3-wire 240V conversion - ground to water pipe?

[Duemeister]

Hi folks. I have a different twist on an old maneuver - converting an unused 240 connection to 120. The 10 gauge wiring is black-red-white no green ground. I have a small subpanel with a couple of 120 breakers to step it down. But I think I need a ground wire to make it legit to U.S. code. However, there is a copper pipe within reach of my new subpanel. It even has a ground strap already on it (see in the background of the picture).

Can I make my ground connection to the copper pipe so I don't have to pull a new 4-conductor wire?

 

[Firebrick43]

No! It’s against code to not run a ground wire.

 

[wyliesdiesels]

No dont do that.

You dont know the integrity of the water line all the way back to the panel.

What happens if the bond to the pipe becomes compromised? Then you lose the safety your EGC provides

What do the wires on the clamp connect to?

 

[Duemeister]

I was afraid you would say that. This is a fixer-upper house. So I don't know where that ground strap goes. Dammit. I guess I'll have to pull a 4-conductor line. Seriously miserable in this situation. The work space in the attic is miserable.

Thanks for keeping me out of trouble!

 

[PCustoms]

I was afraid you would say that. This is a fixer-upper house. So I don't know where that ground strap goes. Dammit. I guess I'll have to pull a 4-conductor line. Seriously miserable in this situation. The work space in the attic is miserable.

Thanks for keeping me out of trouble!

Any chance the ground wire just got snipped off at the jacket?

 

[75gmck25]

You do have three wires that could be used for hot, neutral and ground, but they are not the correct color.

I know you can remark a white wire to show it as hot, but I'm not sure you are allowed to mark a red wire to show it serves as ground. It would be electrically okay, but probably not code compliant, and would confuse any electrician that ran across it in the future.

I also recommend checking inside the wire jacket to make sure there isn't a ground wire hiding in there.

 

[Duemeister]

Any chance the ground wire just got snipped off at the jacket?

Good question. I thought it was a four-conductor when I was rerouting it because it is a thick cable. After I trimmed it and stripped it back I was surprised to only find the red-black-white in the picture.

 

[PCustoms]

Good question. I thought it was a four-conductor when I was rerouting it because it is a thick cable. After I trimmed it and stripped it back I was surprised to only find the red-black-white in the picture.

Well if you stripped it you would have seen the ground

 

[mike93lx]

If that was my house, I'd be stripping the insulation off the red on both ends and using it as a ground

 

[Norcal]

That is not "3-wire 240V", it's 120/240V.

 

[Duemeister]

That is not "3-wire 240V", it's 120/240V.

The original installation was connected to an outdoor electric range top and wired to a 30 amp 240V breaker in the main panel.

 

[Norcal]

The original installation was connected to an outdoor electric range top and wired to a 30 amp 240V breaker in the main panel.

Ranges are 120/240V, not 240V.

 

[Crazyjake8493]

The work space in the attic is miserable.

Get yourself a battery fan. I keep a Klein in my truck that gets used a lot. Has a clamp, keyhole, and magnets to mount it. I also use a Milwaukee M18 that will run forever with one of the big batteries in it.

 

[Sno-Pro]

If that was my house, I'd be stripping the insulation off the red on both ends and using it as a ground

This is your answer.

 

[Ry24000]

your looking for 120 volt. check that cable to see if the grounding conductor is in there.(for whatever reason some installers liked to snip them off) If not use the red conductor as the equipment ground, wrap some green tape on it at both ends, land it on the proper ground terminal and viola you have your 120 volts. Please don't remove the red insulation. waist of time. if you do strip it completely be careful of where it is routed.

 

[mike93lx]

your looking for 120 volt. check that cable to see if the grounding conductor is in there.(for whatever reason some installers liked to snip them off) If not use the red conductor as the equipment ground, wrap some green tape on it at both ends, land it on the proper ground terminal and viola you have your 120 volts. Please don't remove the red insulation. waist of time. if you do strip it completely be careful of where it is routed.

Finding the roll of green tape and wrapping it will take longer than stripping the insulation. But six one, half dozen of the other

Not sure why any extra care would be needed in this case. An EGC in NM is always bare anyway

 

[Ry24000]

Finding the roll of green tape and wrapping it will take longer than stripping the insulation. But six one, half dozen of the other

Not sure why any extra care would be needed in this case. An EGC in NM is always bare anyway

Typical homeowners and stripping wire Hmmmmm......................
Yeah your right green tape would require a trip to the hardware store.
Just giving the guy options from a guy with 32 years of electrical experience.

 

[Duemeister]

Mission accomplished folks. Thanks for all the great advice. I played it safe and just used the 3-wire for a plain old 120V sub panel and gave up on the 120/240V original idea.s (Did I say it right this time Norcal?) I bought some 4-strand 10-3 to run a new line but couldn't get it past the already crammed raceway to the attic. Florida also makes us run everything in a potentially damp condition (which is almost everywhere) on a GFCI, so I have that installed in the main box for the entire bench circuit. I really didn't need the sub panel complexity but I already had the hole cut for it and the box, so I left it. A little redundant but it might come in handy later. Now we'll see how the IKEA cabinets hold up.

 

[Duemeister]

Oh yeah, and I bought a roll of green tape to mark that ground properly. Probably never use it again.

 

[mike93lx]

Typical homeowners and stripping wire Hmmmmm......................
Yeah your right green tape would require a trip to the hardware store.
Just giving the guy options from a guy with 32 years of electrical experience.

Let's call it what it is. They are equally hack

 

[wyliesdiesels]

The original installation was connected to an outdoor electric range top and wired to a 30 amp 240V breaker in the main panel.

Ive never seen a range with 240v controls…. Its 120/240v

 

[Duemeister]

Electricians - help me understand this. Some of you are saying that I couldn't have had a 240V connection running to an outdoor range. It must have been 120/240v. I think that is also known as "split phase" because one wire is a phase of 120 and another wire has another phase of 120 and when you add them together you get your 240. And, because they are running out of phase from each other, they inherently ground each other making a return neutral unnecessary. So a three-wire connection is sufficient. Is that what you are saying? OR, was my old three-wire configuration really a 240v connection as I originally stated, specifically because it only had three wires in the first place. The breaker was very clearly a labeled 30 amp and was a double-wide breaker. The black and red wires connected to the breaker and the white wire went to the neutral/ground bus bar in the main box. No fourth wire. The appliance on the other end was a 30-year old Jennaire outdoor downdraft grill/stove. It was hardwired to those three wires, not plugged in like an electric dryer.

So - was that a 120/240v connection or a 240v connection?

 

[larry4406]

My original 240V electric range was wired with 3-wire conductor (black, red, white). Inside the oven at the cord junction box, there is a copper ground bar jumper that connected the oven frame to the white conductor. This is old school.

When we rewired, the wire was upgraded to 4-wire (black, red, white, ground). Had we kept that range, it would have been changed to a 4-prong plug and the ground jumper removed.

 

[Norcal]

Electricians - help me understand this. Some of you are saying that I couldn't have had a 240V connection running to an outdoor range. It must have been 120/240v. I think that is also known as "split phase" because one wire is a phase of 120 and another wire has another phase of 120 and when you add them together you get your 240. And, because they are running out of phase from each other, they inherently ground each other making a return neutral unnecessary. So a three-wire connection is sufficient. Is that what you are saying? OR, was my old three-wire configuration really a 240v connection as I originally stated, specifically because it only had three wires in the first place. The breaker was very clearly a labeled 30 amp and was a double-wide breaker. The black and red wires connected to the breaker and the white wire went to the neutral/ground bus bar in the main box. No fourth wire. The appliance on the other end was a 30-year old Jennaire outdoor downdraft grill/stove. It was hardwired to those three wires, not plugged in like an electric dryer.

So - was that a 120/240v connection or a 240v connection?

Prior to the adoption of the 1996 NEC it was permitted to ground the frames of clothes dryers, & cooking equipment, to the neutral, there was no grounding conductor. Those appliances used 120 volt components so a neutral is required.

 

[dave*99]

Electricians - help me understand this. Some of you are saying that I couldn't have had a 240V connection running to an outdoor range. It must have been 120/240v. I think that is also known as "split phase" because one wire is a phase of 120 and another wire has another phase of 120 and when you add them together you get your 240. And, because they are running out of phase from each other, they inherently ground each other making a return neutral unnecessary. So a three-wire connection is sufficient. Is that what you are saying? OR, was my old three-wire configuration really a 240v connection as I originally stated, specifically because it only had three wires in the first place. The breaker was very clearly a labeled 30 amp and was a double-wide breaker. The black and red wires connected to the breaker and the white wire went to the neutral/ground bus bar in the main box. No fourth wire. The appliance on the other end was a 30-year old Jennaire outdoor downdraft grill/stove. It was hardwired to those three wires, not plugged in like an electric dryer.

So - was that a 120/240v connection or a 240v connection?

You had a 3 wire 120/240 connection. And no ground wire. Likely your appliance had the white (neutral) connected to the chassis. Today, we need to use 4 wires for a 120/240 appliance. Ground wire connects to chassis of the appliance. White (neutral) connects to the controls/clock/motor/light - whatever needs 120 inside the appliance.

Here is an example of a 50A system in 3 and 4 wire configurations.

 

[alfredeneuman]

I'd be stripping the insulation off the red on both ends and using it as a ground

Unless the wire is #4 or larger that would be a violation of the NEC

 

[wyliesdiesels]

Unless the wire is #4 or larger that would be a violation of the NEC

not when its conductors in NM cable. code allows you to tape them...

 

[Duemeister]

Prior to the adoption of the 1996 NEC it was permitted to ground the frames of clothes dryers, & cooking equipment, to the neutral, there was no grounding conductor. Those appliances used 120 volt components so a neutral is required.

Thanks Norcal. That makes sense. The house was built in 1992 and I'm sure that old stove was part of the original build.

 

[Model A Fan]

Typical homeowners and stripping wire Hmmmmm......................
Yeah your right green tape would require a trip to the hardware store.
Just giving the guy options from a guy with 32 years of electrical experience.

He's already got the green tape. Just look at the photos!

 

[Glemon]

Not an electrician, but regarding marking a red wire green and any confusion about the wire's identity. I think I would be much happier thinking a wire was hot and finding out it was a ground, than thinking it was a ground and finding out it was hot.

Also, if I am a red wire that identifies as green I think that is ok now...I will see myself out...

 

[PCustoms]

So what is this mystery 3 wire NM material that doesn't have a ground?

"Is 10/3 without ground" available?

 

[wyliesdiesels]

So what is this mystery 3 wire NM material that doesn't have a ground?

"Is 10/3 without ground" available?

it used to be....

 

[PCustoms]

it used to be....

I'm a little out of it today, but what application has 2 hots and neutral?

 

[wyliesdiesels]

I'm a little out of it today, but what application has 2 hots and neutral?

try reading previous posts... 3-wire stove and dryer receptacles prior to 1996 code cycle... look at nema 10-30 and 10-50 receptacles for dryers and stoves respectively... 120/240 no grnd...

 

[PCustoms]

try reading previous posts...

I did

Sorry I didn't put two and two together, my brain is pretty foggy but the allergy and cough meds...

 

[Ry24000]

I'm a little out of it today, but what application has 2 hots and neutral?

Range, dryer, hot tub, Jacuzzi tub, sauna, floor heat, emergency power receptacle.
I could be wrong about the floor heat though.

 

[larry4406]

Range, dryer, hot tub, Jacuzzi tub, sauna, floor heat, emergency power receptacle.
I could be wrong about the floor heat though.

At the day job, many of our heated floors are 240V 20A. Line1, Line2, and ground.

 

[Norcal]

Range, dryer, hot tub, Jacuzzi tub, sauna, floor heat, emergency power receptacle.
I could be wrong about the floor heat though.

All the loads with the exception of cooking equipment & clothes dryers required a grounding conductor, not a neutral.

 

[wyliesdiesels]

Range, dryer, hot tub, Jacuzzi tub, sauna, floor heat, emergency power receptacle.
I could be wrong about the floor heat though.

Ive only seen 3-wire no grnd NM used on the first 2, never the others.... you wouldnt use it on 240v floor heat either. wrong application... and all of those required a grounding conductor.... as said above by norcal

 

[wyliesdiesels]

At the day job, many of our heated floors are 240V 20A. Line1, Line2, and ground.

which wouldnt be using 3-wire/no grnd NM cable