Box Fill Calculator - Device Based

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E40

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Florida
Hello All,
I've got a product invention that will be installed into an electrical box but I'm having trouble determining the appropriate size box that it requires. Most of the calculators I've found online require inputs about number of conductors, then calculate minimum box size and appropriate device size. I'm in need of a calculator that starts with the device size to calculate the appropriate box and number of conductors.

Does anyone know of a calculator capable of this? Or is there an alternate approach that I've missed in my searches?

Thanks in advance for the assistance

Regards,
Eric
 
roger

roger

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Start at 314.16 and read through (A) and (B), it might give you some help.

Roger
 
Dennis Alwon

Dennis Alwon

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The nec assumes the worst case scenario for devices when figuring fill. I suppose they use the gfci as the basis for requiring 2 conductor count for the device. If your product isn't any larger than a gfci then there should not be an issue but the NEC does not actually state what size the device should be. I suppose this is something that may need to be tested by UL or some other 3rd party lab
 
Dennis Alwon

Dennis Alwon

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There is nothing in the NEC as I mentioned earlier. If the device has a yoke then we as installers must count the device as 2 conductors for our conductor fill. The number of conductors is based on the size of the wire as well as the cu. in of the box. Unless this device is extra large then a one gang box should work but I have seen some yoke devices that need a 2 gang box.
 
E

E40

Member
Location
Florida
Dennis Alwon said:
There is nothing in the NEC as I mentioned earlier. If the device has a yoke then we as installers must count the device as 2 conductors for our conductor fill. The number of conductors is based on the size of the wire as well as the cu. in of the box. Unless this device is extra large then a one gang box should work but I have seen some yoke devices that need a 2 gang box.
Click to expand...

Dennis,
Thanks for the feedback. I just read through a couple other forums and think I've found an answer to my question so I figure I'll double check here. Sounds like there isn't a literal volume requirement for the device itself, it just needs to be counted as 2 conductors. The calculator I had found showed 4 cu. in. for the device which confused me. But now my understanding is that they calculated 4 cu. in. by multiplying the 2 conductors by 2 cu. in. because I was using #14 wires.

If it sounds like I've misunderstood please let me know. Otherwise, thanks for the assistance!

Regards,
Eric
 
E

E40

Member
Location
Florida
Dennis Alwon said:
There is nothing in the NEC as I mentioned earlier. If the device has a yoke then we as installers must count the device as 2 conductors for our conductor fill. The number of conductors is based on the size of the wire as well as the cu. in of the box. Unless this device is extra large then a one gang box should work but I have seen some yoke devices that need a 2 gang box.
Click to expand...


Actually your comment makes we curious about one last thing...if it has a yoke it counts as two conductors. Is that regardless of whether there is 1, 2, 3, or more receptacles on the yoke? For example...the Legrand Adorne has 3 outlets in the design but only one yoke/strap. Would it still count as 2 conductors?

Thanks again
 
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GoldDigger

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E40 said:
Actually your comment makes we curious about one last thing...if it has a yoke it counts as two conductors. Is that regardless of whether there is 1, 2, 3, or more receptacles on the yoke? For example...the Legrand Adorne has 3 outlets in the design but only one yoke/strap. Would it still count as 2 conductors?

Thanks again
Click to expand...
Yes.
The wires actually connected to it are counted individually but the fudge factor for the device (yoke mounted) itself does not depend on its complexity.
 
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