Originally Posted By: five.five
This post was automatically imported from our archived forum.
which book should be referenced if someone would like to find out what size rafter would be acceptable for hanging a light fixture:
NEC
IRC
or other ?
which book should be referenced if someone would like to find out what size rafter would be acceptable for hanging a light fixture:
NEC
IRC
or other ?
Originally Posted By: jonofrey
This post was automatically imported from our archived forum.
Not sure why you are speaking of a rafter in this situation. Normally, fixtures are supported by the electrical box, which should be listed for the application. When considering the weight of fixtures and/or paddle fans I usually consider the basic rule of thumb for paddle fans. Listed boxes okay for fans up to 35 pounds. Independant support required if over 35 pounds.
This is referenced in the NEC.
Rafter spans and loads are referenced in the IRC.
--
Inspection Nirvana!
We're NACHI. Get over it.
Originally Posted By: jpope
This post was automatically imported from our archived forum.
Manufacturers recommendations will generally give you the specifications for hardware needed to hang fixtures.
Framing specifications are not usually based on proposed fixtures although there are some exceptions.
So my answer is "neither."
--
Jeff Pope
JPI Home Inspection Service
"At JPI, we'll help you look better"
(661) 212-0738
Originally Posted By: five.five
This post was automatically imported from our archived forum.
My first thought would be NEC because of the electrical portion of the question.
Then, second guessing myself, thinking it should be IRC, thinking about the 35 lbs. max for paddle fans, and electrical boxes required for fixtures.
The question did not mention electrical boxes for hanging fixtures, just the joist size (not rafter as previuosly stated in my first post) and electrical fixture, and what refence book would be correct.
Originally Posted By: jpope
This post was automatically imported from our archived forum.
| five.five wrote: |
| which book should be referenced if someone would like to find out what size rafter would be acceptable for hanging a light fixture? |
| five.five wrote: |
| The question did not mention electrical boxes for hanging fixtures, just the joist size (not rafter as previuosly stated in my first post) and electrical fixture |
Do you simply want to know how much weight a joist or rafter will support and where to find that reference? That would be an engineering question with several variables.
--
Jeff Pope
JPI Home Inspection Service
"At JPI, we'll help you look better"
(661) 212-0738
Originally Posted By: dhadler
This post was automatically imported from our archived forum.
Holy crap Batman! are you hanging an elephant or a fixture of some kind
Sorry, I just couldn’t resist.–
Darrell Hadler
Five Star Home Inspections
Medicine Hat, Alberta CANADA
Originally Posted By: ccoombs
This post was automatically imported from our archived forum.
I would say the question is both electrical and structural. If it is a “typical” fixture, then I would defer to John’s answer. If it is a heavier fixture that is raising structural concerns, then an engineer would be required. The codes (UBC and NDS) have span tables, but if I remember correctly, they don’t address point loads (I don’t use them, so I’m not sure if this is accurate). You can also find web sites with beam calculators if you want to get an idea for yourself.
Originally Posted By: five.five
This post was automatically imported from our archived forum.
for the book one would reference to find the answer to the question.
The test question was vague, too vague, and I wish I could remember the wording.
The abbreviated version of the question, was something like :
Which reference material would you refer to to find the size ceiling joist to install, hang, fasten, procure, attach, (pick one) a light fixture ?
If the question referenced how big of a hole to bore in a ceiling joist to allow for the fixture to be wired, I would say IRC, and not NEC.
Originally Posted By: roconnor
This post was automatically imported from our archived forum.
give you joist sizes for particular fixture weights (that is an engineered design for heavy fixtures).
Both the IRC (E3904.5) and the NEC (314.27.B) require independent support, other than typical outlet boxes attached to joists, for fixtures that weigh more than 50 pounds (close John ...;-P)
But if forced to choose a "best" answer, I would pick the IRC which gives the prescriptive ceiling joist sizes for joists that can support fixtures that weigh up to 50 pounds, and requires a special design for heavier fixtures ... 
--
Robert O'Connor, PE
Eagle Engineering ?
Eagle Eye Inspections ?
NACHI Education Committee
I am absolutely amazed sometimes by how much thought goes into doing things wrong