support of knob and tube lighting fixtures with new box

[tortuga]

I am replacing some knob and tube wiring in a historic craftsman home.
The existing fixtures (luminaires) are brass antiques and to be reinstalled.
There were no existing boxes so 3/0 boxes are being cut in to the lathe and plaster.
The old fixtures have 5" and 6" screw spacing that does accommodate a modern support strap.
The fixtures do have nice brass screws that used to attach directly to a 7/8" thick plank installed behind the lath and plaster above every fixture.

Upon reviewing 314.27 (2) and 410.30 ~ 410.36 I am not seeing a requirement that a luminaire be attached to a box.

Am I missing something somewhere?

Thanks

 

[PEDRO ESCOVILLA]

314.27 says (paraphrased, quoted) " and shall be required to support a luminaire weighing a mimimum of 50 lbs. then, further down in the paragraph, last sentence, it says "At every outlet used exclusivley for lighting, the box shall be designed or installed so that a luminaire may be attached. " now, lets go back to 300.15, where it says " a box shall be installed at each outlet or switch point for concealed knob and tube wiring." then, look at the definition of outlet, a point on awiring system at which current is taken to supply utilization equipment, then look at utlization equipment, ........ yes a box is required, you may have to get creative with your fixture strap, but you can do it ! shall, shall not or may, 3 distinct choices, lots of shalls on this one. also, you can't have splices in awiring system that aren't in a box, so again, yes a box is required

 

[jaylectricity]

Sounds to me like the box should be able to accommodate a fixture but your fixture doesn't necessarily need to be supported by the box, other than bonding the two together.

 

[K_Buz]

Doesn't any new fixture box need to be rated for fan support (assuming a fan could legally be put in that location)?

Is there being an inspection?

Is it a problem that those fixtures (probably) aren't listed? I know you wouldn't be able to put up a new, unlisted fixture, but at what point will it be allowed?

 

[kwired]

Sounds to me like the box should be able to accommodate a fixture but your fixture doesn't necessarily need to be supported by the box, other than bonding the two together.

exactly

Doesn't any new fixture box need to be rated for fan support (assuming a fan could legally be put in that location)?

Is there being an inspection?

Is it a problem that those fixtures (probably) aren't listed? I know you wouldn't be able to put up a new, unlisted fixture, but at what point will it be allowed?

Luminaires not being listed is a problem. See 410.6.



Read 314.27 specifically parts (A)(2) and (C) in 2011 NEC.

 

[Dennis Alwon]

I rarely hang a paddle fan from a box. I independently support it to the 2X4 I placed above the ceiling.

 

[K_Buz]

It is actually a state code (WI).

SPS 316.314 (2)
Outlet Boxes This is a department rule in addition to the requirements of NEC 314.27 (A): In a dwelling unit, a ceiling outlet box installed for use as a lighting fixture outlet in a habitable room or kitchen and located where a ceiling fan could be installed shall be a type listed for ceiling fan support.

(in case you were curious)

 

[kwired]

I rarely hang a paddle fan from a box. I independently support it to the 2X4 I placed above the ceiling.

I used to do that a lot and because of that I never used fan support rated boxes. That changes with 2011 NEC.

(C) Boxes at Ceiling-Suspended (Paddle) Fan Outlets. Outlet boxes or outlet box systems used as the sole support of a ceiling-suspended (paddle) fan shall be listed, shall be marked by their manufacturer as suitable for this purpose, and shall not support ceiling-suspended (paddle) fans that weigh more than 32 kg (70 lb). For outlet boxes or outlet box systems designed to support ceiling-suspended (paddle) fans that weigh more than 16 kg (35 lb), the required marking shall include the maximum weight to be supported. See related UL

Where spare, separately switched, ungrounded conductors are provided to a ceiling mounted outlet box, in a location acceptable for a ceiling-suspended (paddle) fan in single or multi-family dwellings, the outlet box or outlet box system shall be listed for sole support of a ceiling-suspended (paddle) fan.

Outlet boxes specifically listed to adequately support ceiling-mounted paddle fans are available, as are several alternative and retrofit methods that can provide suitable support for a paddle fan. Exhibit 314.9 illustrates two methods to support a fan from an outlet box that is listed for fan support. For a detailed view of an outlet box for a fan where the box does not serve as the sole support, see Exhibit 422.2. This section was revised for the 2011 Code. In new residential construction, it has become common to provide a wall-mounted switch with wiring for paddle fans to ceiling-mounted outlet boxes, even where paddle fans are not provided. This allows a paddle fan to be installed sometime in the future. This section now requires such installations to have an outlet box or outlet box system that is listed for the sole support of a fan.

You now must put in a fan rated box if provisions are made such as an extra conductor for powering the fan even if you do not intend to install a fan. I guess you can still choose to support the fan independent of the box if you wish - but the box is already rated for supporting it - unless it is a really heavy fan then maybe not.