. The termination fittings approved for use with Type MC cables are designed such that the wires will not come in contact with the cut edge of the armor; the throat of the fitting is small enough to prevent contact with the armor. Type MC termination fittings perform the same function for Type MC cable as Type AC terminations plus the anti-short bushing do for Type AC cable.

NEMA supports the uniform adoption and enforcement of the NEC and recommends that local Authorities Having Jurisdiction follow the requirements of NEC Section 330.40, Boxes and Fittings for MC Cable. Section 330.40 requires that the fitting be listed, but does not mandate the use of an anti-short bushing.
www.nema.org
_________________________
Joe Tedesco, NEC Consultant

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#83767 - 02/21/03 04:54 AM Re: Anti-Short Bushings not required for MC Cable
electure Offline

Member

Registered: 12/24/00
Posts: 4226
Loc: Fullerton, CA USA
A couple of years ago I contacted AFC (the manufacturer) re the bushings.
I was told that they were included only as an "added protection" for the cable terminations. The engineer said they were recommended, but not required...good enough for me. I still use them...S

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#83768 - 02/21/03 06:01 AM Re: Anti-Short Bushings not required for MC Cable
sparky66wv Offline
Member

Registered: 11/17/00
Posts: 2339
Loc: West Virginia
OK, who are you and what have you done with Joe?!?!?!?!
_________________________
-Virgil
Residential/Commercial Inspector
5 Star Inspections
Member IAEI

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#83769 - 02/21/03 07:47 AM Re: Anti-Short Bushings not required for MC Cable
ThinkGood Offline
Member

Registered: 08/07/02
Posts: 1084
Loc: Milwaukee, WI
Virgil:

ROTFL

Mr. Tedesco:

What cable types require the bushings? These are the "red heads," correct?

I recall a post on the board indicating that the bushing needs to be visible so the AHJ has no doubt that the bushing was installed.

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#83770 - 02/21/03 08:39 AM Re: Anti-Short Bushings not required for MC Cable
Roger Offline
Member

Registered: 05/18/02
Posts: 1779
Loc: N.C.
Thinkgood, that is the wording of 320.40 which is type AC. Type MC 330.40 does not require these.

Roger

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#83771 - 02/21/03 06:28 PM Re: Anti-Short Bushings not required for MC Cable
Joe Tedesco Offline
Member

Registered: 10/07/00
Posts: 3325
Loc: Boston, Massachusetts USA
OK, now I understand sparky66wv's post above:
OK, who are you and what have you done with Joe?!?!?!?!
 Quote:
It merely means to point out that it is uncharacteristic of you to point out
where the code has "lightened up" on an issue, especially without sounding
to be against said relaxation of code. I would expect you to be the one to
argue "110.3(B) Installation and Use. Listed or labeled equipment shall be
installed and used in accordance with any instructions included in the
listing or labeling" rather than be the one to point out the converse. It
is more characteristic of myself to point out flaws in the code than it is
of you. Therefore, I playfully said what I said, meaning that you have
apparently been kidnapped and replaced by an evil twin.


Is Type MC Cable used in WV?




[This message has been edited by Joe Tedesco (edited 02-22-2003).]
_________________________
Joe Tedesco, NEC Consultant

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#83772 - 02/21/03 08:49 PM Re: Anti-Short Bushings not required for MC Cable
SvenNYC Offline
Member

Registered: 08/19/02
Posts: 1685
Loc: New York City
Required or not, I'd still use those red bushings - they're damned cheap and sold by the bagfull!

There's no such thing as too much protection.....

Good thing now I also know there's a specific connector for type MC cable. I thought MC and BX cable connectors were interchangeable - the DIY books never point THAT out!

[This message has been edited by SvenNYC (edited 02-21-2003).]

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#83773 - 02/21/03 11:25 PM Re: Anti-Short Bushings not required for MC Cable
sparky66wv Offline
Member

Registered: 11/17/00
Posts: 2339
Loc: West Virginia
Yes, Joe, we use it on commercial jobs and when I have fluorescent lay-ins or for HVAC circuitry.

I always install the bushings, although I have seen those who did not, and I have mistakenly thought it would be a violation.

Of course, I just call MC Cable "BX".

[This message has been edited by sparky66wv (edited 02-22-2003).]
_________________________
-Virgil
Residential/Commercial Inspector
5 Star Inspections
Member IAEI

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#83774 - 02/22/03 10:04 AM Re: Anti-Short Bushings not required for MC Cable
electure Offline

Member

Registered: 12/24/00
Posts: 4226
Loc: Fullerton, CA USA
I got blasted on this by an inspector in San Diego, in pre-ECN days.
She made us cut the shear panel, replace the connectors and install bushings on an existing installation.
Then, the shear panel had to be repaired, per their other inspector.
In all, it cost about $800 or so.
That's just another reason I'm glad you're all here ...S

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#83775 - 02/22/03 10:44 AM Re: Anti-Short Bushings not required for MC Cable
iwire Offline
Moderator

Registered: 01/05/03
Posts: 4343
Loc: North Attleboro, MA USA
Whats a shear panel?
Bob
_________________________
Bob Badger
Construction & Maintenance Electrician
Massachusetts

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