AFCI branch circuit

[electricalperson]

About 60% of the population of the State of Illinois where the local codes require the use of EMT for dwelling units, that is assuming that an AFCI receptacle would be more cost effective than an AFCI breaker.
Don

why do they require emt?

 

[don_resqcapt19]

why do they require emt?

It is a safety issue. NM is a safe wiring method, but conduit is safer.
If you compare the fire cause statistics for that area with the rest of the country, you will find that they have about 75% less fires that are said to be of electrical origin.
Don

 

[iwire]

If you compare the fire cause statistics for that area with the rest of the country, you will find that they have about 75% less fires that are said to be of electrical origin.
Don

Don, I have a real problem with that figure, there are a host of reasons why that result could be shown.

It to could be very simply that the Chicago Fire Dept does a better job of determining the cause of fires instead of just saying 'It's Electrical"

The electrical fire rate for Europe is also far under the US rate and they use cable extensively.

I find it inconceivable that if that 75% number was believable that insurance companies would not be pushing for the elimination of NM. Insurance companies pay great attention to issues like this, they would not ignore it.

 

[iwire]

why do they require emt?

Many would say....including myself, that it has to do more with making work then it has to do with electrical safety.

Look into Chicago's history a bit, they have a very strong and organized labor force.

 

[Dennis Alwon]

When I worked in NYC they always said the union would not allow nm cable because it didn't require the labor that bx or mc required. I also heard that it was because of the high rodent poplulation eating through the nm cables.

In more recent years they have allow NM under certain conditions-- I have not worked in NYC in 30 years so I don't know the regulations now.

 

[don_resqcapt19]

Bob,
I think that there are a number of reasons, but there is no question in my mind that metal conduit with metal boxes is safer than NM with plastic boxes...75% safer not likely.
As far as the "make work" issue, we all get paid by the hour...so there is no reason for one labor group to support a "make work" rule. If you are saying others can't be trained to bend conduit, I don't agree with that either. The most likely reason is to limit the DIY work as the Chicago code does not permit any.
Don

 

[electricalperson]

Bob,
I think that there are a number of reasons, but there is no question in my mind that metal conduit with metal boxes is safer than NM with plastic boxes...75% safer not likely.
As far as the "make work" issue, we all get paid by the hour...so there is no reason for one labor group to support a "make work" rule. If you are saying others can't be trained to bend conduit, I don't agree with that either. The most likely reason is to limit the DIY work as the Chicago code does not permit any.
Don

thats a good point i never thought of that

 

[iwire]

but there is no question in my mind that metal conduit with metal boxes is safer than NM with plastic boxes...

I don't see how you are in a position to judge how safe NM is when you have not as far as I know lived in an area that uses it extensively.

I am not sure what you think is happening with modern NM methods inside walls.

75% safer not likely.

Not a chance.

As far as the "make work" issue, we all get paid by the hour...so there is no reason for one labor group to support a "make work" rule.

Don......we are paid by the hour and the more hours a job takes the longer people are on the clock. If you want to ignore that influence so be it, this is definitely not the forum for that discussion.

 

[don_resqcapt19]

Bob,

I don't see how you are in a position to judge how safe NM is when you have not as far as I know lived in an area that uses it extensively.

Actually I am about 100 miles from Chicago and NM is used here...you have to be about 50 miles closer to get to the "pipe" codes. There is no question that a metal raceway is safer than a plastic covered cable and nothing will ever change my mind on that. As far as what is happening look at the reports of trips on AFCIs ...a number of them have been traced to setting the NM staples too deep. Many of the fires cited by the AFCI people were traced to things like picture hanging nails being driven into the NM cable. Neither of these things occur on a "pipe" job.

Don......we are paid by the hour and the more hours a job takes the longer people are on the clock. If you want to ignore that influence so be it,

My point is that that applies to (and benefits) all sectors of the electrical industry, not just one. In other words if it takes me longer to wire a house using EMT, it will also take you longer.
As far as the way the work was, in the past, limited to one sector in the Chicago area, it wasn't by the code rules requiring the use of specific products, it was via the code enforcement process.
Don

 

[peter d]

There is no question that a metal raceway is safer than a plastic covered cable...

I agree 100% with that statement. Now, where we will likely disagree is HOW MUCH safer are raceway methods over NM? I would say they are not much safer for the added cost and labor.

You often use the cost-benefit argument against AFCI's. I would use the same argument against residential raceway methods- the added cost of raceway provides only a marginal improvement in safety.

In fact, since fire reporting statistics are so inaccurate and there is no proven method for determining fire origin, I would say the benefit of of metal raceways systems is unknown.

 

[don_resqcapt19]

Peter,

You often use the cost-benefit argument against AFCI's. I would use the same argument against residential raceway methods- the added cost of raceway provides only a marginal improvement in safety.

It is my opinion that there is a better cost benefit ratio for the EMT than there is for the AFCIs. Based on the 2008 exception to 210.12, CMP2 apparently agrees that EMT and other metal covered installation methods are safer than NM.

In fact, since fire reporting statistics are so inaccurate and there is no proven method for determining fire origin, I would say the benefit of of metal raceways systems is unknown.

As is any other electrical safety device or installation method.
Don

 

[GilbeSpark]

Running emt in a residential dwelling is definitely going to be safer than using just nm. You wouldn't worry about putting a nail through it when hanging a picture (or anything else on the wall...and unlike hvac and plumbing, electrical work is on EVERY wall of a house).

You'd also limit the shady diy work from a homeowner who doesn't care about electrical codes or understand fire safety. With NM it's easy to make a flying splice in a wall to add that outlet you've always wanted behind the table in the hallway. If it were ran in emt I doubt you'd see people cutting into a metal pipe for this. And if they did they'd almost certainly have to call someone qualified to come fix it after they cut into the wire and "for some reason the breaker won't reset".

I'm not at all saying emt is cost effective vs the safety gain, but it is safer no doubt.

Ok, now you all stop this crazy talk before someone from NC decides to adopt this change for the 2011 NEC!!!

 

[iwire]

With NM it's easy to make a flying splice in a wall to add that outlet you've always wanted behind the table in the hallway. If it were ran in emt I doubt you'd see people cutting into a metal pipe for this.

I have real doubts that requiring EMT would prohibit the unqualified from messing up a perfectly good electrical system.

Look at the pictures on these forums, there is one where someone peeled the back side off of a 2" GRC service riser so they could tap free power.

 

[don_resqcapt19]

Ok, now you all stop this crazy talk before someone from NC decides to adopt this change for the 2011 NEC!!!

I already have my proposal ready...but it calls for rigid

 

[danickstr]

years ago i lived in a rental house piped in rigid. In echo park area, CA

 

[iwire]

I already have my proposal ready...but it calls for rigid

Shoot........don't go halfway, I want PVC coated Stainless rigid with explosion proof boxes. :grin:

 

[danickstr]

then if we could only make ladies pass a safety exam before using a blow dryer, and wear required clothing.

 

[don_resqcapt19]

Bob,

I want PVC coated Stainless rigid

I have to wait on that one until I get my company going to manufacture that product:grin: maybe 2014
Don

 

[daver828]

210.12

210.12

Had an inspector here in NC who told me that 210.12 related to all lights and receptacles in a bedroom. When it was brought to his attention that the book read "outlets", he quickly gave a lecture about the word "outlet" referring to all electrical fixtures originating from the master bedroom, including smoke detectors. The only thing he backed away from was when a floodlight was switched from the master bedroom and the fixture was (obviously) not inside the bedroom itself.

 

[russ]

Sounds like you're inspector got it right. The arc fault code pertains to 120 volt 15 and 20 amp branch circuits supplying outlets in the bedrooms.
That could be receptacle outlets, fixture outlets, or smoke detector outlets.