ECN Forum
Posted By: WESTUPLACE Microwave - 08/27/08 10:29 PM
Looking at a job, question came up. They have a built in microwave. (not a vent hood type) The receptacle for the microwave is located in the cabinet directly above the microwave with a hole in the bottom of this cabinet to which the cord to the microwave passes thru. I think this is a code violation (although I see it alot)Am I correct?
Posted By: HotLine1 Re: Microwave - 08/28/08 12:06 AM
Standard install along with a single receptacle. Same basic set-up for a cord & plug connected dishwasher.
Posted By: renosteinke Re: Microwave - 08/28/08 12:24 AM
It's a good point ...and I just did such an install today!

That's exactly what the instructions specified; and the way the cord exited the microwave, I defy anyone to do it otherwise.

Yet, that does seem to conflict with the NEC rule against passing cords through walls or partitions. Perhaps - and I'm just guessing here - it's allowed here simply because the receptacle is still readily accessible. Such is not the case where the receptacle is in another room.

As such, though, I'd insist the hole be large enough for the plug to pass through.
Posted By: KJay Re: Microwave - 08/28/08 12:28 AM
IMOP, No violation there.
400.8 says flexible cords are not permitted be run through walls, structural ceilings, suspended ceilings, dropped ceilings or floors. Cabinets themselves have tops, bottoms, sides, faces, etc… but generally don’t qualify as walls, floors or ceilings.
Posted By: HotLine1 Re: Microwave - 08/28/08 02:20 PM
Reno:
The debate here at the NJEIA meeting was that a 'cabinet' shelf/wall/divider is not a 'partition', but a single, solid membrane. Now, run the cord thru a 'wall', that's a no-no.
Posted By: renosteinke Re: Microwave - 08/28/08 04:01 PM
Hotline, KJay ... I am inclined to agree. Indeed, for dishwashers, I much prefer an accessible plug under the sink, to either hard-wire, or a receptacle buried behind the unit. The challenge comes with the next step ....

IF such an assembly were submitted for listing, it would be expected that the opening be large enough for the plug to pass through, and that there be no sharp edges to damage the cord.
While that might be 'common sense,' I don't see anything in the NEC to require such measures. Conceivably, one would be allowed to make but a notch at the back of the cabinet to let the cord alone squeeze through, then mount the cabinet permanently to the wall.

Yesterday's microwave was such a case; for some reason, the installer started with but a slot, then changed his mind, and made a hole. Why? I have no idea.
Posted By: HotLine1 Re: Microwave - 08/28/08 05:00 PM
Reno:
I neglected to mention that the 'hole' must allow the cord cap (plug) to pass thru. A slot/notch buys a red sticker from me, and the other AHJ's here. The 'cord' must be NEC compliant for the DW and GD's. Most, if not all micros have factory cords.

Yes, good old common sense is not in the NEC
Posted By: sparkyinak Re: Microwave - 08/28/08 08:01 PM
By passing it through the bottom exposes the cord to damage when someone stick dishes or pans in the cabinet thus it is a violation.
Posted By: HotLine1 Re: Microwave - 08/29/08 12:52 AM
SparkyinAK:
I see your point, but have not seen or heard of any problems. If the receptacle is behind the micro, there may be the possibility of cord/plug damage also? Right??
How about the 'fridge being pushed back to far...oops, the cord shorted out. I guess the recessed box & outlet (bubble cover competition) would solve the behind the fridge problem.

Posted By: sparkyinak Re: Microwave - 08/29/08 01:29 AM
My respone is to the OP. It was a "fixed" microwave and the recept was passed through the bottom of the cabinet above. Therefore the microwave is not blocking the cord thus anything could in theory can be placed in the the cabinet. Since the cord is unprotected, it is exposed to potential damage. It is not a matter if anyone seen or heard problem. An unprotected cord put in a place in an area of potential damage is not exceptable (NEC 400.8(7)). If the recept is behind a fixed microwave, someone has to go out of their way to damage the cord.

As for your refigerator comment, if both receptacle and refrigerator are properly installed there will be no damage to the cord.
Posted By: renosteinke Re: Microwave - 08/29/08 04:27 AM
The microwave I recently dealt with was designed with the cord coming out the middle of an unfinished top. This microwave was clearly intended to be hung under a cabinet, with the cord passing into the cabinet - something specifically called for in the instructions. Darn near impossible to do otherwise.

As for stored stuff tripping over the cord ... not only is that upper cabinet nearly useless due to height ... most of it is devoted to letting the stove exhaust fan ducting pass through. It's pretty much a useless cabinet - more of a decorative front to hide the ductwork!

I think that into the cabinet is as good as it will ever be.
Posted By: sparkyinak Re: Microwave - 08/29/08 04:43 AM
It comes down to case by case basis
Posted By: SteveFehr Re: Microwave - 08/29/08 10:47 AM
Originally Posted by sparkyinak
My respone is to the OP. It was a "fixed" microwave and the recept was passed through the bottom of the cabinet above. Therefore the microwave is not blocking the cord thus anything could in theory can be placed in the the cabinet. Since the cord is unprotected, it is exposed to potential damage. It is not a matter if anyone seen or heard problem. An unprotected cord put in a place in an area of potential damage is not exceptable (NEC 400.8(7)). If the recept is behind a fixed microwave, someone has to go out of their way to damage the cord.

As for your refigerator comment, if both receptacle and refrigerator are properly installed there will be no damage to the cord.
Wait, since when is a cord and plug to an outlet considered "unprotected"? Last I checked, your argument applies to every receptacle in a house- you're not putting covers and conduit over the others, why worry specifically about this one?

The microwaves are UL listed, the cord exits the top, and the instructions specifically say to drill a hole through the cabinet. This is cut and dry, it's acceptable. To do it any other way would be illegal.
Posted By: sparkyinak Re: Microwave - 08/29/08 02:44 PM
Originally Posted by SteveFehr
Wait, since when is a cord and plug to an outlet considered "unprotected"? Last I checked, your argument applies to every receptacle in a house...

You are correct. Although in a sense these cords are not governed by the NEC, uou would not obviously place a cord where it would likely get damaged would you? Granted furniture do get jammed against plugs. This is really not our problem as sparkies. That is an end user issue. In the case of the microwave is a little different and only IF you are installing the receptacle and only to a certain degree. It is being installed for a specific purpose. As a sparkie, it should reasonbly be installed in a manner to minimize damage to cord in other words, high as practacle in the cabin. We can only do what we can do to minimize damage caused by the end user. People just do not think about stuff like that when putting dishes away.
Posted By: HotLine1 Re: Microwave - 08/29/08 04:07 PM
SparkyAK:
Not to totally disagree with you, as I said, I see your point.

To the best of my knowledge, the cord thru the cabinet is a 'normal' install as I stated originally. It is accepted by AHJ's, and I have not heard of anyone debating the install.

That said, I will broach this subject at the next (September) NJEIA meeting.

A little more logic...micro comes with a cord/plug from mfg. EC installs recept behind/inside dedicated micro cabinet space; micro does not fit because of recept/cap. So the micro (single recept) is installed in the cabinet above the micro space, and a hole of appropriate diameter is drilled in the upper cabinet bottom.

Cabinet depth and the depth of appliances should be considered IF it is mandated that the recept be in the dedicated space for the appliance. Alas this is a design issue, and the NEC is NOT a design tool. Also, common sense and good judgement are not within the NEC
Posted By: sparkyinak Re: Microwave - 08/30/08 12:22 AM
agreed smile
Posted By: schenimann Re: Microwave - 08/30/08 02:06 AM
Another violation I see with these recepticles is when they are cut into the cabinet, the ears rest on the wood and long screws are used to install with no extenders. This is a clear violation but with the cover on who knows?
Posted By: sparkyinak Re: Microwave - 08/30/08 02:40 AM
The inspector who removes the cover.
Posted By: renosteinke Re: Microwave - 08/30/08 06:00 PM
S, that's a very good point!

A cabinet showroom recently opened, and they carefully re-mounted the existing wall receptacles inside the cabinets. That is, they took the devices out, made exacting holes in the cabinet backs, then mounted the devices to the cabinet back.
This is a violation of the 'zero clearance' required if the surface is combustible. The issue can be resolved with the use of those plastic-sleeve box extensions.

Naturally, this is not an issue when the entire box is brought forward and mounted to the cabinet ... or when a deep mud ring projects out from the wall enough to enter the cabinet.
Posted By: SteveFehr Re: Microwave - 09/04/08 10:45 AM
What are the flash points of blue carlon plastic and cabinet wood? I have to wonder if there is much of a difference.
Posted By: HotLine1 Re: Microwave - 09/04/08 12:07 PM
Steve:
UL says '2-Hr wall' and others are 2-hr wall, 1-hr ceiling on rated assemblies.

BTW, the Arlington plastic extenders (1-gang & some others) are also UL rated for FR assemblies.

Hope this helps
Posted By: SteveFehr Re: Microwave - 09/04/08 04:11 PM
I'm curious... has anyone ever tried to burn one? I find it hard to believe that those boxes would last 2 hours in a fire. I imagine the wall rating has more to do with the size of the hole being too small for significant flame penetration, kind of like how smoke rolls in the corners of rooms and won't set off fire alarms too close to the wall or ceiling.

I keep talking about it, but one of these days, I'm actually going to build a 2x4 wall with fiberglass insulation and boxes and all, and light that sucker up to see what happens. Might even plug #14 romex into a 60A outlet to test that, too smile
Posted By: renosteinke Re: Microwave - 09/04/08 04:27 PM
Perhaps a more complete explanation is needed here ...

Fire testing of wall assemblies focuses on the wall keeping the fire on one side - that is, the unexposed side of the wall may not exceed a certain temperature during the test. The side of the wall exposed to the fire is typically completely destroyed within the first half hour of the test.

There are additional standards for things like the plastic used in electrical boxes. One of the tests is pretty straightforward; a sample has one edge briefly exposed to a flame, to see if it ignites ... and, if so, what happens when the flame is removed, and how fast the flame progresses up the sample. Pass this test, and the material is considered 'non combustible,' at least as far as the NEC is concerned.
Posted By: HotLine1 Re: Microwave - 09/04/08 08:48 PM
Thanks, Reno
Posted By: SteveFehr Re: Microwave - 09/08/08 10:54 AM
Do you know what the procedure for the flame test is? I'm curious if cabinet wood (solid or MDF) or even sheathing plywood passes. When I think of "combustible" material in relation to storage, etc, I think of old paint cans and oily rags, not wood.
Posted By: renosteinke Re: Microwave - 09/08/08 01:10 PM
I don't recall the exact details, but here is what I do remember ...

The sample - think a piece maybe 1" wide and 6" long - is held at an angle just shy of vertical. A large Bunsen burner is then placed under it, with the flame in contact with the lower edge for a brief period. Then the results are observed.

NOW ... for the bad news ..... this simple test has been shown to be essentially worthless in evaluating the actual fire behavior of materials. Only in the crudest manner does it provide any real means of comparing the hazards posed by the materials.

For example, nearly any wood product will ignite, and the flame will march up the face of the material. Eventually all the wood will be consumed. Simple, clearly flammable foam insulation will pass, though, as the material melts and falls to the bench as soon as it gets warm; the remaining sample is too far from the flame to ignite.

I do not recall the particular manner in which test results are 'scored.'
Posted By: Niko Re: Microwave - 10/21/08 09:34 PM
Eventhough some argue that cord is exposed, but in realty all the items that usually go in the cabinet above the built in microwave are things that will not in any way damage the cord. besides most microwaves get installed flush on the top and at the back and the cord comes off of the top of the unit. So the only way it can be installed is through the hole that is made on the bottom shelf of the cabinet.

I guess this can also fall under the gray area where the AHJ must make the final decision.

Edward
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