Wall oven wiring - Type SE, Style R

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Old 07-17-13, 11:14 AM
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Question Wall oven wiring - Type SE, Style R

Hi guys. I am replacing the original wall oven in a house built in 1987. I was originally confused by the wiring coming into the oven's receptacle, but was told (on the phone) by an electrician that the wire sounds like Aluminum Type SE, Style R with 2 black hots and a bare twisted, stranded ground. They indicated to connect the oven's two hots (black and red) each to one of the black hots, and to connect the oven's neutral and ground to the large stranded ground in the receptacle. I did as he indicated and the oven powered and heated, but I wanted to get a second opinion before installing the oven and enclosing the wiring into the wall. Is this acceptable wiring? Please see the attached picture for the wires I mentioned. Thanks in advance for the advice!

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Old 07-17-13, 11:56 AM
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Hate to break it to you but that box is too small, there are no connectors on the cable and those wire nuts are not for aluminum cable. The box is not grounded either.

That is SE-U, not SE-R.
 
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Old 07-17-13, 12:18 PM
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Thanks for your reply, pcboss. I should have mentioned that I am going to add the cable connector and aluminum nuts before enclosing in the wall, I was just testing the wiring configuration that was recommended to me. But I wasn't aware that the existing box for the oven was undersized. What size box is required for a wall oven?

Is the oven wiring that was suggested to me (oven's neutral and ground to stranded ground) allowed in replacement situations?
 
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Old 07-17-13, 04:36 PM
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I am going to add the cable connector and aluminum nuts before enclosing in the wall [box].
You need two connectors, one for each cable. Also, there are no wire nuts made that can be used as part of connecting aluminum wire to copper wire. You need to use something like a Polaris connector, that prevents the two metals from touching each other, if you keep that wiring from the panel.

What size box is required for a wall oven?
It has nothing to so with the oven. It is a function of the number, size and configuration of the conductors, clamps and devices in the box. While it's impossible to give you the exact answer without knowing the size of each conductor, a deep 1900 box (4" square box) with a raised cover for the receptacle would probably work.

Is the oven wiring that was suggested to me (oven's neutral and ground to stranded ground) allowed in replacement situations?
Possibly. It depends on the requirements adopted by your local jurisdiction - you'll have to ask them.

The best solution is to replace the SE-U cable with Type NM cable with the proper size and number of copper conductors, protected with the properly-sized breaker.

What size are the wires in that cable, what size is the breaker for that circuit, and what is the maximum overcurrent protection specified for your new oven?
 

Last edited by Nashkat1; 07-18-13 at 02:48 PM.
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Old 07-18-13, 09:18 AM
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Lightbulb

Thanks for all the good info, Nashkat.
You need to use something like a Polaris connector, that prevents the two metals from touching each other, if you keep that wiring from the panel.
Are the Aluminum-to-Copper wire connectors sold locally inadequate for this type of joining? (Link below) I've never used a Polaris connector before.
Aluminum-to-Copper connector
What size are the wires in that cable, what size is the breaker for that circuit, and what is the maximum overcurrent protection specified for your new oven?
The existing Aluminum Alloy SE-U cable is 6 gauge, the breaker is 30 amp, and the Electrical Requirements for the oven are listed as 240V | 6.8KW | 30 Amps.

Thanks again for all the advice, gentlemen.
 
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Old 07-18-13, 09:42 AM
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Are the Aluminum-to-Copper wire connectors sold locally inadequate for this type of joining? (Link below) I've never used a Polaris connector before.
Aluminum-to-Copper connector
There are two problems with the purple Ideal #65 Twister connector. The first problem is they will not work on #6 conductors and the second problem is they have an extremely high failure rate by directly connecting aluminum to copper conductors. They ARE NOT APPROVED by the Consumer Product Safety Commission and were never intended for connecting loads higher than that of a light fixture to aluminum conductors. The Polaris or equivalent connector is an approved connector and does not bring the aluminum and copper conductors in direct contact. ILSCO makes a very similar connecter. As far as I know, you won't find these connectors at a big box store, but they are usually readily available at most electric supply houses.
 
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Old 07-18-13, 11:39 AM
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Unhappy

Thanks, Joe. Although it sounds like I could possibly make it "work" with the existing wire, all of the input is leading me in the direction of running a new NM cable to the 30 amp breaker. The next question would be, what size NM should I run for the 60 or so feet of cable that would be needed? I believe a 30 amp 220 circuit would typically require 10-3?

It would appear that I was overly optimistic about the ease in replacing an '80s oven with a modern one. And now the worst part is that I get to explain to the wife why the new oven can't go in right away like I told her it would, and why the old oven is already in the dumpster.
 
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Old 07-18-13, 12:00 PM
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Actually it would be a 120/240 circuit not 220 and yes 10-3 would be the choice. I'd probably consider 8-3 to future proof against a larger oven later. Either size wire breaker would be 30 amp.
 

Last edited by ray2047; 07-18-13 at 01:15 PM.
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Old 07-18-13, 12:47 PM
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Thanks, Ray. That sounds like a good idea. You guys are a wealth of knowledge and have been very helpful.
 
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Old 07-18-13, 03:00 PM
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Are the Aluminum-to-Copper wire connectors sold locally inadequate for this type of joining?
You might say that. In addition to the information Joe posted, here's a comparison sheet from an installer and one from a manufacturer - with pictures. Click on the pics for a close-up.

all of the input is leading me in the direction of running a new NM cable to the 30 amp breaker. The next question would be, what size NM should I run for the 60 or so feet of cable that would be needed? I believe a 30 amp 220 circuit would typically require 10-3?
It's a 120/240V circuit, as Ray said.

The size of the wire and the size of the breaker are determined by the load.
Originally Posted by Nashkat1
what is the maximum and/or minimum overcurrent protection specified for your new oven?
 
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Old 07-18-13, 04:23 PM
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the Electrical Requirements for the oven are listed as 240V | 6.8KW | 30 Amps.
The required circuit is just 240 volt.

10-3 would be the choice. I'd probably consider 8-3 to future proof against a larger oven later. Either size wire breaker would be 30 amp.
I agree with ray to future proof your installation. You will not need the white neutral conductor, just cap it off at both ends, but the white may be needed in the future if a replacement oven would require 120/240 volts.
 
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Old 07-18-13, 04:41 PM
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Oops, I missed the spec. I agree with Joe and Ray.
 
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Old 07-19-13, 10:52 AM
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Thanks, all. I am going to run the 8/3 to the breaker tonight, and hopefully have the new wall oven installed by tomorrow. It worries me that the electrician I originally spoke to didn't mention any of the valid concerns which you guys noted.
 
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Old 07-21-13, 08:56 AM
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Curious Nashkat1, was just thinking after looking at all these pictures of bad aluminium splices, what if one took the time to solder aluminum or even copper to aluminium, i would think that type of connection would hold up quite well undisturbed, I myself am not a fan of soldering, I know alot of people that feel the need to solder literally everything on car projects or whatever they are working on.
 
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Old 07-21-13, 11:22 AM
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IDK, braether3. I've done almost no soldering. It might work, but the problem, as I understand it, is galvanic corrosion resulting from placing these two metals in contact with each other.

I've wondered for some time why using a crimped barrel connector wouldn't work.
 
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Old 07-22-13, 11:38 AM
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The dis-similar metals cannot touch so soldering would not be allowed.
 
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