Prohibiting MC Cable Use, Why?

[jtinge]

Don, I believe the OP was talking about local deviation from the NEC.

Yes, that was the basis for my original post. I suspect what Don described as fighting between pipe manufacturer's and cable manufacturers could play a part in some of prohibitions to using MC Cable by some towns, especially if there is any relationship between the manufacturers and the officials making the rules.

I have run across several electrical commission minutes for various towns that were debating the use of MC Cable. The tone of the discussion indicates a perception by the commission that MC cable is "not as neat as raceway", "it sags", "it leads to sloppy work", and "there are potential workmanship issues regarding terminations". A comment by a fire official noted concern that fire fighters might "hook and yank" sagging MC Cable. While the "hook and snag" concern may be valid, I don't see how it is specific to MC Cable. I think there are other permitted wiring systems that have a similar potential for "hook and snag" during a fire response; however, I don't see their use being debated or prohibited like MC Cable.

I haven't seen any real evidence of actual problems associated with MC Cable in general or for specific applications. It seems to me that some of the prohibitions to using MC Cable is based more on an emotional response or perception rather than documented evidence of it being an inferior wiring system.

 

[don_resqcapt19]

Don, I believe the OP was talking about local deviation from the NEC.

Yes, you are right and there may have been influence from installers in that local deviation. If the local people don't like the deviation from the national standard, they can elect new people to change the rules

 

[LEO2854]

The reason for my original post is because for the last 25 years, we've had an unwritten policy that MC Cable shouldn't be used at our facility. However, no one that I've asked can provide the rationale for our policy other than that's the way we've always done it. There are valid reasons for being more restrictive than the code such as operational constraints, environmental considerations, experience, etc, but I like to provide the rationale behind any restrictions we impose.

I'm guessing our restriction on the use of MC Cable may be because we require all premises wiring to be installed in raceways with wiring installed after the raceways are completed. Another reason might be the fact that we required EGC's to be pulled in with the other conductors and original BX cable didn't have a separate EGC, but that's not the case with MC Cable. The third reason might be the perception that MC Cable in an industrial facility was less tolerant to abuse than the other wiring methods we used, and we extended the requirement to use raceways in all of our facilities regardless of occupancy or use type.

I'm willing to bet that the origanal Electricians there just wanted to run pipe for everything because it takes longer and they did not want to work their way out of a job.

 

[Strathead]

Wow - interesting responses.
Following responses are based on my work is 99.99% industrial

I can absolutely guarentee that MC-HL (specifically) is a god-send here is the great north - far superior to any conduit system.

As for having the cables "blow up" when moving them in a cabinet - I don't know what to suggest.
Maybe, "Any wiring method, improperly installed, is a danger".

ice

In my opinion the "blow up" is more of a function of badly designed and installed connectors, being over tightened., or poor workmanship with prepping the end of the cable.

 

[Strathead]

Wow, no one else is will to step in to it. I will. In my opinion, between observing the places and specifications that don't allow MC, and one place I am fully familiar with the history of, (San Francisco), I believe it is 90% Union lobbying period. It is little different than not allowing paint rollers, or extra tool pouches or any of hundreds of other time, cost and expertise saving inventions. Think about it. The one group that truly benefits from a ban on MC is the well trained, fully qualified, proud, professional Journeyman Electrician (and subsequently the company that gets to charge his mark up). Please note that the beginning is sort of an attack on Unions, but the end certainly is an attempt pay homage to the quality that they used to represent.

 

[don_resqcapt19]

Wow, no one else is will to step in to it. I will. In my opinion, between observing the places and specifications that don't allow MC, and one place I am fully familiar with the history of, (San Francisco), I believe it is 90% Union lobbying period. It is little different than not allowing paint rollers, or extra tool pouches or any of hundreds of other time, cost and expertise saving inventions. Think about it. The one group that truly benefits from a ban on MC is the well trained, fully qualified, proud, professional Journeyman Electrician (and subsequently the company that gets to charge his mark up). Please note that the beginning is sort of an attack on Unions, but the end certainly is an attempt pay homage to the quality that they used to represent.

If only the union electricians benefit from the a ban on a cable wiring method, are you telling me that only union electricians can install conduit? All installers and all contractors benefit from these rules...the losers, if any, are the building owners.

 

[GoldDigger]

If only the union electricians benefit from the a ban on a cable wiring method, are you telling me that only union electricians can install conduit? All installers and all contractors benefit from these rules...the losers, if any, are the building owners.

The motivations are the same, but the lobbying power may be very different. 'Nuff said.

 

[tom baker]

I have also had it blow up as I was moving wires around in a junction box because either an anti-short bushing was not used or the proper connector was not used.

Antishorts are not required for MC, but they are for AC. NEMA as a technical paper on this but I can't find it. Good for a bar bet, though.

 

[tom baker]

I'm willing to bet that the origanal Electricians there just wanted to run pipe for everything because it takes longer and they did not want to work their way out of a job.

There was the same issue with EMT when it was available. Jack Bender invented the one shot and traveled the country promoting EMT. Eventually electricans gave up the hickeys they were using. Every wiring method has its place.

 

[Strathead]

If only the union electricians benefit from the a ban on a cable wiring method, are you telling me that only union electricians can install conduit? All installers and all contractors benefit from these rules...the losers, if any, are the building owners.

I definitely did NOT say that only the unions benefit from the ban. In fact, all good electricians benefit from the ban, and in my opinion, the only electrical Contractors who actually benefit from MC are the ones who either do sub, spec work, or under bid anyway.

What I stated was that the REASON for the resistance is Union lobbying. That is not the same thing. And for clarification I meant Union associated, so that would include NECA Contractors.

 

[iwire]

The motivations are the same, but the lobbying power may be very different. 'Nuff said.

Very well put.

 

[iwire]

Yes, you are right and there may have been influence from installers in that local deviation. If the local people don't like the deviation from the national standard, they can elect new people to change the rules

Don that is a real cop out.

There is no way the general voting public votes based on what to them would be obscure code rules.

Let's step back into the real world and out of the theroretical one.

 

[jtinge]

So I'm guessing from the last few posts that there are vaild reasons for banning wholesale use of MC Cable? I'm ok with that, if there are good reasons to do so. I just haven't seen any presented in this thread.

 

[Strathead]

So I'm guessing from the last few posts that there are vaild reasons for banning wholesale use of MC Cable? I'm ok with that, if there are good reasons to do so. I just haven't seen any presented in this thread.

I think you are guessing wrong. The reasons are job security, and pride in workmanship mostly . The only "valid" reason and it was presented by someone else already. IMO for a customer perspective is ease of upgrade. The ability to add circuits change circuits etc with less time and effort, but it would take a lot of upgrading to offset any cost savings. Personally , I would prefer to run conduit with lined up coupling and perfectly executed bends all day long, but I wouldn't generally approach a design build to a customer that way. So bottom line, if your company is OK with paying the extra, please don't discourage them.

 

[growler]

Antishorts are not required for MC, but they are for AC. NEMA as a technical paper on this but I can't find it. Good for a bar bet, though.

It's not that I don't trust you and I have seen this other places.

Why do they include a bag of antishort bushings when you buy a roll of "MC" cable? I'm pretty sure they come from the manufacturer that way.

So I use them because it's better to be safe than sorry.

 

[jim dungar]

The reasons are job security, and pride in workmanship mostly . The only "valid" reason and it was presented by someone else already.

As far as skill and pride go, my hat is off to those that install MC and make it look good. It seems to be a whole lot harder than simply putting in a clip every ten feet.

Sloppy and ugly can be done with any wiring method.

I know of at least one major food manufacturer that no longer allow 'pipe and wire' on their production floor. If ain't cable, it ain't going in. In their mind it is too hard to control the inside of raceways.

 

[petersonra]

I know of at least one major food manufacturer that no longer allow 'pipe and wire' on their production floor. If ain't cable, it ain't going in. In their mind it is too hard to control the inside of raceways.

difficult/impossible to clean and tough to keep the vermin out.

its something a lot of food and drug people have been wondering about for some time.

no good answers considering how much conduit there is in most such plants already.

 

[tom baker]

It's not that I don't trust you and I have seen this other places.

Why do they include a bag of antishort bushings when you buy a roll of "MC" cable? I'm pretty sure they come from the manufacturer that way.

So I use them because it's better to be safe than sorry.

I asked the same question to the Armored Cable Mfg Rep on the CMP, Phil Simmons. He said its just the way the mfgs package the material and they may change it in the future.
The bag of connectors are typically for AC or MC.

 

[don_resqcapt19]

Are any of the code rules that ban MC left over from the original BX days, where there was no fault clearing path and sometimes it would glow red from the fault current flowing on the armor?

 

[GoldDigger]

... the original BX days, where there was no fault clearing path and sometimes it would glow red from the fault current flowing on the armor?

When you did not use the anti-short bushings?