Dishwasher and disposal wiring on seperate circuits to one yoke and common neutral

Question

Greetings from unincorporated Texas. Home was built in 2000. We’ve been in it for five years. This little adventure started with a push on RO supply line coming loose one night and soaking everything under the sink (and parts beyond). I’ve got three 20A circuits going to the kitchen island through conduit in slab. All are currently OFF at the sub-panel in the house and verified by meter. No breakers tripped the night of the “flood.” One circuit goes to an under sink 15A GFCI and out to two receptacles on either end of the island. This GFCI tripped in the flood. After drying out I reset it. It will no longer trip at the GFCI or remotely from either connected receptacle. This should be an easy fix by replacing the GFCI.

The other two circuits cause me concern. They go to the dishwasher and disposal. Both circuits originate on 20A GE THQP (half width) breakers. The disposal breaker is at 8A (right side) in the subpanel. The dishwasher breaker is at 19 A (left side) in the subpanel. They end at a single split 15 A receptacle with the top outlet being always hot (dishwasher) and the bottom outlet being switched (disposal). They share a common neutral. Between the breakers and the receptacle, things are strange to me. The two (12/2 w/ground) wires from the panel go into a box under the sink. A 12/3 w/ ground goes to the split receptacle. The three grounds from these wires are twisted and SOLDERED. The three neutrals are likewise twisted and soldered AND covered in electrical tape. The black wire of the 12/3 goes to the top gold screw (always hot) on the receptacle and the red wire goes to the bottom gold screw (switched). The 12/3 going to the disposal switch has the ground and neutral wire cut off in the box, but the black, red, AND GROUND are wired to the switch. The entire system is non-metallic. The wizardry in the box was done without a wire nut in sight. Just solder and electrical tape.

So, I want to fix this! Safety > cost! But I really don’t want to install any nuisances.

1. Should I separate the dishwasher and disposal circuits into two different boxes?
2. For safety, should I put both on GFCI outlets?
3. Shouldn’t the ground for the disposal switch be tied to the other ground in the box?
4. Wouldn’t it make sense to install boxes only fed from the bottom under a sink? Essentially having a drip loop on all the wires.
5. Was soldering and taping allowed by code in 2000? LOL. Maybe there was a wire nut shortage?

Thanks in advance for your thoughts.

Jim

Answer 1

This is a mess

What you have here is the result of someone who doesn't care about the "no loops" rules in NEC 300.3(B) and 310.10(H). If you feel comfortable replacing both runs of 12/3 and undoing the solder joints, you can replace the run from the "magic" box to the outlet with a 12/2/2 cable (dual neutral), and replace the butchered 12/3 for the switch loop while you're at it so that the switch can be grounded properly. (Just nut the white wire off at both ends -- 404.2(C) doesn't require neutrals at switch boxes for switches controlling receptacle loads, but it's nice to have nonetheless.)

You'll also need to replace the split receptacle with a 20A duplex with both tabs broken off and handle-tie the breakers for the two circuits if you do this.

Answer 2

Yeah, pull one of the two circuits off that to a new separate box (because it simplifies or enhances the safety of maintenance, even if it's not STRICTLY required to handle-tie two circuits in one box if not on the same yoke, and they are not arranged for a handle-tie.)

If the required plug in reaches the new box, just put your 20A GFCI there, and your other 20A GFCI either in the old junction box or the old receptacle box, as convenient.

You can certainly rearrange the wiring to be more water resistant as you see fit - code is fairly silent on that (i.e. they consider it not a wet location, which is true MOST of the time.)

Yes, the switch box ground should be connected to the other grounds.