bx

[stanzee]

if using two conductor bx with ground can you sleeve in to pvc than in to the cb panel about three feet of pvc

 

[noxx]

Re: bx

"bx" is a misnomer these days, the most recent incarnation of metallic cabling is "MC" cable. If you'll refer to the MC specific section of the 2002, you'll see that MC cable may be run "In any raceway". However, in this case your PVC sleeve does not constitute a raceway but is rather "mechanical protection" which is fine, provided the MC cable is secured properly and its' metallic jacket does not protude in the panel.

-Noxx

 

[charlie]

Re: bx

BX is type AC which was changed to require "an internal bonding strip of copper or aluminum in intimate contact with the armor for its entire length." 320.100

Type MC cable is very different from type AC cable.

 

[tom baker]

Re: bx

Charlie if you really want to start a debate, ask what is the proper way to terminate the internal grounding strip on AC cable in the connector.

And AC cable requires an antishort bushing, while MC does not.

 

[charlie]

Re: bx

Tom, I thought you were a nicer guy than that! LOL

The Type AC cable bonding strip was added to stop the fires that the "BX" was responsible for without the bonding strip. All it does is provide continuity so the sheath is treated the same as a metallic raceway. Using a listed connector is all that is required with Type AC cable. The bonding strip is not required to be terminated.

The anti-short bushing that is required for Type AC is due to the connector design. The Type MC connectors have a smaller opening that prevents the sheath from damaging the conductors, therefore, the anti-short bushing are not required.

 

[sparkmantoo]

Re: bx

they have a new type of connector that uses a push in type connector. i found that these provide a good amount of protection to the conductors when they pass through the connector throat. but, no matter what, i always use the "red heads" to provide that additional piece of protection and mind. also i wrap that bonding conductor around the exterior of the ac type cable for two reasons. first to secure that red head to the cable and two the inspector likes to see it to make sure you didn't cut it off for being in the way.

 

[iwire]

Re: bx

Originally posted by stanzee:
if using two conductor bx with ground can you sleeve in to pvc than in to the cb panel about three feet of pvc

IMO No, you can not do this, as already stated you must mean type MC or even Hospital grade AC cable.

Even though you have a grounding conductor to ground the load served, you still must ground or bond the cable armor itself just as with any metal raceway.

As an example of this look at Exception 1 of 314.3

2002 NEC

314.3 Nonmetallic Boxes.
Nonmetallic boxes shall be permitted only with open wiring on insulators, concealed knob-and-tube wiring, cabled wiring methods with entirely nonmetallic sheaths, flexible cords, and nonmetallic raceways.

Exception No. 1: Where internal bonding means are provided between all entries, nonmetallic boxes shall be permitted to be used with metal raceways or metal-armored cables.

Exception No. 2: Where integral bonding means with a provision for attaching an equipment bonding jumper inside the box are provided between all threaded entries in nonmetallic boxes listed for the purpose, nonmetallic boxes shall be permitted to be used with metal raceways or metal-armored cables.

By using a PVC sleeve I see no way to bond the armor.


By sparkmantoo

I wrap that bonding conductor around the exterior of the ac type cable for two reasons. first to secure that red head to the cable and two the inspector likes to see it to make sure you didn't cut it off for being in the way.

I also do it this way, but we could cut it off if we wanted to, and still be code compliant.

 

[definitive]

Re: bx

And AC cable requires an antishort bushing, while MC does not.

Ive looked for a referance to this and cant seem to find one. Could you point me in the right direction?

 

[iwire]

Re: bx

For type AC an insulating bushing is clearly required.

2002 NEC

320.40 Boxes and Fittings.
At all points where the armor of AC cable terminates, a fitting shall be provided to protect wires from abrasion, unless the design of the outlet boxes or fittings is such as to afford equivalent protection, and, in addition, an insulating bushing or its equivalent protection shall be provided between the conductors and the armor. The connector or clamp by which the Type AC cable is fastened to boxes or cabinets shall be of such design that the insulating bushing or its equivalent will be visible for inspection. Where change is made from Type AC cable to other cable or raceway wiring methods, a box, fitting, or conduit body shall be installed at junction points as required in 300.15.

But the same article for MC does not require an insulating bushing.

2002 NEC

330.40 Boxes and Fitting.
Fittings used for connecting Type MC cable to boxes, cabinets, or other equipment shall be listed and identified for such use.

 

[iwire]

Re: bx

There is also this that was posted at another forum, which I believe but have not checked it out with NEMA myself, there is a link to NEMA at the bottom that could be used to verify this.

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

[ May 11, 2003, 07:08 AM: Message edited by: iwire ]

 

[definitive]

Re: bx

Thank you!