Installing a New JB for Range Hood

13 years ago

Hi folks. I ripped out my old range hood (original 1960's vintage, non-venting, VERY nasty). I am replacing it with a new ducted/non-ducted hood.

The power comes from an old 2 conductor cable with a copper ground wire, that just sticks out of a hole in the wall, located above the backsplash over the cooktop. The old power cable was terminated directly to a block inside the old range hood. I just cut the old range hood away at the the power cable. So now I have the exposed cable (capped with wire nuts) sticking out of a hole in the wall.

So, to do this right, I want to install an actual junction box to hold any extra cable and the wiring from the range hood. I plan to use wirenuts to connect the power to the leads on the range hood.

I've started trying to open up the wall around the hole where the cable sticks out. It was a real job because my house is all gypsum board with a plaster veneer or plaster on lath. Finally, I've got about a 3x4 rectangle cut out. The cable is stapled to a stud behind the wall. My plan is to remove the staples and mount a jb to the same stud and pull the old cable through it.

My question is, what is the appropriate type and material to select for my junction box? Are there any special criteria that come into play when selecting the right jb for this application? Steel or plastic?

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Comments (6)

petey_racer
13 years ago
You do NOT need, or want, a junction box behind a range hood. It gets wired directly into the back of the hood, just like the old one.
That is the right way to do it.
tekbro
Original Author
13 years ago
OK. I'll just patch that bad boy back up then!

So why is that such a bad idea? Code compliance? Safety? Fire Hazard? All of the above?

Not that I'm arguing with you, I'm just curious. The issue with my particular install is having sufficient slack in the line to the range hood. And the line is the original wiring from the 1960's, and the sheath is not in very good shape. I don't think the line is completely dedicated to the range hood alone, either. It it time to run a whole new line to a new, dedicated breaker?
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Concerning more ventilation: Most of the time it's fine. I don't mind cooking smells in the house. I've never cooked fish or something with strong unpleasant odors. The only times I really want more is when I'm sauteeing onions or searing steaks and I get smoke going. I turn it on in those cases but it doesn't even have enough pull to really pull the smoke up to the vent if that makes sense. Also I have greasy build-up on top of my cabinets. I had no idea that a fan was even suppose to be used for greasy things (can you tell my mom never used hers either), so now that I know a fan could help with that it would be nice if I had one that worked better so I didn't have to scrub the top of my cabinets every year. As far as current venting goes; if I had any it would have to be in the existing wall, nothing goes through the cabinet over the stove. Also there is nothing on the roof or side of the house that indicts anything being vented anywhere in this area of the house. Weedmeister, after reading your message I realize I was incorrect in my thinking of where the duct connects to the hood. I was thinking they would connect to the back side of the hood (where it touches the wall) but after reading this I think you are saying the duct will connect above the hood. Is that correct? In that case I'd have 2 turns in either direction (one from the fan to the wall and one from the wall to go up or to the side. I'd definitely want the vent in the wall because I have a huge open space above the cabinets up to the cathedral ceiling and I wouldn't want to see a vent running there. Thanks for helping me clarify this stuff. More and more it sounds like going ductless might still be my best choice. The filters on them were rather expensive and I was starting to think maybe over the long term that just installing the ducting work would be cheaper than replacing all those filters. So if I'm going to install a ductless hood, does the CFM's matter so much. I was considering the Broan Evolutions QP130 or Broan QP230 hoods.
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Here is another link which assumes too little for a kitchen hood https://dsps.wi.gov/Documents/Programs/UDC/WorksheetOptionalMakeupCombustionAir.pdf Commentary on Minnesota's code https://structuretech1.com/how-to-determine-if-makeup-air-is-required/ A comment from Broan's web site: *The International Residential Code Section M1503.4 and the International Mechanical Code Section 505.2 require Make-Up air for all domestic range hoods in excess of 400 cfm. States such as California, Wisconsin, and Minnesota have different requirements, as does ASHRAE 62.2. Always check with your jurisdiction for specific Make-Up air requirements and code amendments that are applicable in your area. The above statement is on this template page, which may be used to find WI's requirements vis-a-vis Broan's MUA hardware. http://tools.broan.com/muatemplate.aspx The rest is left as an exercise for the student. :)
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Billl
13 years ago
Unless you have a monster, industrial range hood or hood/microwave combo, it doesn't need its own circuit. If the wire is nicked or the insulation is damaged, then yes, it is time to run a new wire.

As for why you don't put it in a junction box: You aren't allowed to "bury" junction boxes behind walls or any permanently items. You have to be able to access them in case there is a problem.

Also, as a practical measure, junctions are a possible failure point. A continuous piece of wire is just much more reliable.
tekbro
Original Author
13 years ago
Both Billl and petey racer make loads of sense. Pain in the butt though it is, I think replacing that lead is the right thing to do. The existing isn't nicked, necessarily. But it is visible aged, and the outer insulation feels more like brittle, dry rotted fabric than the slick, pliable insulation you find on modern NM. The fun part will be tracing this thing out.
tekbro
Original Author
12 years ago
OK. So replacing the existing line turned out not to be as straight-forward as I thought. After tooling around my attic several times, trying to trace this line, I have been unsuccessful. I am fairly certain that it goes all the way back to the breaker panel.

I don't think there's enough lead left to make up the connection to the hood. If I don't use a junction box to make the new connection, is it permissible to make some sort of butt splice behind the wall and tape it up? Or is this an even worse idea than hiding the box behind the hood?
brickeyee
12 years ago
"If I don't use a junction box to make the new connection, is it permissible to make some sort of butt splice behind the wall and tape it up? Or is this an even worse idea than hiding the box behind the hood? "

All connections must be in accvesable junction boxes.

If the cable is in the attic you could cut it back to there (the insulation is liable to be in better shape) and then use a section of NM from the attic junction box down to the hood.

ALL boxes must remain accessible, and while it is possible to remove a vent hoed for access , it is going to be a real PITA (unlike pulling out a DW or range).

Installing a New JB for Range Hood

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Installing a New JB for Range Hood

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