Drop ceiling

[Fred B]

I'm not suggesting it, I'm saying it plainly.

334.30(B)(2) has an exception for securing NM cable that specifically mentions luminaires in an accessible ceiling.

It may not be 100% evident in all of the wording in every sentence, but at least in the intent there is a distinction between "exposed" and "exposed within a grid ceiling"

There are several key conditions to your referenced article. 1 only in relationship to "securing and supporting" of NM. 2 last point of securing by an "approved means" must be "not more than" 4.5 ft from last point of attachment to the equipment. 3 for allowance to make a connection of "luminaries or other peice of electrical equipment". 4 and probably the most important condition, only applicable to "in one, two, or multifamily dwellings".
I don't see your distinction to be evident from your reference to give a free for all installation within a drop ceiling, or that it alters the definition of "exposed". It does validate that it is considered "accessible". It simply gives room for installation of lighting or other equipment in an allowance for the potential distance between the securing surface and the dropped ceiling.

 

[hbiss]

If a jbox is allowed to be "covered" "hidden" and considered "accessible" when covered by a dropped ceiling, the wiring above a dropped ceiling is also accessible therefore, for all extensive purposes "exposed". Look at article 100 definition of "Exposed": "On or attached to the surface or behind panels designed to allow access." Therefore 334.15(C) does apply.

There is a difference between "exposed" and "accessible". Exposed means unprotected and susceptible to tampering or damage. "Accessible" means that something has to be purposely removed to expose the item.

-Hal

 

[James L]

There are several key conditions to your referenced article. 1 only in relationship to "securing and supporting" of NM. 2 last point of securing by an "approved means" must be "not more than" 4.5 ft from last point of attachment to the equipment. 3 for allowance to make a connection of "luminaries or other peice of electrical equipment". 4 and probably the most important condition, only applicable to "in one, two, or multifamily dwellings".
I don't see your distinction to be evident from your reference to give a free for all installation within a drop ceiling, or that it alters the definition of "exposed". It does validate that it is considered "accessible". It simply gives room for installation of lighting or other equipment in an allowance for the potential distance between the securing surface and the dropped ceiling.

It seems to be, the way you are reading it, does somebody has to run MC cable within a grid ceiling cavity, only under the joists. But then as soon as it leaves the joist area and turns into a Luminaire whip, then it can NM cable.

I'm simply saying that by allowing the 4.5 ft of NM cable as a whip for a luminaire, that automatically sets aside that grid ceiling cavity as an area that is "not affected" by the restrictions on exposed NM wiring.

Otherwise, it would be ludicrous to allow the luminaire whip to be in Romex. Because after all, a Luminaire and a junction box are not the same thing. All you have to do is look at a can light to see that. There is a junction box that has all the NM connections, then a whip from the junction box to the luminaire, the actual can

 

[Fred B]

It seems to be, the way you are reading it, does somebody has to run MC cable within a grid ceiling cavity, only under the joists. But then as soon as it leaves the joist area and turns into a Luminaire whip, then it can NM cable.

I'm simply saying that by allowing the 4.5 ft of NM cable as a whip for a luminaire, that automatically sets aside that grid ceiling cavity as an area that is "not affected" by the restrictions on exposed NM wiring.

Otherwise, it would be ludicrous to allow the luminaire whip to be in Romex. Because after all, a Luminaire and a junction box are not the same thing. All you have to do is look at a can light to see that. There is a junction box that has all the NM connections, then a whip from the junction box to the luminaire, the actual can

Code seems to be very simple, 334.12 "Uses Not Permitted (A) Types NM, NMC, and NMS, Types NM, NMC, and NMS cables shall not be permitted as follows:
(2) Exposed within a dropped or suspended ceiling cavity in other than one- and two-family and multifamily dwellings."

This indicates that whereas NM type cables may be allowed in other types of structures per 334.10(3), it also states unless as prohibited in 334.12. (Part of it Quoted above). So even if NM can be used in a building that is other than residential, it can not be used within the drop ceiling in other than dwelling units, this is not just about a whip, it's all the cable within the dropped ceiling if structure is not a residential.
Residential meeting the idea of a 1-2 or multifamily dwelling can use the NM, but no other type of building. Thus planning would need to happen prior to installing NM in a "non-residential" structure to know if a dropped ceiling is being planned to be used to avoid violating 334.12(A)(2).

 

[James L]

Code seems to be very simple, 334.12 "Uses Not Permitted (A) Types NM, NMC, and NMS, Types NM, NMC, and NMS cables shall not be permitted as follows:
(2) Exposed within a dropped or suspended ceiling cavity in other than one- and two-family and multifamily dwellings."

This indicates that whereas NM type cables may be allowed in other types of structures per 334.10(3), it also states unless as prohibited in 334.12. (Part of it Quoted above). So even if NM can be used in a building that is other than residential, it can not be used within the drop ceiling in other than dwelling units, this is not just about a whip, it's all the cable within the dropped ceiling if structure is not a residential.
Residential meeting the idea of a 1-2 or multifamily dwelling can use the NM, but no other type of building. Thus planning would need to happen prior to installing NM in a "non-residential" structure to know if a dropped ceiling is being planned to be used to avoid violating 334.12(A)(2).

I thought we were talking about residential work exclusively. What's the point of talking about running boards to protect NM in a ceiling that doesn't allow NM at all?

 

[sgtsparky]

Oregon Has an exception for other than 1&2 family residences that it has to be installed to 334.15 this requires the running boards for perpendicular if the size is smaller than 2 #6 or 3#8 . this makes sense to me if NM is allowed why would a dropped ceiling change it.
or you would be in a world of hurt in a building that was built open then later a suspended ceiling added.

 

[jimport]

There would be no issue if the cables were run through bored holes or on running boards and the drop ceiling were added later. NM above a drop ceiling is not exposed or subject to objects being hung from it.

 

[infinity]

this makes sense to me if NM is allowed why would a dropped ceiling change it.

The reason that exposed smaller NM cables has to be run through bored holes or on running boards in a basement that is unfinished is because the NEC wants to prevent someone from hanging stuff from the cable if it's nailed to the underside of the joists. Once a ceiling is installed it's likely that no one is going to remove a tile just to hang up their laundry but if you go back to Fred's post #11 and look at the definitions it seems that even above a hung ceiling the wiring is still considered exposed.

 

[petersonra]

There is a difference between "exposed" and "accessible". Exposed means unprotected and susceptible to tampering or damage. "Accessible" means that something has to be purposely removed to expose the item.

-Hal

Exposed (as applied to wiring methods). On or attached to the
surface or behind panels designed to allow access.

 

[infinity]

Exposed (as applied to wiring methods). On or attached to the
surface or behind panels designed to allow access.

The fact that this definition is written in a way that includes the area above a hung ceiling is silly.

 

[petersonra]

The fact that this definition is written in a way that includes the area above a hung ceiling is silly.

The restrictions on the use of cord are by and large silly too, but they are there.

 

[sgtsparky]

I see the wiring method as permanent but drop ceiling like T bar as temporary, I have removed them in several homes so with that in mind I don’t think it’s silly.