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Reno Are you sure the EMT you are seeing in simply not the EMT run by the Ansul contrator for the trip cable they run?
Bob Badger
Construction & Maintenance Electrician
Massachusetts
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As I stated, Bob ... I was not justifying the practice; I was reporting it. I went on to ask for the history of the requirement ... with a code that is revised every three years, it is not impossible that the hoods I've seen pre-date any such requirement.
(BTW... I'm going to post a few pics here in a few ... and see if I can take some better ones. I think they'll help our discussion.)
Last edited by renosteinke; 05/23/07 03:59 PM.
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This thread has become a good discussion about range hoods. I thought I'd add a few pics to help out.... The first two are of a residential install. The hood was fabricated by the customer, who happened to be a HVAC / Plumbing / Mechanical contractor. ![[Linked Image]](https://www.electrical-contractor.net/forum/RS/550_Hood_(outside).JPG) Now, it turns out that hoods set over an island like that need to be designed differently than hoods place along a wall, and require double the airflow. I do not believe this guy took that into account. More interesting is his design for the lighting: ![[Linked Image]](https://www.electrical-contractor.net/forum/RS/550_Hood_(inside).JPG) I think we can see where this is a poor design - even for a residential hood! The next pic is from an 18 month old restaurant. While the internal EMT is not visible, you can see one of the lights: ![[Linked Image]](https://www.electrical-contractor.net/forum/RS/550_Stove_overview.JPG) I include this because the NEC Handbook, in it's commentary that 'conventional enclosed and gasketed fixtures are not permitted," saying that all fixtures, even flush mounted ones, need to be specifically listed and marked for the purpose. Yet, again, ordinary vaportight fixtures, as seen in this pic, seem to be the norm. Indeed, replacement globes for these are readily available at restaurant supply houses; I'd be very surprised if those globes were ever even in the same Zip Code as UL. I'll try to get better pics, and I encourage others to add theirs.
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Had a simular situation a while back, and my take on it was the code applied to commercial premises only, for the following reasons: 1.)Effluent output of residential would be significantly less. 2.)Just about any listed residential hood does not follow the requirement laid out in this code. Many have exposed wiring inside, and open lamps. However, I did try to use this as a guideline for the install. While not having to adhear to the letter, kept wiring out of the path of effluent and used sealed fixtures. (For my own benifit and piece of mind.) (2002)410.4(C) In Ducts or Hoods. Luminaires (fixtures) shall be permitted to be installed in commercial cooking hoods where all of the following conditions are met:
(1) The luminaire (fixture) shall be identified for use within commercial cooking hoods and installed so that the temperature limits of the materials used are not exceeded.
(2) The luminaire (fixture) shall be constructed so that all exhaust vapors, grease, oil, or cooking vapors are excluded from the lamp and wiring compartment. Diffusers shall be resistant to thermal shock.
(3) Parts of the luminaire (fixture) exposed within the hood shall be corrosion resistant or protected against corrosion, and the surface shall be smooth so as not to collect deposits and to facilitate cleaning.
(4) Wiring methods and materials supplying the luminaire(s) [fixture(s)] shall not be exposed within the cooking hood.
FPN:See 110.11 for conductors and equipment exposed to deteriorating agents.
Commentary: The requirement in 410.4(C)(4) was initially taken from NFPA 96, Standard for Ventilation Control and Fire Protection of Commercial Cooking Operations. NFPA 96 provides the minimum fire safety requirements (preventive and operative) related to the design, installation, operation, inspection, and maintenance of all public and private cooking operations, except single-family residential dwellings. This coverage includes, but is not limited to, all cooking equipment, exhaust hoods, grease removal devices, exhaust ductwork, exhaust fans, dampers, fire-extinguishing equipment, and all other auxiliary or ancillary components or systems that are involved in the capture, containment, and control of grease-laden cooking effluent.
Also, NFPA 96 is intended to include residential cooking equipment where used for purposes other than residential family use, such as employee kitchens or break areas and church and meeting hall kitchens, regardless of frequency of use.
Grease may cause the deterioration of conductor insulation, resulting in short circuits or ground faults in wiring, hence the requirement prohibiting wiring methods and materials (raceways, cables, lampholders) within ducts or hoods. Conventional enclosed and gasketed-type luminaires located in the path of travel of exhaust products are not permitted because a fire could result from the high temperatures on grease-coated glass bowls or globes enclosing the lamps. Recessed or surface gasketed-type luminaires intended for location within hoods must be identified as suitable for the specific purpose and should be installed with the required clearances maintained. Note that wiring systems, including rigid metal conduit, are not permitted to be run exposed within the cooking hood.
For further information, refer to UL 710, Safety Standard for Exhaust Hoods for Commercial Cooking Equipment.
Mark Heller
"Well - I oughta....." -Jackie Gleason
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If the hood is truly listed as a 'commecial hood' it is likley a violation to be installed in a dwelling unit.
Just as you can not install a commercial range in a dwelling unit.
Last edited by iwire; 05/25/07 02:31 AM.
Bob Badger
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Massachusetts
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no make-up air?
....at least the doors in the house won't have a problem staying closed :[
Tom
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Reno:
I see that Mike and Bob said my 'piece' above. NO wiring allowed on the 'inside'.
The tapered base luminaires are a requirement of NSF (Health) as far as I can tell.
John
John
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I've been running around, taking pics .... and, surprise, some of my customers actually seem to have legal hoods.
The ones with the EMT inside just might be retrofits. I have found several hoods without any lights at all.
Pics in a few days, I promise!
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no make-up air?
....at least the doors in the house won't have a problem staying closed :[ If it was a commercial building that would be the case, in a dwelling unit it will be hard to shut the door(s).
Bob Badger
Construction & Maintenance Electrician
Massachusetts
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Tom
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