Anti short bushings

[obrianjo]

I always use anti short bushings (red heads) when installing MC. I have had debates on whether or not it is actually required. Is there an article that I missing?

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[infinity]

They are not required for MC cable. AC cable they are required.

Welcome to the Forum.

 

[obrianjo]

Thank you. So there is no article referencing installations shall be performed to manufacturers recommendations?

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[roger]

Thank you. So there is no article referencing installations shall be performed to manufacturers recommendations?

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Not for recommendations however, if there were instructions telling you to do so 110.3 would be the article.

Roger

 

[obrianjo]

I'll have to pay closer attention to the verbage on instructions from here on out. Thanks

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[Dennis Alwon]

From Nema http://www.bptfittings.com/Public/D...- Use of Anti-Short Bushings for MC Cable.pdf

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.

 

[obrianjo]

Excellent info...thank you

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[kwired]

From Nema http://www.bptfittings.com/Public/D...- Use of Anti-Short Bushings for MC Cable.pdf

Makes me wonder why it is still required for AC cable. Most of us use the same connectors for either cable type, and the chance of the edge of the cut sheath damaging the conductors is about the same for either cable type.

 

[macmikeman]

An mc cable can short to the armor when not using red heads, so now I always do , don't ask me how I know this, but coffee and rushing was highly involved.

 

[ActionDave]

I've only seen one MC that was shorted at the connector and it was at the mouth of the connector, not at the sheathing so a red head would not have made a difference.

 

[Little Bill]

I've only seen one MC that was shorted at the connector and it was at the mouth of the connector, not at the sheathing so a red head would not have made a difference.

What about a blonde?:angel: