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I just got a brand new electric oven and I'm having some trouble connecting it myself. It's a conduit installation, so the delivery service wouldn't touch it. I got everything working on the first try, but that was not to last.

  • I moved it a little and the clock went out instantly and the oven can't be turned on. Cooktop still works fine.
  • Reached behind the oven and felt a light current on the flexible conduit!
  • Wiring looks fine, I've redone it.
  • Touched back housing of the oven and the exterior flexible conduit and there is a current!

So I'm figuring this is the problem, but I have no idea how that could be the case and my electrical knowledge is too minimal to puzzle it out much more.

Does this mean there is a wiring problem inside the conduit possibly? How do I test for that? A voltage meter shows 240 if I hit the red and black wires, 120 if I hit the black and the conduit or the red and the conduit. Should that carry voltage at all when testing with the meter? Did I have a grounding problem before when it was all hooked up to the stove? I'm so lost…

Everything is turned off and the breaker is off, etc. until I can think of some other scenario to test. I opened the nearest box before the wires go into the conduit and no wires appear exposed, but I'm wondering if something is happening inside the flexible conduit like a wire is exposed and touching the conduit? photo of wires while disconnected

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    Does this hook up have a neutral or a ground? – JPhi1618 Jun 6 at 20:45
  • It's a three wire connection. Red, Black, and Ground. No Neutral. Also hooked up to 50 amp breaker, for what it's worth. – jeffhot Jun 6 at 20:46
  • Is the ground bare? And voltage between ground and the conduit or oven chassis? – JPhi1618 Jun 6 at 20:47
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    The range has a white wire in the center of the connection block. This suggests to me that it needs a neutral. Right now the chassis ground is connected to the center terminal with a bridge, right? So right now you would using the chassis ground as a current path for the neutral side. This is not right. Check the instructions. – Jim Stewart Jun 6 at 21:14
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    Or I guess if there is a neutral in that junction box I can possibly run a wire off that through the flexible conduit to the stove if I can manage the cable routing. – jeffhot Jun 6 at 23:27
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Your description of red, black and conduit indicates that you do not have neutral but just ground via conduit. That is NOT a good thing. A little background:

Ovens, cooktops, etc. typically need 240V for heating elements but 120V for lights and controls. In order to get 120V, you need a neutral wire (normally white).

In the old days, there was a neutral but often no ground. So ground would piggyback on neutral. That was OK from the perspective of normal usage but a bit problematic if things go wrong in certain ways. So now (actually for many years), a 4-wire connection - hot, hot, neutral, ground (ground can be via metal conduit though, doesn't have to be an actual wire) is required.

But often stoves (and dryers) are still hooked up to a 3-wire connection. A 3-wire connection wouldn't be so bad if it were "ground piggybacked on neutral". But you have the opposite - neutral piggybacked on ground. That is not a good thing.

The solution is to install a proper cable. It must be the right size for the breaker & device (that would probably be 8 AWG) and include two hots, neutral and ground. Alternatively, if you are running individual wires in metal conduit with the conduit acting as ground then you can use three individual wires, two hots and neutral.

Updating based on pictures:

You have a 4-wire connection on the oven. However, there is a "copper bridge" to connect neutral (white) and ground (green screw). You could do that in the old days. But current code says you should:

  • Have a 3-wires + ground connection. Ground can be green or bare (including possibly the conduit itself) but it neutral can not be green. So that means you need to add a white wire for connecting to the white terminal on the oven.
  • Remove the "copper bridge". That is a must. The instructions discuss using the copper bridge for the situation where you don't have a separate ground and instead rely on neutral. But in your case, you don't have a separate neutral and instead are relying on ground! You can't do that!

Run a new white wire through the conduit. Remove the copper bridge. Connect black, red, white, green to matching places on the oven. Then see if there are any remaining problems. But the current installation (no neutral) is WRONG.

I found the official installation instructions (PDF). Follow the 4-wire instructions in step 6, not 3-wire step 5.

What is a bit strange, which I don't quite understand, is that the 4-wire instructions for a Power Cord specifically say "Cut and discard the ground strap." But the 4-wire instructions for Conduit do NOT say to do that.

  • Wouldn't it be strange to have a range wired with only 240v and a ground? This is what I was suspecting, but I would want to trace that green wire and see what it's actually connected to - it could be a neutral and they used the wrong color. – JPhi1618 Jun 6 at 21:01
  • This is interesting and has reminded me of 2 things and maybe 1 bad idea: My old range was hooked up with the ground to ground and not to this neutral connection that would be used in a 4 wire connection. I did that at first, just wired the new one like the old one. But then I read the manual and they were really insistent that ground needed to go to the center connection and the copper bridge connect to the ground screw. Would it be a terrible idea to not follow the manufacturer's advice and instead remove the copper bridge from ground to neutral and connect the ground directly? – jeffhot Jun 6 at 21:09
  • @jeffhot Are you suggesting connecting the ground, but leaving the neutral on the range not connected to anything? You really can't do that. – Someone Somewhere Jun 7 at 11:16
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    I was suggesting that but I've abandoned that plan. Gonna add a neutral wire and then go to a four wire connection. – jeffhot Jun 7 at 19:38
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Just seen your pic. New code you should have a 4 wire to the range. There are codes that say if not, you are still ok. The flex could have cut the wire, due to missing anti short at end of flex. Look for that. The range should have a range recpt. And a range cord to the range .Thats why they would not hook it up. You could install if you want. And if the wires are damaged, they could be used to pull in your new ones.If you stay with the 3 wire,the clip to ground stays on. If you go new to 4 wire the clip comes off separating ground and neutral. You do not have to have a 4 wire, 3 wire is still code. But if the wires are damaged.And you add new ones.4 wire better and is the new code. If the wires go to a main panel put white tape to re,id ground wire at both ends now thats neutral. If run in conduit use that as ground. Run a#8 lenth of ground wire through the flex to the pull box ,screw onto a ground screw.There is your ground. Now you can install ,4 wire hook up.

  • yeah I need to put a collar on that flex I suppose, if I can get it working at all! – jeffhot Jun 6 at 21:28
  • 3-wire hot hot ground is not code for an appliance which requires hot hot neutral. Especially not in conduit, where you must use the actual correct color of wire. – Harper Jun 7 at 2:35
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    "It's a range or dryer, I can bootleg it" is NOT true. That is legal only where grandfathered in cases where a) it was a hot-hot-neutral b) correct at the time and c) it was installed prior to the outlawing. This fails on a) and b). – Harper Jun 7 at 3:05
  • Totally took this idea to add white tape to the green ground to re-label it rather than running additional wire. – jeffhot Jun 13 at 6:11
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First, you see a brass strap between the neutral terminal and the ground. That must be removed. This is very important to safety.

Now, I can see why they ran screaming. The problem wasn't the conduit, but rather the selection of wires in the conduit. There is no neutral, which this oven may need.

It may be a better plan to take back the oven and get an oven which does not require neutral.

Alternately, you can just try not hooking up the neutral and see if you lose anything you care about. If not, enjoy the oven.

If you really, really need neutral, then it is a simple matter. Conduit is a pipe. You can add neutral. You need to follow it back to the service panel and figure out the route. In principle each corner should have an access cover. Then obtain a neutral wire, use 8AWG, and thread it down the pipe. This can be tedious and maddening without the right tools. It may be worth bringing in an electrician because it's a 5 minute job with the right tools.

  • I do not agree the strap comes off. It is set up for a 3 wire. If it was a 4 wire clip comes off ground goes to frame and neutral is isolated. Yes a 4 wire is better. could tape on a pull rope to old wires pull back, add a neutral, pull back. Shoul d not be hard wired . need recpt. – user101687 Jun 7 at 2:49
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    @RobertMoody you cannot bootleg neutral off ground. The exception in Code that grandfathers old 3-wire connections calls for bootlegging ground off neutral and there is a difference because neutral is not ground. Regardless, this is NOT grandfathered, and a 3-wire bootlegging connection is not legal here, period. – Harper Jun 7 at 2:54
  • I think either of those might work but option A (no neutral) is strongly against the manufacturer's recommendation so I'm going with option B. Tried running a neutral wire myself but the damn ribs in the flexible conduit made that hard. Gonna have a pro do that and then I think I'm good. I'll report back after. – jeffhot Jun 7 at 19:42
  • A bare wire end snags on everything. I put a lumpy bit of tape on it, that often helps. – Harper Jun 7 at 22:58
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TL;DR - I needed a white neutral wire.

Thank you everyone for the assistance on this, I now present the story of how this was all solved. Really appreciate the help as I learned a lot about electric wiring and feel a lot more confident for future jobs in this particular old house.

Basically everyone who said that I needed a neutral wire was correct.

The four-wire installation is preferred, but a three wire is allowed by code if it is pre-existing and it is okay with the manufacturer too. My 3 wire installation was incorrect because my third wire was a ground and not a neutral, plus one more specific piece of information that I had not yet discovered that I will share shortly.

So my plan of attack was, pull a wire back (probably the nice-to-have but unnecessary green wire, just in case it was damaged) with a string on it so that I could pull the new neutral wire through. The nearest junction box had some neutral wire in it, but not of the gauge recommended by y'all for this 240v use, so it looked like I should probably go another length all the way back to the panel with the same technique.

That seemed like a pain in the ass, so I had an electrician come out to quote it and so I could ask him about using the existing neutrals in the nearest junction box. He said no to that and then sent me a quote for almost $800.

That helped me get really motivated to do this all myself. Two friends with electrical experience were staying over so I asked them to help me think this through before I attempted it. Firstly they encouraged safety, turning the main off, etc. Secondly, one encouraged me to pull the front off the panel so we could look in there and see what was what.

That's when I discovered that the ground wire I was using wasn't connected to anything! So this unknown piece of information certainly explains the erratic results I was getting at first.

Ultimately I decided to be lazy. I taped white electrical tape on both ends of the green ground wire and just connected it to the neutral bar in the panel and connected everything in the 3-wire setup as described in the manual (with the copper bridge from neutral to ground in place). And I put a strain relief squeeze collar on the end of the flexible conduit to the stove to be thorough. Everything worked immediately!

Once again, I really really appreciate all the advice and dialog here. I learned quite a lot and feel very enriched by everyone's participation and assistance.

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The stoves with digital controls don’t even need a neutral, they use the 240v as the power source for the power supply on the digital controls.

Pull the stove back out and recheck all your connections.

  • Did all that thrice, I'm wondering more now if the problem is not in the oven but in the conduit? – jeffhot Jun 6 at 20:55
  • If the connections are good then the conduit connection doesn’t matter unless you are using it for the equipment ground. Then it would only matter under ground fault conditions. Something is wrong with your 240v connections if the stove will not power up OR there is something wrong with the stove. Are you getting 240volts to the black and red on the stove? – ArchonOSX Jun 6 at 20:58
  • You said “A voltage meter shows 240 if I hit the red and black wires, 120 if I hit the black and the conduit or the red and the conduit. Should that carry voltage at all when testing with the meter?” Yes, those are the proper readings. Sounds like the stove is faulty if your connections are solid and you have 240 volts on the red and black it should be working. Review the manual to see if there is a jumper or setting for 240 volts instead of 208 volts. That is the only other thing I can think of. – ArchonOSX Jun 6 at 21:04
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    You can't just go by the voltages when there is little or no load. If the ground is being used as a neutral and the ground does not have zero resistance and a high continuous current capacity, then the ground will not work as a neutral should. – Jim Stewart Jun 6 at 21:27

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