inspectorjoe

[inspectorjoe]

please enlighten me in regards to this metal pancake box, listed as suitable for fan mounted assembly. its states that it has a 6.0 cu. in. capacity. most people are using this with 14/3 how does this comply with 314.16. second issue is where does it explain in the NEC that a furring strip (strapping) is not considered suitable to use to mount boxes in ceiling to house luminaires. this to me is not part of the structure or member of the building. code reference please.

 

[Ponchik]

please enlighten me in regards to this metal pancake box, listed as suitable for fan mounted assembly. its states that it has a 6.0 cu. in. capacity. most people are using this with 14/3 how does this comply with 314.16.

second issue is where does it explain in the NEC that a furring strip (strapping) is not considered suitable to use to mount boxes in ceiling to house luminaires. this to me is not part of the structure or member of the building. code reference please.

14-3 cable does not comply with box fill calculations. Most inspectors do not catch this violation. IMHO, it is a minor point, not a real hazard.

 

[iwire]

please enlighten me in regards to this metal pancake box, listed as suitable for fan mounted assembly. its states that it has a 6.0 cu. in. capacity. most people are using this with 14/3 how does this comply with 314.16.

The only way around that I can think of is using a canopy with a marked volume.

where does it explain in the NEC that a furring strip (strapping) is not considered suitable to use to mount boxes in ceiling to house luminaires.

I disagree and I think you will find you are alone in that belief.

It is suitable to support the ceiling, it is certainty suitable to support the fixtures.

 

[inspectorjoe]

strapping

strapping

if the boxes are nailed to strapping with a thickness of 3/4" this tends to split the wood leaving the box to becoming loose over time due to vibration within the house or condo. if it is sandwiched (two pieces of strapping screwed together) the nails for the box fall directly between the slot of the two pieces of strapping, making the electrician mount the box on an angle so one nail penetrates the upper strapping and the other falls between. how is this compliant. is this a judgement call or is the legitimate?

 

[Dennis Alwon]

if the boxes are nailed to strapping with a thickness of 3/4" this tends to split the wood leaving the box to becoming loose over time due to vibration within the house or condo. if it is sandwiched (two pieces of strapping screwed together) the nails for the box fall directly between the slot of the two pieces of strapping, making the electrician mount the box on an angle so one nail penetrates the upper strapping and the other falls between. how is this compliant. is this a judgement call or is the legitimate?

IMO, it is an authority having jurisdiction call. I tend to agree that the slats can be very precarious especially if there was a heavy fixture involve. I doubt you will find any reference in the nec other than what is stated in

314.23 Supports. Enclosures within the scope of this article
shall be supported in accordance with one or more of
the provisions in 314.23(A) through (H).
(A) Surface Mounting. An enclosure mounted on a building
or other surface shall be rigidly and securely fastened in
place. If the surface does not provide rigid and secure support,
additional support in accordance with other provisions
of this section shall be provided.

IMO this makes it an authority having jurisdiction call

 

[al hildenbrand]

if the boxes are nailed to strapping with a thickness of 3/4" this tends to split the wood leaving the box to becoming loose over time due to vibration within the house or condo. if it is sandwiched (two pieces of strapping screwed together) the nails for the box fall directly between the slot of the two pieces of strapping, making the electrician mount the box on an angle so one nail penetrates the upper strapping and the other falls between. how is this compliant. is this a judgement call or is the legitimate?

If a specific box installation you are inspecting actually has fastener-split wood, or nails in the gap between slats, then you have the Code citation that Dennis references to back you.

The choice of fastener (screw, nail, etc.) and exactly how it is installed to secure the box, together, are what the Code pays attention to in 314.23.

The 3/4" firring strip, itself, is not the sole issue. The attachment of the box is the real focus, and one workman's execution of the attachment will differ from another with the same identical materials and situation.

 

[mwm1752]

I don't think I've seen a 3" size listed fan box they usually are 4" but you apparently have seen them.
As for the box supports grab that sucker & see if it is not rigidly supported -- a loose box should be able to be pulled off by hand. I'd keep in mind a device weighs little and generally has no force placed upon it. Fixture can be supported with 6# screws if less that 6 lbs (not much sheer force). Code can back you in your determination but a reasonable conclusion seems to a proper approach in the field when working with trademen. BTW they make several types & different supports for boxes for this installation.