when using those push on mc/bx connectors with the red things in top of them do you still need antishorts? The mc pushes in and the connectors push into the box. Does any one know? some people say you still need anti shorts some say you dont. I would not think you do because you are not screwing nothing in that could short out the cut part of the MC

Technically you dont need those bushings. They are not required but recommended.

Everyone has a different story on the antishorts. But since the MC comes with them in a little baggy and that they take no time to install, why not install them?

why not install them? they really don't take any time and they are free. the red insert does NOT protect the wires from the sharp edge of the sheathing, anti-shorts do. We use alot of those connectors... the only problems are when the guys don't use the anti-shorts.

[This message has been edited by ProCircuit (edited 04-28-2005).]

I did a little searching, bushings don't seem to be required for MC cable, but manufactures recommend it. And I agree with ProCircuit, the only time I have had a problem is when someone didn't use antishorts.

You can read it from one manufacturer here.
http://www.afcweb.com/pdfs/01catalog/01cat-p41-instal-instr.pdf

Go to page 55

Roger

[This message has been edited by Roger (edited 04-30-2005).]

where did you read that you don't need them. Im just trying to prove someone wrong I myself always use them.

I think it was in EC magazine in the question and answer section. I wasnt advocating not using them. I would and do. I was just pointing out that there is no code requirment for them.

From NEMA;

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.

Distribution List:
Standards and Conformity Assessment Policy Committee
Codes and Standards Committee
NEMA Executive Staff


Roger

I believe in time we will see anti-short bushing required in Type MC and Type AC installations.

Where I live the inspector does require antishort bushings he checks for them. I think it is a good practice to use them anyway. I always do.

Welcome to ECN spark1051.



Then the question is there a local amendment that the inspector can cite?

Inspectors can not enforce the use of anti-short bushings with MC cable if there are no local amendments. The NEC does not have an anti short requirement for MC.

If you wanted to press the point you could print out the NEMA bulletin that Roger posted.

For what it's worth I use them too.

I use them on MC cable when I have them handy, but if I don't have one handy, guess what? I won't use one. Sometimes it just takes too much time to hunt around for a little piece of plastic that isn't required anyway.

Peter

if there are no NEC codes for mc cable then what cable do you need to use them on? Also what is the difference between MC and BX? Mc has ground and BX don't thats the only difference right?

You are required to use them on AC cable. See 320.40

Kdrifter, the difference in MC and AC is as follows. (From AFC)

Armored (Type AC) Cable Construction

As described by the National Electrical Code NEC® 2002 Article 320, armored cable Type AC is a “fabricated assembly of insulated conductors in a flexible metallic enclosure.”
Type AC cable is manufactured to UL Standard 4. It consists of 2 to 4 copper conductors in sizes 14 AWG to 1 AWG inside an interlocked metal armor of steel or aluminum construction.
Type AC cable can have no more than four insulated conductors plus a grounding conductor (for a total of 5 conductors only) and cannot be manufactured larger than 1 AWG per UL 4.
A 16 AWG aluminum bonding wire is inside of, and in physical contact with, the metal armor providing a low-impedance fault return path required for the operation of overcurrent protection devices. The bonding wire is unique to AC cable and allows the outer metal armor in conjunction with the bonding wire to be used as an equipment ground. It is important to remember that the bare bond wire is not an equipment grounding conductor. It is the bond wire that, in combination with the interlocked metal armor, provides a low impedance equipment grounding path. Each of the copper conductors is covered with a thermoplastic insulation (THHN with a 90°C rating) and are individually wrapped in a moisture resistant, fire retardant paper.
According to NEC Article 320.40, an insulated (anti-short) bushing is required when installing Type AC cable. It is installed at the time of termination and designed to protect the conductors from damage. AFC provides bushings in bags packaged with the cable.


Metal Clad (Type MC) Cable Construction

As described by NEC Article 330, Metal Clad Type MC cable is a “factory assembly of one or more insulated circuit conductors with or without optical fiber members enclosed in an armor of interlocking metal tape or a smooth or corrugated metallic sheath.”
Type MC cable is manufactured to UL Standard 1569. MC cables may have 1 or more solid or stranded conductors in sizes 18 AWG and larger. The number of conductors allowed in an MC cable is not restricted by UL. The conductors may be of copper, aluminum or copper-clad aluminum.
The metal armor may be a smooth tube, a corrugated tube, or an interlocked metal armor. AFC Cable Systems manufactures MC cable with interlocked metal armor and copper conductors.
The make-up of AFC’s 600 Volt interlocked armor MC cable consists of:

• Copper circuit and grounding conductors
covered with thermoplastic insulation
• An overall polypropylene cable assembly tape
• An outer galvanized steel or aluminum interlocked armor

Unlike Type AC cable, the armor of interlocked Type MC cable is not an equipment grounding means and Type MC cable requires a bare or green grounding conductor.


Roger



[This message has been edited by Roger (edited 05-01-2005).]

Here in the Phoenix, AZ metropolitan area we use a lot of mc cable. Our company uses the snap-tight mc connectors by Arlington industries exclusively. The labor savings alone make up for the cost. I remember a post a long time ago about this and someone copied 320-40 on it. I don't have the exact code on me but in there it states. "If the mc connector that you are using already has an insulated red throat. that protrudes past the head of the connector and that an inspector can visually see, than you don't need an anti-short". I believe that the type of mc connector that the originator of this topic is using has an insulated red throat.
My theory is why use an anti-short when it really is not doing anything in there. Like the first post states there is no clamp tightening down on the metal jacket. I leave the clear plastic around the conductors, then slide the connector over, snap the mc cable in the connector and then remove the clear plastic. So in essence, the clear plastic can serve as an anti-short.

The purpose of this strip is to short together the turns of the spiral wrap, so fault currents won't turn the armor into an inductor, which can cause major heating and even fire.