MC/AC Clamp in bracket boxes
- Thread starter Rick Haupt
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Okay, I just looked it up
Okay, I just looked it up
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
Okay, I just looked it up
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
wirestripper
Member
- Location
- Arkansas
"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." quote
Yes, exactly.
The way I can tell if it is a approved MC fitting is by looking for this throat design. The designs have improved, but some of the older fittings that require the bushing for MC are still in circulation for some reason. I ran into some last month.
IMO, MC sharps are even more damaging to the wire then the "AC" edges are, and the reason I believe the bushings are still used for "AC" is that the bushing keeps the end rounded and circular which makes the connector stronger and resistant to pull out's.
Anyway, it took some getting used to the code restrictions removal. MC cable is the low cost alternative to AC and it will likely be marketed until it is not, and I don't see any changes in that coming. This creates a problem in medical facilities where MC is used when AC is indicated by code and it is one of the things I always look for and often see.
Yes, exactly.
The way I can tell if it is a approved MC fitting is by looking for this throat design. The designs have improved, but some of the older fittings that require the bushing for MC are still in circulation for some reason. I ran into some last month.
IMO, MC sharps are even more damaging to the wire then the "AC" edges are, and the reason I believe the bushings are still used for "AC" is that the bushing keeps the end rounded and circular which makes the connector stronger and resistant to pull out's.
Anyway, it took some getting used to the code restrictions removal. MC cable is the low cost alternative to AC and it will likely be marketed until it is not, and I don't see any changes in that coming. This creates a problem in medical facilities where MC is used when AC is indicated by code and it is one of the things I always look for and often see.
wirestripper
Member
- Location
- Arkansas
"This creates a problem in medical facilities where MC is used when AC is indicated by code and it is one of the things I always look for and often see."
Before someone smacks me for the above statement, I actually do understand that MC can be used in hallways, waiting rooms and areas where patient care is not a concern. But anywhere that critical care is going on, or patients come into contact with electric power via medical devices such as pumps, heating equipment and even lamps, the MC cable cannot be used. There are a variety of issues that determine general patient care and critical care and if anyone needs my opinions on that I will be happy to write a few paragraphs.....
I figured I better get that out of the way.......
LOL....
Before someone smacks me for the above statement, I actually do understand that MC can be used in hallways, waiting rooms and areas where patient care is not a concern. But anywhere that critical care is going on, or patients come into contact with electric power via medical devices such as pumps, heating equipment and even lamps, the MC cable cannot be used. There are a variety of issues that determine general patient care and critical care and if anyone needs my opinions on that I will be happy to write a few paragraphs.....
I figured I better get that out of the way.......
LOL....
chicar
Senior Member
- Location
- Lancaster,Pa
There are some mc- ac connectors that do not need red heads.
fc
Senior Member
- Location
- New Jersey
wirestripper said:
You mean HCF cable not AC cable right?
Wirestripper. Plain Jane AC can not be used in patient care areas, it would have to be HCFC or HFC and then only for normal or equipment branch circuits unless one of the conditions of exception 3 of 517.30(C)(3) is applicable.
As an aside, there is a new MC that meets the criteria of 517.13(A) so MC will most likely become a common patient care wiring method if the price is right.
And one more thing, I get along very well with my inspectors, we have a mutual respect for one another.
Roger
As an aside, there is a new MC that meets the criteria of 517.13(A) so MC will most likely become a common patient care wiring method if the price is right.
And one more thing, I get along very well with my inspectors, we have a mutual respect for one another.
Roger
Chris, welcome to the forum, click on the link below and you will find the difference and much more information on MC and AC cable assemblies.
http://www.afcweb.com/pdfs/afcpocketguide.pdf
Roger
http://www.afcweb.com/pdfs/afcpocketguide.pdf
Roger
wirestripper
Member
- Location
- Arkansas
Not this again....LOL...fc said:
It took me a minute tolook all this back up and get the section numbers, but here it is.
Start at 517.13....it takes you to 250.118-8 and then to 320.108 and then to 250.4-A5 and B-4.
As you read, you will see that AC is acceptable and that HCF or whatever the mfgr decides to call it, is a hospital rated AC cable, usually paired with color coded connectors to satisfy inspectors for the most part and impress clients. It is expensive to buy it this way, so some of us by AC cable and hospital fittings and make sure the mfgr has this particular AC tested with the UL codes and approvals. But it is still AC cable in my opinion, and you can hire someone to paint stripes on it if you like.
I think it is important to note that the cable need only pass the grounding test and all you need to do is get the factory rep to fax the data to you if you need it for us inspectors. They do it all the time.
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wirestripper
Member
- Location
- Arkansas
"As an aside, there is a new MC that meets the criteria of 517.13(A) so MC will most likely become a common patient care wiring method if the price is right."
Yes, I heard about that stuff, but I have yet to see it. If it is true MC, then it would have a steel jacket. If it is aluminum with a stringer, then it seems to me to still be AC.
The problem with all these new designations is that it confuses everyone trying to discuss the issue. The way we have done it for decades has been to make sure the AC had a hospital rating. This entails a UL grounding test and they do it as a matter of course.
Pricing pressures often cause mfgs to put out a line of cheaper cable that they don't guarantee to be hospital rated, but it is still AC. So the code clarifies this by saying it must have hospital rated grounding fittings or really just rated grounding fittings and pass the grounding test.
Some MFGs have now specially labeled and named their various hospital grade products, and they are all based on the basic grades of AC but some have more frills and bells.
This is how I see it. To me, AC is AC and hospital rated AC is still AC until the code says otherwise. Then I'll call it something else and add one more term to my parts and pieces book that resides in my aching head.....
G'nite all.......
Yes, I heard about that stuff, but I have yet to see it. If it is true MC, then it would have a steel jacket. If it is aluminum with a stringer, then it seems to me to still be AC.
The problem with all these new designations is that it confuses everyone trying to discuss the issue. The way we have done it for decades has been to make sure the AC had a hospital rating. This entails a UL grounding test and they do it as a matter of course.
Pricing pressures often cause mfgs to put out a line of cheaper cable that they don't guarantee to be hospital rated, but it is still AC. So the code clarifies this by saying it must have hospital rated grounding fittings or really just rated grounding fittings and pass the grounding test.
Some MFGs have now specially labeled and named their various hospital grade products, and they are all based on the basic grades of AC but some have more frills and bells.
This is how I see it. To me, AC is AC and hospital rated AC is still AC until the code says otherwise. Then I'll call it something else and add one more term to my parts and pieces book that resides in my aching head.....
G'nite all.......
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wirestripper
Member
- Location
- Arkansas
roger said:Wirestripper, you really need to look closer at the difference between AC and HCF, there is more to it than just colors of the sheath or conductors. After you do, you will know why your statement above is wrong.
Roger
Well, if it has a aluminum shell and individually wrapped wires in a paper like substance, with a aluminum wire running the entire length, and is expensive, it is AC.
wirestripper
Member
- Location
- Arkansas
Roger, 250-118-8 clearly states that AC "type" cable meets the grounding standards required by the code.
Then it refers you back the the grounding section to illustrate why and I also take that to mean that the testing is rigorous.
When I ask the guy at the counter for hospital grade, he verifies it via fax and I get their best grade of AC, but they may in fact call it by a second desigation, and that is a fairly recent development. The code has yet to specify any of the new grades. So, a fax is sufficient for me to approve a AC installation where AC is used and I usually ask one simple question.
"Is that hospital rated AC and Fittings", freddy? I hope I don't hear "I dunno....." But it has happened....
Then it refers you back the the grounding section to illustrate why and I also take that to mean that the testing is rigorous.
When I ask the guy at the counter for hospital grade, he verifies it via fax and I get their best grade of AC, but they may in fact call it by a second desigation, and that is a fairly recent development. The code has yet to specify any of the new grades. So, a fax is sufficient for me to approve a AC installation where AC is used and I usually ask one simple question.
"Is that hospital rated AC and Fittings", freddy? I hope I don't hear "I dunno....." But it has happened....
wirestripper
Member
- Location
- Arkansas
I'm not a instructor. If I were, I would mention the new designations for this rated AC cable and tell them that the code has not yet confimed it and removed AC from the approved list by substituting another designation.
This will be the case until 2008, and we shall see what they do....
In the mean time, I have explained this many different ways and like most terminology arguments, you go with what you know.
This will be the case until 2008, and we shall see what they do....
In the mean time, I have explained this many different ways and like most terminology arguments, you go with what you know.
Wirestripper, you still have not accurately described the difference between AC and HCF, the sheath is only part of the equation in Patient Vicinity's.
There is no such thing as "Hospital Grade AC" although, it is a somewhat common term. I'll point it out tomorrow if you haven't found it by morning.
Hint, regular AC can be used above 7.5'
Roger
There is no such thing as "Hospital Grade AC" although, it is a somewhat common term. I'll point it out tomorrow if you haven't found it by morning.
Hint, regular AC can be used above 7.5'
Roger
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