OT...wiring question

Uninstalling a set of double ovens in a house. House had a three wire system, two black wires and a bare braided ground. The ovens had four wires, red-black-white-ground. All looks normal but the white wire was twisted together with the two ground wires. There are signs that it got a little toasty in there. Is this configuration correct? If no, how should it have been done When the appliance has four and the house has three wires?

On a 3 wire 220 volt set up you have 2 hot wires and a ground. On a 4 wire you have 2 hot wires a neutral and a ground. In most breaker boxes the ground and neutral are both hooked the the same place. As for whet you have being correct or not I'll not say since I cannot see how things are in the breaker box

To bring it up to code, there would have had to been another cable pulled, 2 lines, a neutral, and a ground.

But many have been wired as you found it. That would not likely have been the source of over heating. The neutral will have very low amp draw, usually for the controls. The 2 lines carry the amperage.

The way it was was proper for the time. Good enough.

Better and current code is to have 4 wires from the breaker box to the device. There may be grandfathered exceptions for installing a new device onto the old wiring....

The heating would be from a loose clamp or dirty wire creating the heat most likely? Poor connection.

Im just a simple dirt farmer, so this is just conversation, not a recommendation.

Paul

Dave, what you describe can be found in many older homes and older appliances, here's the deal

SHORT ANSWER rewire the home and install proper Three Pole 4 Wire Grounding (4 pin) Receptacles for appliances that use 120 as well as 240 like dryers or stoves etc etc that have Three Pole 4 Wire (4 pin) Plugs......


NOOOOOOOOOOOOOOO the Neutral (A GrounDED Conductor) jumped to the Ground (A GroundING Conductor) in a receptacle is NOTTTTTTTTTTTTTTTTTTTTTTTTTTTTT correct !!!!!!!!!!!!!!

The Safety Equipment GroundING Conductor is ONLY for fault current, NOT normal Neutral return current

The Hot Live normal return current carrying insulated NEUTRAL is NOTTTTTTT intended to carry fault current.

Some OLDER appliances that were straight 240 used Plugs (and matching receptacles) with Three Pins, Two Hots L1 & L2 (240 L1 to L2) plus a Safety Equipment (often Bare/Green) GroundING Conductor.

Iffffffff a stove or dryer had (in addition to 240) say a 120 VAC timer or outlet etc., they sometimes used the GroundING Conductor as a substitute Neutral since it was in fact 120 VAC L1 or L2 to Ground so the 120 device worked BUT THEY WERE USING THE GROUND AS A RETURN CURRENT CARRIER NEUTRAL grrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrr but it's ONLY for fault current NEVER normal return current !!!!!

NOTE the reason this works is because in the Main Panel there's a Neutral to Ground BOND............The two Buss, Neutral and Ground are BONDED together.........OR SOMETIMES ONE SINGLE COMMON BUSS IS USED

NEWER appliances that had BOTH 120 as well as 240 internals used Plugs (and matching outlets) that had 4 pins, Two Hots, One True Insulated GrounDED Conductor Neutral, One Safety Equipment GroundiNG Conductor (Bare/Green).

Some older home wiring systems and appliances uses what's called a BOOTLEG GROUND where they jumped the Neutral to the Bare/Green. Thats how a modern appliance with 4 wires may be cheated to work on an older 3 wire system IE they tie/jump the Neutral and Ground NO NO NO

ITS MY ADVICE DO NOTTTTTTTTTTTTTTTTT DO THAT but instead if the appliance has a 4 pin Plug and uses 120 and 240 USE A 3 POLE 4 WIRE GROUNDING PLUG AND RECEPTACLE and run FOUR wires back to the panel, Two Hots, One Neutral, One Safety Equipment GroundiNG Conductor of rated ampacity to a proper rated circuit breaker in the panel

DISCLAIMER Im longggggggggggg retired from Power Distribution Design Engineering so NO warranty but believe this remains true

Hope this helps post any questions. Typically any Electrical or Legal questions draw out the most responses, if any doubt where fire or life safety are concerned don't take just any opinions, but consider consulting trained professional electricians or engineers and the NEC DO NOT take my word for it, I'm too long retired n rusty GRRRRRRRRRRRR lol

Merry CHRISTmas

John T

Thanks John! That was the answer I was looking for. I figured you would come along sooner than later. Have a Merry Christmas!

Youre welcome you got some good responses we pretty much all agreed. There's lots of fine gents here one reason I like this place.......

John T

The supply circuit is 120/240-volt, single-phase, 3-wire; or 208Y/120-volt derived from a 3-phase, 4-wire, wye-connected system.
The grounded conductor is not smaller than 10 AWG copper or 8 AWG aluminum.
The grounded conductor is insulated, or the grounded conductor is uninsulated and part of a Type SE service-entrance cable and the branch circuit originates at the service equipment.
Grounding contacts of receptacles furnished as part of the equipment are bonded to the equipment.