I've been asked to install a commercial range hood in a fancy residential kitchen. The hood is in good used condition with luminaires identified for the application. It is wired so that the junction box is on the outside of the hood with EMT conduit penetrating the side and routed through the hood's ceiling to each fixture. Hi-temp conductors throughout etc. Referencing NEC 99 & 02 (my 05 code is in my shop, regardless, here in NYS we are still working under the 99 code) 410.4(C)(4) ..."wiring methods and materials supplying the luminare(s) fixtures shall not be exposed within the cooking hood" what would be your definiation to "exposed"? Also, does this code apply to a commercial hood installed in a single-family residential kitchen?

I'd rather not route the conduit on the exterior of the hood as it will be plainly visible.

Need some good argument here for the AHD.

From what you said....the wiring from fixture to fixture to source/switch CANNOT be surface mounted under/in the hood area. The fixtures are wired from 'topside' and all the wiring is 'topside'.

As to a comm hood in a resi...IMHO, I see nothing to object to. What are you using for exhaust fan? and MUA??

John

I don't think I've ever seen a hood that did not have EMT run inside it. There are a few reasons, best as I can see:
- Hood penetrations are kept to a minimum, for cleaning purposes. Where the pipe does go through the hood, special fittings - NOT available to electricians - are used that seal all around the conduit. This is, as I understand it, a requirement of the hood fire code, as well as a means to keep cleaning materials within the hood; and,

- Many hoods - again, for fire reasons - are made with a double wall. Making penetrations, and sealing them, is problematic at best.

The presence of the pipe within the hood does not seem to be any obstacle to the cleaning operations. Nor does the pipe seem to be damaged in the least by the chemicals.

I'd be interested in learning the history of that code wording.

Now, as far as I know, that same section of the NEC is worded such that it only applies to commercial installs. Not that it's a bad idea ... I once encountered a custom-made hood in a house that was not in compliance, and I quite merrily cited this part of the code to make the contractor get rid of the exposed romex and keyless fixtures! (I even posted pics at ECN).

Reno:
Are you saying EMT from light to light and/or feeding in??
Also, have you noticed the 'new' tapered luminaire bases?

John

I mean EMT from light to light ,,,, and even extending down the side, to serve an receptacle.

Oddly enough, even in heavily used commercial hoods, I have not encountered heat-damaged conductors.

No, I have not noticed the 'new bases.' But then, even my 'new' restaurants have obtained their hoods through, well, creative channels.

Hood and fan was existing to be re-installed. The exhaust is ducted thru the wall and it's wiring is not "exposed". Both switches are typically mounted outside the unit and the switched legs are concealed within wall, etc. The lighting leg exits wall outside of the hood and is discretely routed to where it enters a junction box outside of the hood. No make up air, no fire supression system, fire-rated back wall, shunt-trips, etc. It's residental. Right?

The inspector saw the hood sitting outside when he did the service inspection and quoted this code to me. I think I'll just let him check out the finished product for himself and give the HO the bad news. Maybe they'll even make us sprinkler and supervise the place when they find out what a big party they throw every christmas.

I agree ... no need for 'Ansul" system on residential hood.

In the handbook notes in my 2002 NEC it says that this is taken from NFPA 96 which includes all hoods except those installed in single family dwellings.
Notes say that "wiring systems, including RMC, are not permitted to be run exposed within the cooking hood."
I'd look up NFPA 96, discuss the notes in 99 NEC for this section if they are similar, and say that this is not a commercial location where the hood is installed. I'd also use EMT compression fittings that are water-tight. Some are not...

Whatever reasons you can think of do not change the fact it is a violation to run the conduit inside the hood.

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?

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.)

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.



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:




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:




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.

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.)

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.

no make-up air?


....at least the doors in the house won't have a problem staying closed :[

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

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!

If it was a commercial building that would be the case, in a dwelling unit it will be hard to shut the door(s).

what's the difference?

what's the difference?

Type 1 commercial range hoods can take in grease.
Type 2 commercial range hoods cannot take in grease.
Both cover the entire top of the range, and are discharged directly to the exterior.
Residential range hoods aren't even required to be installed and do not usually cover the entire top of the range, and are not required to discharge outdoors (but they cannot discharge anywhere else except into your face).

As promised, I ran around town looking at some commercial range hoods, and took a few pics. Much to my astonishment, I encountered a few that actually appear to comply with the NEC!

This first one ... looks like I got there right after the cleaning guy ... has EMT to Appleton vapor-tights. In case you were wondering, the CFL's seem to work really well in this application:





Another restaurant also had EMT to the hood lights, with an extension to serve a stove-side receptacle:







Finally, her is a better view of the hood at that Chinese place:




Much to my surprise, the last hood looks to be in compliance. I was careful not to tell the owners that; I think they consider code compliance to be a mark of shame, and they would surely change it if they knew!

You can put a commercial range in a dwelling - it needs to be modified somewhat though. I believe you need to swap regulators and orifices. Or at least that is what they did before Wolf/SubZero made those pricey commercial look-a-like units. Then I think Wolf caught on and started making them that way. I have also seen one done that way recently that made it through all kinds of inspections to make sure it was converted. Only so much gas flow, etc.

Back on hoods.... You can custom build (as many commercial units are) any hood you like for a single family dwelling. With any appearance (commecial looking/rated if you like) or any acceptable CFM, and not have to follow the NEC for "Commercial Hoods" until the building is somehow re-zoned commercial. (By the way the NEC wrote it.) Otherwise it is just a "custom hood", and only need be listed if the AHJ wants it to be. Or at least that has been my experiance on it...

Did a bunch of reserch about this a few years back. (I wish I still had it, all I can find is the letter I wrote about it.) And from what I gathered that single family had relitively few restrictions... Multi-family had a few more in terms of listing requirements, and commecial had a rather wide range of requirement in all kinds of building codes.

Mark it is still a listing violtion to use commercial ranges in a dwelling unit.

The issue is not the gas flow but the fact that commercial ranges are not made to be installed into combustible construction. (Wood cabinets etc)

Perhaps some models have a duel listing but that is just a guess.

what I was wondering is why the doors in a house won't slam shut when these big hoods are turned on.
I always thought MUA was needed to prevent that from happening ...or you have air coming in thru every open window and leak

Because exterior home doors swing in and commercial doors swing out.

yes, thats right ..but there would still be a neg. pressure..
those hoods are more problems then they are worth...IMHO

Without a doubt and combine that with any fuel burning vented appliances (furnace, boilers, fireplaces) and you can have a real issue.

The typical old Florida house might whistle a bit but I doubt you would really generate any real vacuum. I have 2 big "whole house" fans that exhaust into the attic. Occasionally my kid would turn them on without opening any windows. You would think it would make your ears pop but it just demonstrated how leaky crank out "awning" windows really are. I can see it on my barometer tho. Sometimes the storm warning will go off from the rapid pressure drop.

Well I can't speak for your house but in the 'cold' areas people die every year from CO poisoning, sometimes it is from simple as having an exhaust fan on which drags the flue gases from the oil or gas fired furnaces and boilers back down the flue and into the home.

The fact that you can see it on you barometer kind of proves the point. Now if you had a oil fired boiler in the house with the typical natural draft venting you would have some issues.

The large majority of fuel burning appliances I see are not power vented they use natural drafting, it takes very little 'low pressure' to stop the natural draft.

This is probably not an issue you see in the land of Air conditioning, heat pumps and electric resistance heating but make no mistake it can be an issue in my area.

I have heard of this thing ;-)

Actually when I lived up in the frozen north I do remember concerns about houses being too tight and having flues not breathing properly. You are right, that is not a big deal around here since 99.9% of our appliances are electric. Florida did just add CO detectors to the building code for any home with gas, oil, generators or an attached garage.

Thank you, Food Network.

It used to be that a good cook could do the job on a standard residential range. It tasted good for sure.

Nowadays, unless they have a 600,000 BTU gas commercial range with a custom hood, their food doesn't come out so great after all.

Are people really such puppets on a string with the home improvement and cooking shows holding them? It's all a marketing gimmick; these TV networks are heavily-funded by Wolf, Garland, Viking, blah, blah, blah. Take a look at the credits at the end of their shows and you will see for yourself.

"Let's convince people that they will need to invest in a $5,000.00 commercial gas range.

-Oops, too much BTU output, so the customer will need a $2,000.00 hood to prevent asphyxiation in an energy-efficient residence.

-Oh, wait a minute. They don't have gas service but they still rush out and buy one. Now comes the West Virginia Christmas decoration holder: The above-ground propane tank. They pay more money to put 20 gallons into this tank than they do with gasoline in their SUV.

-Oh, wait a minute, electric ovens are better. Now, let's convince them to invest in a $6,000.00 residential version of this commercial range that includes an electric oven. Now we really have the customers dancing."

Rachael Rae, Emmiril, Barefoot Contessa, etc. say it's best, so this is what the customers will rush to buy.

Ever notice how they focus in on the "tick-tick-tick" ignitor sound of the burner when they show them melting butter or warming olive oil?

My wife is a great cook and gets it done using a standard smooth-top electric range. She's not cooking for a restaurant, just the family or an occasional gathering. All of that "instant heat" debate is a bunch of crap. I accidentally turned on the wrong burner for ten seconds. I brushed my hand across that one and I can assure you, it was VERY hot!

I do all the cooking around here and I haven't been hampered by my slick top electric. In fact I can do some tricks you don't see on TV. Fast way to brown a couple tortillas, Smooth out a piece of aluminum foil right on the hot burner surface, a few drops of oil and slam the tortillas down. Just keep them moving and get them off the cool side. I do that when I make Fajitas after blasting the other stuff.
I do have a few gas burners but they are outside in the "country kitchen".

I am coming to your house for tortillas!

Talking to a Plumber buddy, and appartently just about all ranges have various listings as to BTU from combustable, and just about all have a range and angle from the burner, Much the same way lumens are measured from angle from the fixture and distance from the fixture are for us. And swapping out the orifice and regulators is much in the way of swapping out lamps to change it. According to this guy the only thing that would have a hard time making muster is a commercial WOK, as the BTU is way too high either way. As the BTU high range (area) makes it all the way to most cielings. But relitively easy to do with most ranges (stoves)...

Also appparently it is the range that sets the distance from range to hood and min CFM of the hood. I knew that, but makes more sense relating it to the BTU of the range....

I have read the UL standards for commercial as well as residential ranges, and there is only one substantial difference between the two.

Residential ranges have a maximum temperature specified for the exposed front face, such as an oven door. Commercial ranges do not have that spec.

So, it is conceivable that a commercial range would have an oven door that might get hot enough to burn a child that might lean against it. We don't KNOW this ... it's just that UL has not bothered to take the measurements.

I agree, it is more a case of the unknown. In all likelihood the range would perform fine.

That aside as far as I am concerned I can not knowing connect a unit with a UL tag that says Commercial in a dwelling unit.

It would be a 110.3(B) violation plain and simple.

I'm not so sure that installing a 'commercial' appliance in a residential setting (or the opposite) is, in and of itself, a violation of 110.3(B).

While the appliances are 'intended' for use in the described setting, that setting is not defined. "Commercial" suggests "commerce," that is, the exchange of money ... yet it is quite reasonable for schools, hospitals, army bases, soup kitchens, etc., to have 'commercial style' kitchens.

What is important is that the specific installation requirements be complied with, and any changes be undertaken carefully.

For example, the evaluation of many commercial appliances assumes the presence of an NFPA 96 compliant commercial range hood.
Another assumption, in many cases, seems to be that commercial appliances will be 'hard wired;' residential ones are assumed to have a cord & plug.

Whether commercial or residential, the listing ought to indicate if the appliance is intended to be 'built in' or flush mounted.

Now, the "commercial" vs. "residential" distinction seems more important in non-electrical matters. For example, 'commercial' appliances generally need NSF certification - a standard that relates more to health department concerns than anything else. "Residential" appliances have no such expectation.

I see no specific code rule that says you CANNOT place a commercial appliance in a residential setting. To simply infer such is unfounded - but it is a clue that 'usual' practices may not be adequate.

I DO caution that 'commercial' may not be any better / tougher / stronger / etc. than a 'residential' item. While in many areas there is a hierarchy of residential > commercial > industrial, that is not always the case. They are different uses, with different needs, and using one in the 'wrong' setting often has disappointing results. In other instances, the only differences are in the Federal labeling requirements.

I only dwell on this because there is a fairly large group of folks out there who actively seek "commercial" appliances in the belief that they are better than "consumer" appliances. Sometimes this is correct- at a price. In other cases, it's pure vanity. To make matters worse, there often is absolutely no "listing" difference in the different appliances.

If there is a specific hazard, then by all means point it out to the customer. At some point, however, the consumer has to take responsibility for his choices. I'm not his nanny.

In my opinion it is one of the most basic violations of 110.3(B)

I also know many inspectors feel the same.



Yes that is absolutely true, and I know for a fact that some of these people where very disappointed when they found out the expensive commercial unit would not pass inspection of either the electrical or gas.

That is why manufacturers have stepped up and now sell units that 'look' commercial but are listed for residential use.

I am at a total loss why anyone would think a unit with a UL label that says 'Commercial' would be OK for Residential.

To me that would be the same as saying a unit labeled "indoor use" is just a suggestion.