Disposal Wiring Puzzle

[mechD]

We recently had counter top replaced and had to move the disposal switch after cutting down a bi-level counter.

After moving a light switch and the disposal switch we were still using the sink (including the disposal with the new switch that was working perfectly fine) and limited surfaces awaiting the counter top installation. We used the disposal with the new switch location for about a week.

Then, with everything out of the way and the disposal protected from the installers (but still with connected wiring), the new counter top with new single bowl sink was installed.

The disposal was mounted on the right side of the sink (where the single drain is) and the DW is now connected to drain into the disposal (it was not draining into the disposal with the old sink).

After mounting the disposal, it now does not turn on. There is no humming, no noise - nothing. The reset switch is not popped and pushing it does not correct the problem. I've reset the breaker (that was never tripped) multiple times - still nothing. A check with a voltmeter indicates there is voltage going into the unit.

I called Insinkerator customer support and the conclusion was that I needed a new unit. The new unit arrived. I installed it - same result. Voltmeter indicated voltage into the unit when the switch is turned on, and no voltage when the switch is off. I have no idea what is going on - any help is much appreciated.

The unit is an Insinkerator Evolution Excel. (The old unit is just over 8 years old).

 

[Stuff]

Guess is that the neutral wire in the cable is broken. Measure voltage between hot and neutral as well as between hot and ground.

 

[Sponsor]

 

[hj]

No way to answer you because we do NOT know how you are measuring the voltage. IF voltage is going into the unit, especially with a new one it HAS to run, unless the reset button has popped out for some reason.

 

[mechD]

Hot to neutral is 34 V AC and hot to ground is 120 V AC as measured on a multimeter. That is at the terminal end of the wiring (in agreement with switch positions).

I reconnected the unit after double-checking with an Allen wrench in the bottom of the unit, but it still isn’t running.

I also opened up the switch and checked all the connections there with a non-contact AC voltage detector. There was power on both sides of the switch (also in agreement with switch position).

You might be right about there being a break in the neutral somewhere (not what I want to hear). I’m going to disconnect the switch and check hot to ground and hot to neutral there. There’s also a couple of kinks in the wire upstream of the unit, but I didn’t want to start cutting and splicing until I had exhausted other options.

 

[Reach4]

You might be right about there being a break in the neutral somewhere (not what I want to hear).

He is right. If you measure the voltage from neutral to ground at the disposal while the switch is on, you will see that.

 

[Cacher_Chick]

Your measurements prove that the neutral is bad. Is your disposal plugged into a receptacle in the base cabinet? The circuit could be wired with the switch at the beginning of the circuit or the switch at the end of the circuit. Determining how the circuit is wired will be useful in determining where the open in the neutral is most likely to be.

 

[WorthFlorida]

Hot to neutral is 34 V AC and hot to ground is 120 V AC as measured on a multimeter.

At the point you made this measurement. Open the white neutral connections completely. With the switch on, the hot wire to the white from the disposal you should read zero volts. From the disposal white wire to the green ground, if you measure 120v’s the neutral is open from here to the power source. If you read zero, it’s open toward the disposal.

I hope this made it clear.

 

[Jadnashua]

WHen everything is working properly, hot to neutral and hot to ground should be identical. Things run when the proper voltage is between hot and neutral...you likely have an issue with the neutral as everyone has indicated. It could be a loose connection, a nicked wire, or broken one that won't support 'normal' current flow. A common problem is a nicked wire when you stripped things...the wire can break at that point much more easily.

 

[mechD]

Yep, that makes sense. I should’ve caught that earlier. I have a few points where I can start trying to pinpoint the trouble spot. Luckily, I know it was working after the demo. The wild card is the counter install.

 

[WorthFlorida]

I made a few bad wire nut connections myself and the most common problem is when twisting wires to accept the wire nut. If one of the wires were twisted before when you tighten the wire nut down, I’ve broken a wire under the nut.

The second usual problem, and I’m suspecting the white wire at the disposal wire nut, is the stranded wire didn’t wrap properly around the solid copper wire (I’m assuming it is direct wire). As you tighten down the nut the stranded wire get pushed down and wraps around the insulation and doesn’t touch the solid copper. Sometimes the wire nut grabs the insulation and holds it together as if everything is good. A wire, BLK or WHT also could have pulled out of the wire nut as you moved the disposal around.