pipe vs. romex???

[Mister Kool]

Is wire pulled in pipe (conduit) safer than romex????

If so, then why is romex allowed in our homes but not our offices ?

 

[Dennis Alwon]

Is wire pulled in pipe (conduit) safer than romex????

If so, then why is romex allowed in our homes but not our offices ?

I believe part of that answer would come from the rating of the building. Some offices are allowed to use romex depending on the type of construction and how it is classified. Romex is toxic and would not be allowed in plenums. Many dropped ceilings are plenums in commercial buildings.

I guess if a fire started in a home there is usually fewer people that have to evacuate before the toxic fumes might have an effect on them.

I would say yes that pipe is safer if installed properly. There seems to be more room for error running conduit if workers forget to tighten locknuts, coupling, connectors, etc. NM cable of course relies totally on the egc for the ground.

 

[iwire]

Is wire pulled in pipe (conduit) safer than romex????

Probably all else being equal.

If so, then why is romex allowed in our homes but not our offices ?

NM is not prohibited from offices.

NM is prohibited when building codes require non-combustible construction.

It does not make much sense (at least to me) to require pipe and wire in a wood framed house.

I think a better question is why our homes can be made of combustible materials and are not required to have sprinkler systems.

The answer to that is most likely costs.

 

[RHaggie]

All things being equal is the problem. Generally speaking, bending pipe and jerking romex are two different skills that require different methods besides simply installing the material. Pipe work typically has J-boxes above the ceiling amd most NM uses switch and outlet openings for the what splices might be needed as the building is wired point-to-point. Wiring a stick frame with EMT takes precise drilling- done that more times than I can rememeber- and there are very few places a j-box can be legally set and to leave enough lumber to support the building. I have also wired a bunch of medium to very large homes and multi-family with NM. NM goes a lot faster because of the single circuit approach is straightforward...until you forget a homerun.

The best answer I have for the question is a proper EMT job is just as safe as a proper NM job. Loose EMT couplings and connectors will arc when a ground fault occurs and this could kindle a fire anywhere along the conduit run. Keeping a rat from chewing through the jacket is the only downfall that I can think of for NM. Just kill the rats when that appear.

Since there is so much more going on in a residential building per square foot than in a commercial/industrial with the same square footage, I think it is safer to wire with NM, unless the only experience the electrician has is in commercial wiring. At that point, all bets are off. Same goes for a 100% NM guy wiring a commercial building. The two are different animals.

 

[augie47]

conduit

conduit

In commercial (office) work, one other aspect to consider is the ease with which a circuit can be added or altered with a conduit system. A spare, or underfilled conduit can make adding a circuit far from the panelboard a breeze compared with having to run a new NM circuit.

 

[infinity]

Since NM is permitted in hung ceilings in other than one or two family dwelling it is for all intents and purposes banned in commercial construction.

 

[iwire]

it is for all intents and purposes banned in commercial construction.

Walls, stores without ceilings still fair game for NM.

Besides, here where I am they removed the 'above suspended ceiling prohibition.

 

[infinity]

I made a mistake in the last post it should have read:

Since NM isn't permitted in hung ceilings in other than one or two family dwelling it is for all intents and purposes banned in commercial construction.

 

[Mister Kool]

In commercial (office) work, one other aspect to consider is the ease with which a circuit can be added or altered with a conduit system. A spare, or underfilled conduit can make adding a circuit far from the panelboard a breeze compared with having to run a new NM circuit.

true statement
that goes for conduit in homes too
new circuits are pulled with ease

 

[Mister Kool]

Loose EMT couplings and connectors will arc when a ground fault occurs and this could kindle a fire anywhere along the conduit run.

that arc shouldnt kindle a fire cause the breaker should trip

wouldnt heat from an overload on nm burn the insulation thus resulting in a poss fire????
thanx for the post Haggie

 

[kid_stevens]

NM is pretty well resticted in the 2005 NEC Article 334 for construction types 3-4 & 5. Many places are highly restricted. I have seen many fires caused by overloaded NM. One house had over 80 burn marks up down and sideways where the cable was loaded too far, that house survived.

I have never experienced a fire in a conduit as the lack of oxygen stops the fire shortly after it starts or the breaker trips once the wire burns off the insulation and exposes the wire to the neutral conductor or the conduit's return path.

Conduit can be installed in any location so that is a plus.
MC can go anywhere NM goes plus more.
Conduit can be rewired or added to after the fact. NM with its complicated stapling and routing requirements can not even be removed and replaced easily while the wall is intact.

In New Mexico only dwellings, Multi Family Dwellings and structures 3 or less stories in height can have NM installed. In the 50 and 60s here a lot of houses and most Adobe houses or walls have conduit in them. The 70s brought Aluminum romex and the 80s brought Copper romex.

 

[iwire]

NM is pretty well resticted in the 2005 NEC Article 334 for construction types 3-4 & 5.

Actually you can use it in types I and II if the buildings themselves could have been types III, IV or V.

I have seen many fires caused by overloaded NM.

I disagree, in my opinion the fires where not caused by the NM.

The fires where caused by the overload and improper over current protection.

In New Mexico only dwellings, Multi Family Dwellings and structures 3 or less stories in height can have NM installed.

Are you on the 2005 NEC?

The three story restriction has been removed from the NEC.

 

[kid_stevens]

Not in New Mexico. It was added by the State code.

 

[stickboy1375]

NM with its complicated stapling and routing requirements can not even be removed and replaced easily while the wall is intact.

.

Depends entirely if your good or not... lets see you add a wall sconce with conduit after the walls are closed up...

 

[RHaggie]

that arc shouldnt kindle a fire cause the breaker should trip

Circuit brakers take time to operate. During that time, the arc can last plenty long to kindle a fire- kindle, not start a blazing inferno. If there is a draft across the spot, there could be problems. A lot of factors have to line up, granted.

Proper installation is the key. Both systems, properly installed are equally safe. That last statement has a period at the end. An overload that damages the wiring has already been revealed as a faulty installation earlier.

Safety was the original question, not future considerations. Adding a circuit to a conduit system IS easier if there is enough cross-sectional area left to not derate the capcity of every conductor in the conduit. I have seen many installations where not only were the conductors NOT derated, they were fully loaded and the conduits filled close to capacity. Then again, they may have been OK at construction and it was after the final that the monkeying around took place. That's the point. What is easier is often disquised as simply being lazy. Pulling a wire in an existing conduit has potential ramifiactions down the line that can change the original design to sub-standard.

Which brings us back to safety, doesn't it?
Conduit systems are easier to improperly alter later, making them less safe than originally constructed. NM systems altered after the construction have the better chance of being installed as originally constructed...generally speaking.

 

[cowboyjwc]

I think a better question is why our homes can be made of combustible materials and are not required to have sprinkler systems.

They're required here.

 

[kid_stevens]

Safety was the original question, not future considerations. Adding a circuit to a conduit system IS easier if there is enough cross-sectional area left to not derate the capcity of every conductor in the conduit. I have seen many installations where not only were the conductors NOT derated, they were fully loaded and the conduits filled close to capacity. Then again, they may have been OK at construction and it was after the final that the monkeying around took place. That's the point. What is easier is often disquised as simply being lazy. Pulling a wire in an existing conduit has potential ramifiactions down the line that can change the original design to sub-standard.

Which brings us back to safety, doesn't it?
Conduit systems are easier to improperly alter later, making them less safe than originally constructed. NM systems altered after the construction have the better chance of being installed as originally constructed...generally speaking.

The NEC says we don't have to build for the future but why not. I too have seen overloaded conduit fills. Hey all the WallyMarts built here in the last 5 years have 4 inch conduit filled to 80% some are Comm & Video and some are 120V Branch and light circuits.

As to adding a wall sconce after a the wall is up I snake MC all the time in Apartment buildings.

Hey cowboyjwc where is here? I want to live there.

 

[ceknight]

Depends entirely if your good or not... lets see you add a wall sconce with conduit after the walls are closed up...

Don't knock it 'til you've tried it. I've been known to slide a piece of conduit into wall cavities just to make the fishing go more smoothly.

 

[cowboyjwc]

Hey cowboyjwc where is here? I want to live there.

Southern Calif. It's mostly a local ordinance. We used to not put them in until 5000 sq ft, but now it's any residential. Some of the surrounding jurisdictions have had that requirement for years.

 

[kid_stevens]

I left San Diego in 98 for good. Finally someone is thinking!