NM home run to gas furnace

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Is it common practice for NM to run bare through a hole in drywall stud bay out to the furnace?

They guys I work with say they've had every inspector allow this install. I briefly skimmed article 334 but didn't catch anything specifically prohibiting it.

What I'm talking about is bare romex running outside the drywall to the furnace in a finished interior space. We've done the same with electric water heaters many times as well.

We're still in the 2008 NEC cycle here
 

LEO2854

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Ma
Is it common practice for NM to run bare through a hole in drywall stud bay out to the furnace?

They guys I work with say they've had every inspector allow this install. I briefly skimmed article 334 but didn't catch anything specifically prohibiting it.

What I'm talking about is bare romex running outside the drywall to the furnace in a finished interior space. We've done the same with electric water heaters many times as well.

We're still in the 2008 NEC cycle here
AS long as it is supported and not subject to physical damage it should be no issue.....
 

Dennis Alwon

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Chapel Hill, NC
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This will depend on the inspector, the length of wire and whether it is likely to get damaged. IMO, it should be sleeved in flex of some sort. Well, that's how we do it simply because it looks better and it protects the nm cable. I don't believe you will get everyone to agree on what the code states as it is subject to interpretation. Authority having jurisdiction has the final call on this.
 

infinity

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I agree also but if it is truly subject to physical damage then flex is not one of the permitted protection methods listed in 334.15(B). If it's exposed, secured and follows the surface of the building finish or on running boards then IMO it porbably not subject to physical damage.

334.15(B) Protection from Physical Damage. Cable shall be
protected from physical damage where necessary by rigid
metal conduit, intermediate metal conduit, electrical metal-
lic tubing, Schedule 80 PVC conduit, Type RTRC marked
with the suffix -XW, or other approved means. Where pass-
ing through a floor, the cable shall be enclosed in rigid
metal conduit, intermediate metal conduit, electrical metal-
lic tubing, Schedule 80 PVC conduit, Type RTRC marked
with the suffix -XW, or other approved means extending at
least 150 mm (6 in.) above the floor.
 

Dennis Alwon

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Art. 334.15 does show the methods for protection but I believe most inspectors would accept carflex (LFNC). I personally look at the degree of protection that is needed. Obviously if the protection is needed in a high traffic area where cars can hit it then you would need something else.

I see it this way- If I can use carflex to an outdoor heat pump then I should be able to use it to protect NM cable inside cabinets, closets etc. This area of the code will always, IMO, be subjective.
 

donaldelectrician

Senior Member
AS long as it is supported and not subject to physical damage it should be no issue.....



I will never accept NM through the wall and Landing on a Water Heater , or what ever . Strapped or unstrapped .

NM , should terminate in a box, switch if needed , and carflex or greenfield to the appliance . Cleaner job .

i believe the romex is run exposed at a lower height than permitted , I find that behind cabinets too .





Don
 

infinity

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Here in the southwest we normally set a box and receptacle, use an appliance pigtail out of the furnace. This provides a simple local disconnect for the furnace.

Are these furnaces listed for field installed cord and plug connections or do they come that way from the factory?
 

GoldDigger

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Placerville, CA, USA
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I have seen a lot if such installations, but no furnaces that came with cord attached.
Did not read a lot of installation instruction docs though.
Water heater, never.
 
On the projects(+35 years) in the South West that I have worked on this has been a coordinated effort between the HVAC and Electrical contractors. This has been the local installation method, as for being listed that would be the HVAC contractors responsibility and the inspection authorities interpretation based on documents available. The furnace installation falls under article 422. All of the furnaces I have seen do not come with a cord installed, I believe that is done this way so the furnace can be installed to local codes.

What is the installation method in your Area?

I am not saying this is the right or wrong way of doing it, just stating that this is the way it is done here.
This JMHO...PJHolguin

Are these furnaces listed for field installed cord and plug connections or do they come that way from the factory?
 

ActionDave

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Durango, CO, 10 h 20 min from the winged horses.
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Licensed Electrician
This will depend on the inspector, the length of wire and whether it is likely to get damaged. IMO, it should be sleeved in flex of some sort. Well, that's how we do it simply because it looks better and it protects the nm cable. I don't believe you will get everyone to agree on what the code states as it is subject to interpretation. Authority having jurisdiction has the final call on this.
It is funny, flex offers no greater flexibility in the code in context of "exposed to physical damage" than NM. People are uncomfortable seeing exposed romex though.

It's like seeing that hairy guy at the beach. You know the one I'm talking about. He's heavy set, has black hair on his head, chest, arms, legs, and back. If you were to shave him you could stuff a mattress......Dude! Put on a t-shirt. It won't change the reality of the situation, but at least I don't have to see it.
 

shortcircuit2

Senior Member
Location
South of Bawstin
Is it common practice for NM to run bare through a hole in drywall stud bay out to the furnace?

They guys I work with say they've had every inspector allow this install. I briefly skimmed article 334 but didn't catch anything specifically prohibiting it.

What I'm talking about is bare romex running outside the drywall to the furnace in a finished interior space. We've done the same with electric water heaters many times as well.

We're still in the 2008 NEC cycle here

According to 334.15(A) NM cable shall closely follow the building surface where exposed.

334.30(B)(2) allows unsupported lengths up to 4 1/2 feet if within a accessible ceiling.

So, with that I would say that what you have described is in violation of the code.
 
Good Morning Action,

What method do you use to hook up a gas furnace? The method I mentioned is approved per NEC article 422, in fact it was a test question when I took my NM journeyman's test.

I have worked in several other states besides NM, and they all have their way of connecting furnaces. I believe it is just one those area specific requirements.


That is definitely a New Mexico thing, at least out the four states that make up the four corners. I can't get away with it in CO, AZ, or UT.
 

mopowr steve

Senior Member
Location
NW Ohio
Occupation
Electrical contractor
Has anyone seen/heard something that stated nm exposed under 7' should be protected from physical damage?
Personnally I use EMT to box on furnace w/ switch and a throat bushing on top of EMT in basement.
 

ActionDave

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Location
Durango, CO, 10 h 20 min from the winged horses.
Occupation
Licensed Electrician
Good Morning Action,

What method do you use to hook up a gas furnace? The method I mentioned is approved per NEC article 422, in fact it was a test question when I took my NM journeyman's test.
I hard wire and use MC mostly. It has a better wow factor with customers and avoids that NM yuck reaction I mentioned in my previous post.

Furnace is not mentioned as one of the items in 422 that are allowed to be cord and plug connected is it?

I have worked in several other states besides NM, and they all have their way of connecting furnaces. I believe it is just one those area specific requirements.
New Mexico seems to have a preference for cord and plug connections. Don't know about the rest of the state but here close to the boarder they even like domestic water heaters hooked up that way.
 
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