John120/240
Senior Member
- Location
- Olathe, Kansas
Recent threads have brought up the prohibition against accepted wiring methods in different occupancies. No AC or MC for example. What would be the rationale ?
Prohibited methods
- Thread starter John120/240
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petersonra
Senior Member
- Location
- Northern illinois
- Occupation
- engineer
why does Chicago ban romex in single family houses?
- Location
- New Jersey
- Occupation
- Journeyman Electrician
It's simply a design issue where a designer feels that some wiring methods are better than others. It's the person who's paying more money for those "better" wiring methods that should be concerned.
- Location
- Wisconsin
- Occupation
- PE (Retired) - Power Systems
Among other (e.g. labor) reasons, is the penchant for rodents to gnaw on the type of PVC used in electrical wiring insulation.
petersonra
Senior Member
- Location
- Northern illinois
- Occupation
- engineer
are there no rats in the rest of the country?
- Location
- New Jersey
- Occupation
- Journeyman Electrician
I would guess that NYC has millions of rats and they allow AC, MC cable, and for single family dwellings NM cable.
fmtjfw
Senior Member
- Location
- Fairmont, WV, USA
History?
History?
Chicago, the city, burned down.
History?
Chicago, the city, burned down.
zbang
Senior Member
- Location
- Roughly 5346 miles from Earls Court
Definitely an electrical fire
(San Francisco burned down once before, but AFAIK they still allow NM)
mjf
Senior Member
The sheathing gets damaged installing it in all that required conduit?:angel:
SceneryDriver
Senior Member
- Location
- NJ
- Occupation
- Electrical and Automation Designer
Conduit costs more labor time to install, and employs more skilled people. The unions are very strong in Chicago. Not trying to start a flame war; that's how the local amendment to code was explained to me when I lived and worked in Chicago. The prohibition on Romex also extended to the Chicago suburbs as well, as far as I could ever tell.
Personally, I like conduit. Easier to modify and add a circuit later, without ripping open the walls.
The point about rodents chewing on the insulation isn't unfounded, however. Maybe the NYC rats haven't developed a taste for PVC insulation yet
SceneryDriver
petersonra
Senior Member
- Location
- Northern illinois
- Occupation
- engineer
It even extends into Lake County.
Oddly though, some places seem to have at least some exceptions for remodeling or repairs. Guess the rats know not to eat Romex used in repairs and remodels.
- Location
- Placerville, CA, USA
- Occupation
- Retired PV System Designer
Fishing EMT through walls does get tedious.
Sent from my Droid Maxx
Sent from my Droid Maxx
ron
Senior Member
- Location
- New York, 40.7514,-73.9925
Only a change that occurred in the last .... ~10 years or so.
mivey
Senior Member
They would chew Armorlite MC as well since they like to grind their teeth down on it. I know they love aluminum and copper conductor too. Not sure what they would do with Duraclad but its not like it is very thick.
kwired
Electron manager
- Location
- NE Nebraska
But is easy to fish RMC?Fishing EMT through walls does get tedious.
Sent from my Droid Maxx
What change, the different wiring methods or there wasn't any rats until about 10 years ago?
- Location
- Wisconsin
- Occupation
- PE (Retired) - Power Systems
renosteinke
Senior Member
- Location
- NE Arkansas
I will address two questions - the OP's, and the later raised issue of Chicago.
First off, we need to hop into the 'way back' machine a bit. While NM predates me (it came out in the 30's), well into the 60's I was present as wire manufacturers made specific representations to UL, the IAEI, and the code panels as to the limited uses for which their products were designed. The manufactures leaned heavily on 'listing and labeling' to support the use of their products.
At the time, NM reps were adamant that their product was intended for housing alone, with it's limited conductors. The manufacturers had no problem with code provisions restricting the use to residences. It was touted as a necessary product for the rapid construction of housing for the "baby boom." That's why even today there's no '3-phase' NM, or any attempt to rate the stuff for higher voltages.
For the metal-jacketed cables, there was the question of whether the jacket was an adequate ground path. This was not just an academic concern; the GFCI had not yet been invented, and it was rare to find a ground wire in a system. Panels typically did not have a separate ground bar, nor were neutral bars always isolated from the case.
Metal-jacket cable makers took two approaches. The AC makers followed the model of metal flexible conduit in asserting that the jacket was good enough of a ground path - then proceeded to incorporate foil or wire strips in the jacket to ensure good bonding at connections.
The MC makers continued to assert the superiority of their product, with its' separate insulated ground wire. Naturally, such an arrangement might have provided surer circuit grounding, but left unaddressed the question of whether the jacket itself was properly bonded.
In the late 60's, the special needs of operating rooms began to attract the specific attention of the code panels. Eventually, the NEC incorporated the already standard practices. One of these practices was to ensure that everything conductive where explosive gasses might be present were very well grounded.
The 'health care conundrum' effectively limited you to either using pipe, or flex with a ground wire and supplemental box bonding. You could not use AC (because there was no separate ground wire) or MC (because the jacket was not effectively grounded). In the late 1990's we saw the introduction of "Health care MC" (which was technically AC with a ground wire) to chase this market.
Now- as for Chicago:
Forget the "Great Chicago Fire" of 1871. Instead, look to the Columbian Exposition, held in Chicago in 1893. It was at this 'worlds fair' that electricity made its' premier. All manner of amazing uses of electricity were demonstrated. One result was a very large number of fires - some quite catastrophic. The Expo led directly to both Chicago's fire codes and the creation of UL. One of UL's primary mandates was to develop standards for the safe use of electricity.
Thus, it's no accident that Klein pliers, Benfield benders, and "Chicago benders" all came out of Chicago.
Chicago had codes long before everyone else discovered them. Chicago might be forgiven if they feel that, since they were there first, everyone else ought to follow their example.
The fact is, even the NEC has mixed feelings about NM. First they expand the places where you can use it, then they restrict it. Before 1999, NM was both allowed in damp locations, and it could be installed without devices specifically touted as protecting us from damaged cables (AFCI's). Since then, code panels have expanded NM into commercial spaces- while making nearly every existing home's use (crawlspace) illegal.
Maybe Chicago has been right all along.
First off, we need to hop into the 'way back' machine a bit. While NM predates me (it came out in the 30's), well into the 60's I was present as wire manufacturers made specific representations to UL, the IAEI, and the code panels as to the limited uses for which their products were designed. The manufactures leaned heavily on 'listing and labeling' to support the use of their products.
At the time, NM reps were adamant that their product was intended for housing alone, with it's limited conductors. The manufacturers had no problem with code provisions restricting the use to residences. It was touted as a necessary product for the rapid construction of housing for the "baby boom." That's why even today there's no '3-phase' NM, or any attempt to rate the stuff for higher voltages.
For the metal-jacketed cables, there was the question of whether the jacket was an adequate ground path. This was not just an academic concern; the GFCI had not yet been invented, and it was rare to find a ground wire in a system. Panels typically did not have a separate ground bar, nor were neutral bars always isolated from the case.
Metal-jacket cable makers took two approaches. The AC makers followed the model of metal flexible conduit in asserting that the jacket was good enough of a ground path - then proceeded to incorporate foil or wire strips in the jacket to ensure good bonding at connections.
The MC makers continued to assert the superiority of their product, with its' separate insulated ground wire. Naturally, such an arrangement might have provided surer circuit grounding, but left unaddressed the question of whether the jacket itself was properly bonded.
In the late 60's, the special needs of operating rooms began to attract the specific attention of the code panels. Eventually, the NEC incorporated the already standard practices. One of these practices was to ensure that everything conductive where explosive gasses might be present were very well grounded.
The 'health care conundrum' effectively limited you to either using pipe, or flex with a ground wire and supplemental box bonding. You could not use AC (because there was no separate ground wire) or MC (because the jacket was not effectively grounded). In the late 1990's we saw the introduction of "Health care MC" (which was technically AC with a ground wire) to chase this market.
Now- as for Chicago:
Forget the "Great Chicago Fire" of 1871. Instead, look to the Columbian Exposition, held in Chicago in 1893. It was at this 'worlds fair' that electricity made its' premier. All manner of amazing uses of electricity were demonstrated. One result was a very large number of fires - some quite catastrophic. The Expo led directly to both Chicago's fire codes and the creation of UL. One of UL's primary mandates was to develop standards for the safe use of electricity.
Thus, it's no accident that Klein pliers, Benfield benders, and "Chicago benders" all came out of Chicago.
Chicago had codes long before everyone else discovered them. Chicago might be forgiven if they feel that, since they were there first, everyone else ought to follow their example.
The fact is, even the NEC has mixed feelings about NM. First they expand the places where you can use it, then they restrict it. Before 1999, NM was both allowed in damp locations, and it could be installed without devices specifically touted as protecting us from damaged cables (AFCI's). Since then, code panels have expanded NM into commercial spaces- while making nearly every existing home's use (crawlspace) illegal.
Maybe Chicago has been right all along.
mivey
Senior Member
black+white+red+blue with bare ground is available.
- Location
- New Jersey
- Occupation
- Journeyman Electrician
Yup, we use it quite often for 3?, 4W temp circuits.
kwired
Electron manager
- Location
- NE Nebraska
I can't recall ever seeing NM cable that was not rated for 600 volts, and have seen it used for three phase, even black, red, white, is permitted to re-identify the white if not used as a grounded conductor in such instance.
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