New range - 3 wire connection

[Kleggo]

Hi all,

I just purchased a Kenmore induction slide-in range and have questions about the electrical connection. The panel has 2 40 amp breakers designated for the range. The house was built in 1989. When I pulled the old range out, it was connected directly to a 3-wire cable that was labeled:

E-90490 (UL) 3 CDRS AWG 6 COMPACT AL TRIPLE E ALLOY TYPE SE CABLE STYLE U TYPE XHHW CDRS 600V

One wire is insulated black, the other is black with a reddish stripe, and the ground is bare.

Reading this link - http://www.terrylove.com/forums/showthread.php?t=19552 - I think that 1-3 of the exceptions to NEC 250.140 apply, but I'm not sure about #4 or how to check that one.

The range installation states either 3-wire or 4-wire installation is permitted, although it recommends copper. Here's my questions.

1) Does the 3-wire exception apply? How do I validate all 4?

2) What are the cons of using 3 wires vs. 4?

3) Do the wires really need to be copper?

Personally, I'm leaning towards pulling a new line, although I have no idea how painful that would be. It just seems like the right thing to do given the anomolies. Am I being paranoid, and the 3 wire cable will be fine?

Any advice?

Thanks,
K

[jimbo]

A true 240 volt load only needs 3 wires...2 hots and a ground. White neutral not needed.

Your range may be a true 240 volt load. You need to check the instructions.

A lot of electrice dryers, and ranges, are referred to as 120/240. That is, parts of the appliance like perhaps motor or timer, are 120 volt. The "big heat" is 240. Those appliances need a NEUTRAL wire. In the past, the neutral was allowed to be connected to chassis and also serve as ground. On new installs, for some years, that is not allowed, but if you had an existing 3 wire stove or dryer, you could connect a new one on that 3 wire.


So you need to figure out what your new stove really needs.

[Kleggo]

The instructions don't specify "true 240v load". In several places, the booklet does state 120/240.

Thanks,
K

[jadnashua]

If that cooktop needs 120 in addition to 240, then you need to run a new cable to provide the 4-wire connection required. You can't use a bare wire for the neutral.

[Kleggo]

The instructions are vague on whether 120v is needed. However, there is a section that shows how to install 3 wires, using ground for neutral. Would that indicate 120v is not required?

[jimbo]

The instructions are vague on whether 120v is needed. However, there is a section that shows how to install 3 wires, using ground for neutral. Would that indicate 120v is not required?

No, that would indicate that 120 IS required. And your problem is this: under certain "grandfather" conditions, you can use the neutral as the ground. But, you definitely CANNOT use the ground as the neutral.\

There should be detailed wiring installation instructions included. If not , call the company.