Double Oven Shares Neutral And Ground?

gravtyklz

I installed a double oven today that had a crimp sleeve crimped around the neutral and ground. Thats the first ive seen an appliance like that so I looked at the instructions to see what they explained about it. All it said though was that if you only had 2 conductors and a ground to use it like it is but if you had 3 conductors and a ground to seperate the ground and neutral.

Is this considered safer because its a dedicated circuit?

Celtic

"This" being which???

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JohnJ0906

That is for the oven being used as a replacement for an existing (3 wire - 2 hots/1 neutral) installation.

For a new installation, you would cut the crimp off. 4 wire feed. 2 hots, 1 neutral, 1 EGC.

Every oven I see comes like this - wired 1 today in fact.

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John from Baltimore
"One Day at a Time"
All replies based on the 2008 NEC

gravtyklz

Most of the ovens i've wired I usually have to wire the cord myself but this wone already had the one I explained above.

After the wonderful discussion of using a ground as a neutral, I was just surprised to see something newly manufactured that was prewired to use a ground as a neutral.

This is a remodeling trip out and I have a 10-3 wire in the j-box, so obviously I seperated the neutral and the ground. I was just wondering how they justify combining the neutral and the ground? Do they just consider it to be the same as the old range/ovens that use 2-110 conductors and 1 ecg?

Celtic

When they come pre-wired/connected - how is the factory/warehouse monkeys supposed to know if the appliance is a "new" install, "existing" install or what?


It's all covered in 250.140 ...and the manufac. do ship with a big-azz orange sticker to get your attention.



"They" don't have to justify it ...."they" don't know - nor care or need to - what the units final resting place will be.

WTF is 2-110 conductors???

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Speedy Petey

The old oven/range circuits did NOT have only "two 120v" lines and a ground. They had two hots and a NEUTRAL. In these older range, oven and dryer circuits the ground was bonded to the neutral. There was NO egc. The neutral served BOTH purposes.

The ONLY time the neutral was bare is when SEU cable was used, and it was used a LOT.

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Sparky Joe

They don't have to care because the device/appliance is listed for them to do that.

What's the difference between building something on site and buying something factory built..........The all mighty Code Book.

Celtic

Are you saying factory built does not follow NEC at all?

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gravtyklz

none at all, this was just the first time I saw an appliance wired this way from the factory.

gravtyklz

That explains a lot then. Does the same still exist for water heaters, heat pumps, well pumps, and air handlers?

Sparky Joe

Just the last 2 words of that question scream "no". All 'constants' of any question mean the question is false (in the test sense anyway).

All I'm saying is build something, send it to UL, get it approved for it's intended use, and you've superceeded the NEC.

Don't know the article off the top of my head, but it's in there.

Celtic

It was a loaded question good catch.

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Speedy Petey

No because they are mainly straight 240v appliances and do NOT require a neutral, as opposed to 120/240v which does require a neutral.
Unless of course they are 120v.


You need to get a LOT of basics down. Things like knowing the difference between "120v", "240v", and "120/240v".

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gravtyklz

I agree i've been trained by "grand fathered" electricians who know how to wire by code, but i've leaned very little theory in my time.

I think I'm going to look into Mike Holt's electrical theory materials since hes esteemed so high here.

send_it_all

That's a good idea. In the mean time, you should focus on the excavation side of the business. Electrical is the one of the few trades where even slightly overstepping your boundary of knowledge can have catastophic results.

gravtyklz

Well I may ask strange questions on here, but i've yet to overstep any boundries.

i've asked questions on here so I understand why things are what they are.

DaveTap

Actually its not considered safer... its done because they assume most ranges are replacements for existing units in houses built before a seperate neutral was required.

In the old old days electric ranges just had 240V heating elements and no neutral was required... but then someone came up with the idea of adding lights and timers... which were easier/cheaper to buy in 120v. In order to make them work they merely attached them to the ground figuring neutral and ground were bonded together in the panel anyway... and for most installs with NM it wasn't a problem (as long as there was a good ground the small amount of current from the clock and light were relatively inconsequential). The problems started with metal conduit installations... (since the conduit was now being used as conductor) and aluminum or Non Metalic NM cable (aka Romex)...

Anyway if they don't bond the neutral to ground on a 3-wire installation the light and timer won't work.

Of course now we have to correct this by running and extra conductor (usually 6 or 8 awg even though it'll never see more than 2 amps)... just because the stupid manufacturers wanted to save a few bucks by not using 240v lights & timers, or a small step-down transformer

gravtyklz

Perfect explanation....thanks a lot!

Andy in ATL

Keep asking and ignore the naysayers.... I think people used to tell me there is no such thing as a stupid question.

tmdelisle

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