Wiring a Wall Oven - Is a Plug/Socket Permitted

[baumgrenze]

For most of 20 years we cooked and baked in our kitchen using the 1950's 40 inch GE Liberator 2-oven range that came with the house when we purchased it. That range had a 3-prong plug on a heavy cord and there was a matching socket mounted on the junction box  wired at 220V. If the stove needed to be moved, it could be unplugged and reconnected easily. During the months of construction our remodel involved this was a daily ritual performed by the construction crew.

When remodeled our kitchen 'it was time' to discard the old and install a new, modern wall oven. Its power cord required that it be 'hard wired' to the wiring in the junction box.

Is this wiring arrangement for the convenience of the manufacturer, or is it required by changes in the uniform electrical code?

I ask because it is clear to me that modern wall ovens need maintenance. Oven maintenance frequently requires that the oven be disconnected and pulled at least part way out of the wall. I know enough about the metallurgy of copper wiring to know that it work hardens easily. This means that every disconnection/reconnection  makes the following one more difficult as the terminal ends of the wires harden. The wires are also harder to stuff back into the junction box.

Does the current code permit the use of the plug/socket arrangement of the 1950's? If it does, it makes sense to me that it would be wise to implement it.

thanks,

baumgrenze

 

[Motorcity Master]

4 minutes ago, baumgrenze said:

For most of 20 years we cooked and baked in our kitchen using the 1950's 40 inch GE Liberator 2-oven range that came with the house when we purchased it. That range had a 3-prong plug on a heavy cord and there was a matching socket mounted on the junction box  wired at 220V. If the stove needed to be moved, it could be unplugged and reconnected easily. During the months of construction our remodel involved this was a daily ritual performed by the construction crew.

When remodeled our kitchen 'it was time' to discard the old and install a new, modern wall oven. Its power cord required that it be 'hard wired' to the wiring in the junction box.

Is this wiring arrangement for the convenience of the manufacturer, or is it required by changes in the uniform electrical code?

I ask because it is clear to me that modern wall ovens need maintenance. Oven maintenance frequently requires that the oven be disconnected and pulled at least part way out of the wall. I know enough about the metallurgy of copper wiring to know that it work hardens easily. This means that every disconnection/reconnection  makes the following one more difficult as the terminal ends of the wires harden. The wires are also harder to stuff back into the junction box.

Does the current code permit the use of the plug/socket arrangement of the 1950's? If it does, it makes sense to me that it would be wise to implement it.

thanks,

baumgrenze

 

Wall ovens are supposed to be hardwired because they are considered "built in". National Electric Code requires any kind of plug, receptical or disconnect to be "accessible". Anything behind a built-in wall oven is not accessible and therefore not allowed. If you are connecting copper to aluminum wires make sure you use the airtight wire caps with the compound. 

There's really no maintenance that will require you to remove the wall oven from the cavity. Sometimes they need to be pulled out for a repair but that's rare and not something you should be concerned about. I don't think I've ever had to disconnect one for service. Usually enough slack to get behind it 

[baumgrenze]

Thank you, Motorcity Master, for you prompt reply.

This oven is mounted under a counter. The junction box is accessible via an opening in the back of the cupboard next to the oven. The 50 inch cord supplied with the oven does not allow it to be moved forward enough to service the oven. Perhaps the manufacturer and the code writers envisioned a junction box located ideally close to the starting point of the oven cord on the oven. This one is diagonally across and several inches beyond the back corner of the opening that holds the oven. Perhaps it could even be considered accessible in code terms.

We required a new control board (bad solder joints) after 8 years. The serviceman also replaced the oven bake element as he had diagnosed that it was not longer functioning properly. My measurement of the resistance told me that it is in spec, but the new one is installed. I watched. This, and any other service will require reconnecting the oven wires with the house wires. I saw how hard he struggled to close the box back up this time.

If I recall correctly, the 240 volt leads that supply the oven are #10 wire, stiff enough in its own right without work hardening. The process he went through won't be tolerated many more times before the terminal ends of the wires break off. The wiring runs through an underslab conduit. Pulling a new replacement wire might work, then again it might not. It was installed in 1955 when the house was built. Tearing out the kitchen cupboards on both sides of the kitchen, jack hammering the floor to get at the wiring, then reinstalling the cupboards and the slate flooring would be prohibitive.

To my mind, resorting to a plug and socket now makes far more sense. The wires from the oven could even be enclosed in shrink tubing if that would make the installation safer in code terms.

thanks,

baumgrenze

[LearningTech]

Needs to be hardwired for national code,  local code,  and the UL listing.

the copper in the whip on ovens is often stranded so can flex without issue.

 It’s not common to remove it, however it is super super uncommon to have to remove the wires fro the box for any matenence or repair. 

It will be at least 50 years before there are any issues assuming it is done right. 

[LearningTech]

2 minutes ago, baumgrenze said:

cupboard next to the oven.

That’s another issue.  The whip fo the oven shouldn’t pass through any wood structure like a cabinet ( depending on local code)

[LearningTech]

4 minutes ago, baumgrenze said:

shrink tubing if that would make the installation safer in code terms.

 

No difference

[LearningTech]

5 minutes ago, baumgrenze said:

won't be tolerated many more times 

Then i would suggest makeing an extension.

go from your box with #10 wire to a new box located in the Proper location ( near the spot on the oven where the wire comes out) and leave  some extra wire. 

 1) the wire is now longer and may not need removal, 

2) if it does then you will be moveing the new wire and not the old one and if it ever did crack off ( which i still think unlikely) then you will have th new wire length to trim and continue, and if it ever came to it then you woul have to connect to the old wire, but this is like 30 disconnects down the road or more, your me and our children are dead by now. So were good. 

[Motorcity Master]

I see what you're dealing with. You are going to want a new juction box behind the oven for sure. It will be a simple extension of your current junction box. The oven manufacturer's installation specs will tell you where the box should be mounted. Don't mess around with a receptical or any other deviation from standard hardwire hookup. You don't want any problems down the line.

[baumgrenze]

A picture is worth many words.

https://imgur.com/a/jfwC4yQ

Text in red in the image (for clarification.)

"The armored cable from the left carries 220 V to to the oven in the adjacent space to the left.
Behind this box cover is the junction 1955 box that had the 3-prong outlet that provided power to the GE range"

The oven is a Bosch HBL3450UC/8. The 36 page "Service Manual" does not show anything about where the power wiring enters the oven.

Are you suggesting wiring a second junction box in the back of the adjacent cabinet?

Here's a try at a second, composite image showing the wall now covered in sheathing and then kitchen cabinets. It shows the approximate location of the oven as a red box. The arm with the black glove is holding the box into which the GE range was plugged to power it.

As you can see, much of the wall behind the cupboards is built-in bookcases in the living room, a clever idea but one that limits possibilities of installing a second junction box.

https://imgur.com/a/CIBFnmg

Where do we go from here?

thanks

baumgrenze

 

 

[LearningTech]

Well your book case limits it a bit. the second box needs to be inside of the oven hole. I guess between the oven and the bookcase.

whats the problem? is the oven hole not deep enough to have the box behind in the same hole as the oven?

if that is the case ( odd) but you can put the second box in the same area as the first one. You wont get the  benifi of being able topul it out, but you will prevent connecting to the old wires and disconnecting often.

 

Your trying to get this perfect, when your install location is not perfect, its not even good.

So you will NOT get a perfect install. (Period). Take what you can get, and have a good install (despite its in a not good location), and call it a win

[baumgrenze]

Thanks for your patience with me and taking time to see the challenges I face.

When I can make time I will try to analyze the available space in the oven box cabinet. The depth should be the same as the cabinet where the connection is now made. The depth of the oven should be in Bosch's specifications. Just now it is bedtime and I am shutting down.

thanks,

baumgrenze

[LearningTech]

No problem goodluck

[baumgrenze]

I found the installation instructions and snipped this image. As it so often the case in image only instructions and manuals it is less than clear to interpret.

https://imgur.com/a/BkGmE1r

I think they are suggesting that the power junction box be 20" up from the floor and offset to the right by 16.5". This is horizontally where ours is, just vertically higher. It would still come through the side of the oven cabinet space, just higher up. I thought that was a violation of code.

Am I reading the drawing properly?

I have no photos of the space with the oven 90% forward out of the cabinet. It would have been hard to photograph in any case.

It would be a doable project to pull the panel on the living room side of the wall and put a box in that high up.

I don't see what it gains. There is hardly space for the whip when the oven is pushed back into the space. Might it loop down and back up?

Does anyone know where I can find a real image of the whip on the back of the oven?

thanks,

baumgrenze

[LearningTech]

1 hour ago, baumgrenze said:

come through 

Nothing “comes through” in the diagram it is all in the same box.

 Its 16.5 inches from LH side. That puts it  right behind the oven 20 inches above bottom of oven.

 So No violation of any code.

Edited November 30, 2018 by LearningTech

[LearningTech]

1 hour ago, baumgrenze said:

what it gains

 

[LearningTech]

On 11/28/2018 at 8:35 PM, LearningTech said:

You wont get the  benifi of being able topul it out, but you will prevent connecting to the old wires and disconnecting often.

It does not gain you any pull out room unless you can get it right behind the oven.

ANY junction box in ANY location gains you the benifit of saveing your old in floor connectors from being moved every time the oven is moved or changed.