Upgrading 220V wiring - need professional advice!

[Opifex]

The Polaris in the bottom pic is rated 14-4 AWG.

I would need to buy two of these, right? One for the two hot conductors and one for the fused neutral/ground? Would a 3-port work just as well?

 

[Reach4]

That's good hearing! These are semi-custom KraftMaid cabinets, all plywood construction. Unbelievably, the printed installation instructions that came with the cabinets (and posted on the Kraft Maid website) say to drill 7/32" pilot holes into the studs to mount the wall cabinets using the supplied #9 cabinet screws, which are very similar to GRKs but have a larger head. Looking at the size of the drill bit, I was immediately skeptical, and I'm glad I drilled a test hole because the holes are way too big, and there is ZERO bite from the threads! The screw just falls into the hole.

I think it would be important to center the holes into the studs. That has to be hard to get stuff aligned.

I am also wondering about using some metal French cleats. I guess that might move the back of the cabinet away from the wall, but it would sure seem to solve alignment problems.

 

[Sponsor]

 

[Opifex]

I think it would be important to center the holes into the studs. That has to be hard to get stuff aligned.

Yes indeed! The screw holes from the previously installed cabinets are still in the wall. I am using those as a partial reference.

 

[bigb56]

I would need to buy two of these, right? One for the two hot conductors and one for the fused neutral/ground? Would a 3-port work just as well?

No they don't work like that. All the ports are connected. The one in the pic has two ports connected together, the part on top with the rubber plugs is where the set screws are located. So you need 3 of the 2 port.

 

[Opifex]

9/11/25 UPDATE:

So I ran into yet another issue. The double oven is now installed, but the GFCI breaker trips as soon as I attempt to energize the circuit. As a reminder, I have an older 3-wire installation (see pics below). I read elsewhere this could be caused by not removing the bonding strap inside the oven. If that's the problem, well, I think I would rather put in the old breaker than remove the oven again! The owner's manual for my oven (Maytag) has instructions for both a 3-wire and 4-wire system, but it says nothing at all about the grounding strap or the need to remove it for any particular installation. My guess is the neutral and ground are bonded on the oven.

So what should I do? What would you do?

I really do not want to remove the oven again. When the home inspector came out to inspect my install of the 40 amp GFCI breaker, he commented that there could be nuisance trips, and if so, I should just install the old breaker. So it appears that in my area that would be acceptable, despite the fact that my oven is 6 feet from the sink.

 

[wwhitney]

So what should I do? What would you do?

When you installed the GFCI breaker, did you move the bare neutral SE conductor to the neutral terminal on the breaker?

Also, looks like you have two conductors going into a single port on a 2 port Polaris-style connector. That's not proper, you need to get a 3 port Polaris style connector.

And as to a grounding strap, when the oven comes with a 4-wire whip like you have, that doesn't apply. The grounding is determined by how you connect those 4 wires.

Cheers, Wayne

 

[Opifex]

Hi Wayne,

Pictured below is the inside of my main panel. The breaker I replaced is circled. As I recall, I connected both hot wires to the GFCI breaker and the pigtail to the neutral bus. I did not touch or modify the neutral SE conductor in any way (as you can see in the pic, it terminates on the neutral bus).

Thanks for the tip about the 3-port Polaris. I will order one. But as for my tripping problem.... Any other ideas?

 

[wwhitney]

As I recall, I connected both hot wires to the GFCI breaker and the pigtail to the neutral bus. I did not touch or modify the neutral SE conductor in any way (as you can see in the pic, it terminates on the neutral bus).

That's not going to work, the circuit's neutral conductor has to terminate on the GFCI breaker, because the breaker has to monitor all the circuit conductors. If you don't do this, you get exactly the symptom you are having.

[I guess it would work if the circuit were straight 240V with no load on the neutral circuit conductor, although at that point you'd instead call that conductor an EGC, as discussed earlier in the thread.]

Cheers, Wayne

 

[Opifex]

And as to a grounding strap, when the oven comes with a 4-wire whip like you have, that doesn't apply. The grounding is determined by how you connect those 4 wires.

Hmm, okay, I think I understand you. So my question then is this. The oven installation instructions for a 3-wire system show it as I have it currently wired: the neutral and ground wires from the oven are joined. I presume that is the correct method WITHOUT a GFCI breaker. But there is no alternate installation method, since I do not have a grounding conductor. If I disconnect the ground wire, there will be no return path if there is a ground fault, right? What am I missing?

 

[Opifex]

That's not going to work, the circuit's neutral conductor has to terminate on the GFCI breaker, because the breaker has to monitor all the circuit conductors. If you don't do this, you get exactly the symptom you are having.

[I guess it would work if the circuit were straight 240V with no load on the neutral circuit conductor, although at that point you'd instead call that conductor an EGC, as discussed earlier in the thread.]

Cheers, Wayne

Oh.... So the inspector didn't catch that? Ugh.

 

[wwhitney]

The oven installation instructions for a 3-wire system show it as I have it currently wired: the neutral and ground wires from the oven are joined. I presume that is the correct method WITHOUT a GFCI breaker.

It's correct with or without a GFCI breaker. The oven is using the neutral conductor for bonding it's non-current carrying metal parts, which is usually not allowed, but there is an exception for existing branch circuit installations.

But there is no alternate installation method, since I do not have a grounding conductor. If I disconnect the ground wire, there will be no return path if there is a ground fault, right? What am I missing?

The oven's ground wire should be connected to the branch circuit neutral as you have done.

Cheers, Wayne

 

[Opifex]

Okay, so if that's the problem, does the neutral pigtail on the GFCI breaker still have to be connected to the neutral bus?

I will answer my own question: YES. Lol.

Thanks a million, Wayne!

 

[Opifex]

One last question: It looks like the bare stranded neutral is touching the SE neutral where it comes into the panel. Besides trying to physically separate these wires, how do you recommend that I insulate them and prevent them from coming into contact? Would electrical tape be okay?

 

[wwhitney]

One last question: It looks like the bare stranded neutral is touching the SE neutral where it comes into the panel.

That would be an issue for the GFCI to work properly (it could lead to tripping due to some of the neutral current not passing through the GFCI), but would not otherwise be a big deal.

Besides trying to physically separate these wires, how do you recommend that I insulate them and prevent them from coming into contact? Would electrical tape be okay?

Here's what the 2023 NEC (not yet adopted in OR, I believe) says to do when using an existing SE cable that doesn't not originate in the service panel (a new allowance, that used to be prohibited for continued use):

"The grounded conductor shall be insulated or field covered within the supply enclosure with listed insulating material, such as tape or sleeving to prevent contact of the uninsulated conductor with any normally noncurrent-carrying metal parts."

So shrink tubing would be a good option, and if it were fairly tight fitting, you could skip the shrinking. Or electrical tape is fine.

Cheers, Wayne

 

[Opifex]

Thank you for that citation. Thanks again, Wayne!