Why does non-metallic cable meet code?

[bchee]

I only recently started working with non-metallic, plastic sheathed wiring.
(I think the romex brand)

The sheath seems to be so easily damaged, I don't understand how this stuff is acceptable in most houses. Seems like even mild splinters can damage the sheath, and what about insects or rats chewing on it??

Is it correct that you can run it through holes in studs without any other protective tubing around it?

 

[CUSTOMMANCAVES.COM]

It has to be at least 1.25" in from the surface of the stud/joist. If you cannot meet this distance requirement, you must use a nailer plate.

Yes, "Romex" can be damaged easily, but if it is installed properly and to code, the chance of damaging it is minimal.

 

[kbs2244]

I am guessing you are used to EMT?
(Electrical Metallic Tube)

It is mostly a urban thing.
And that is because the early home lighting systems were gas lamps.

As I understand it the early lighting systems were gas lights.
There where pipes in the walls to bring the gas to the lamps.
When electricity came along, and people wanted to update, they pulled the wires through the old gas pipes so they wouldn’t have to tear up the walls.
And that started the tradition of putting wires in pipe.

A lot of early home wiring in basements and such was completely exposed wires.
But that got kind of dangerous and the code writers said it should be in pipe.

But outside heavy urban areas, Romex is king.

Like everything in construction, it has its rules.
Follow them and you will be safe.


BTW; industrial uses EMT just because of the danger of heavy stuff being moved around.
A bump into a pipe with a lift truck is not as dangerous as bumping into Romex.

 

[hofferwood]

You forgot "Knob and Tube"
Chuck

 

[bchee]

My house has BX, which I think is the same EMT. The wires are inside a corrugated metal conduit which is somewhat flexible. I wouldn't say I'm "used" to it, I have almost no electrical work experience.

I'm doing some DIY wiring in my kitchen; this NM just seems so fragile to me, I can't believe it is so widely used. As you're pulling it through the holes in studs, I don't see how it stands any chance.

It looks like something little creatures would love to chew on

 

[walrus]

My house has BX, which I think is the same EMT.

EMT is thinwalled pipe, that you pull wires into after its installed, not the same as bx

As you're pulling it through the holes in studs, I don't see how it stands any chance.

You can pull it thru wooden studs, metal studs take a special grommet. Critters might chew on it

 

[comedyman809]

if your house has little creatures chewing at things, maybe you will need an exterminator as well.

 

[Ford12508]

Romex in most homes is inside of the walls, and it is only exposed when the building is being, well, built. Otherwise no one ever sees it again unless refinishing a home or room.

 

[Grogan14]

The sheath seems to be so easily damaged, I don't understand how this stuff is acceptable in most houses.

You must have purchased an inferior brand of NM-B. Most are plenty resilient. In 20+ years of full-time residential electrical contracting, I've had one instance where the sheath tearing was an issue, and after getting numerous complaints, the supply never stocked that brand again. If what you have is so bad that you're worried about pulling it through studs, I suggest you take it back and complain.

Requiring homes to be wired in conduit is extreme overkill.

 

[CUSTOMMANCAVES.COM]

Requiring homes to be wired in conduit is extreme overkill.

But it makes future repairs/upgrades so much easier! I have a client whose office is a converted home. Place was built in the 40's or so(?). There is 3/4" conduit everywhere, including the low-voltage boxes. I assume this was a code requirement at one time. When he calls for a new phone, computer or TV drop, I fish/pull and am done in minutes.

If all new homes were done with conduit, I'd be a happy camper (no more crawling through attics!).

 

[kbs2244]

BX is a compromise.

It gives you the code requirement of a “metal sheathing” while giving the ease of install of Romex.

 

[Grumpy365]

NM cable, you may scrape up the sheathing, but the wire is still insulated and tuff as hell.

The code for stapling it seems messed up to me, but no one consulted me before making the decision.

(The logic is if it is stapled to a stud it is safe from damage, To me, you just put it where every person in the country is going to try to hang a picture, and you fastened it down so when you nail into it, it won't give. If you let it hang in the wall, even if someone was to try to nail it, it would bump out of the way.

 

[Norcal]

This thread seems like it should have come from Chicago not Texas.

 

[Grumpy365]

This thread seems like it should have come from Chicago not Texas.

I don't get it? whats with the geographical reference?

 

[Norcal]

I don't get it? whats with the geographical reference?

Chicago & it's suburbs do not allow NM cable, so EMT is used for residential.

 

[gdf_77]

Chicago requires a minimum of BX, last I had heard. There are other places as well. I worked as a factory rep in New Jersey that the requirement was no less than BX. There are other things that can be placed through out homes to ease in future repairs, NMT (smurf tube) is cheap and flexible.

 

[kbs2244]

Cook County, where Chicago is, has the strictest electrical code in the country.

I have seen the factory installed, internal wiring, in production equipment fail an inspection.
It was all inside the metal covers of the machine but it had to be torn out and rewired inside EMT.
This was in suburban Mt. Prospect.

 

[bchee]

This thread seems like it should have come from Chicago not Texas.

This house is in TX, but built in 1981. I guess back then the wiring was different.

 

[pstnbly]

Cook County, where Chicago is, has the strictest electrical code in the country.

I have seen the factory installed, internal wiring, in production equipment fail an inspection.
It was all inside the metal covers of the machine but it had to be torn out and rewired inside EMT.
This was in suburban Mt. Prospect.

I think that might have something to do with Mrs. O'leary's cow

 

[Norcal]

I think that might have something to do with Mrs. O'leary's cow

More like union "make work".

 

[kbs2244]

You are both right.
The fire gave the unions the reason to demand what some think are over the top safety rules.
It is all through the Cook County Building Code.
But I grew up with it, so I am used to it.