Different idea for circuit shortage

[RAM]

I have wanted to install one of those small (2.5 gallon) water heaters under the kitchen sink. It takes forever for hot water to get through about 30' of pipe, as well as wasting water and the gas to heat it. Problem was I didn't have a spare circuit for the heater.
What I did was replace the garbage disposal switch with a 3 way switch (which is just a single pole double throw switch). Then I wired the heater to the opposite side of the 3 way switch from the garbage disposal. So now the water heater can be on except for the few seconds a day the garbage disposal is running and I didn't have to figure out how to get another circuit up to the kitchen sink area.

[S-F]

Sounds like that might be a code violation but I'm not sure. There really isn't any wiring in the vacinity you can tap into for your heater? And isn't it a good idea to have a 220v heater any way? Because you pay for the wattage not the voltage.

[randy]

Sounds like that might be a code violation but I'm not sure. There really isn't any wiring in the vacinity you can tap into for your heater? And isn't it a good idea to have a 220v heater any way? Because you pay for the wattage not the voltage.

I don't know about the code violation, but it does not cost less to heat water with 240 volts versus 120 volts. Yes you are paying for the wattage, but wattage is what does the work. A 240 volt water heater at 10 amps, consumes the same wattage as a 120 volt heater at 20 amps and they would both put an identical number of BTUs into the water. The only advantage given by 240 is that it could deliver more wattage at a given current.

[Uncle Michael]

Sounds like that might be a code violation but I'm not sure.

That depends on the locality. In many places the homeowner can do almost anything, but it could be of interest to the insurance company or to a potential buyer down the road. Nonetheless, it's a pretty clever solution, and it's hard for me to see a potential hazard as long as the circuit can handle the load.

Another option is to install something like this under the sink. I have one in the master bath. I ignore its internal timer and use an X10 appliance module to supply power when appropriate. It pumps water from hot to cold until the water temperature is about 60 degrees, then shuts off until it senses the water has cooled again. When we turn on the hot water, even first thing in the morning, it is warm immediately and hot quickly. Without it, it takes several minutes for the shower to become bearable.

[Digger1]

I don't know if it violates the code but I cant think of how it would.

Just because something meets code does not mean its safe and just because something does not meet code does not mean its unsafe. The code is a guide for the Authority Having Jurisdiction and its not necessarily written in stone. Common sense and physics etc have to prevail. Or in some cases a few bucks under the table (a joke but it does happen).

I give it an A for using what is available to get it done.

[Pete]

Here I added circuits to the kitchen circuits which was a PITA because it was all conduit to boxes. I did this by accident on one circuit wiring up a new circuit for an adjacent room. Really nobody would see something like this unless removing the dishwasher (IE: we have now replaced ours twice in 10 years - old home had one for almost 30 years). Conduit run up though went up to two 4X4 boxes with single outlet mud plates on them. I replaced these with double sized metal mudplates for combination switches (and UPB lighting switches).

Here I found electric (boxes) behind the dishwasher and under the sink. For whatever reason a conduit shortcut was done behind the dishwasher instead of using the cavity into the basement and up another wall. I accidentally drilled through conduit from the basement with live wires run across a span of maybe 14" on the wood floor behind the dishwasher. (be safe - please always shut off the breakers when playing with HV electric). It was low on the WAF as it took out the dishwasher and garbage disposal unit fusing / melting the wires in the conduit (discarded that run but had to redo it all). There is one breaker today just for the dishwasher / garbage disposal. Running another circuit for a water heater (after now knowing the runs) would be easy using the conduit. (its like a 40 foot conduit run to the fuse panel).

Personally here while it's working I would keep the circuits and switches separate for this type of endeavor; but that is me and it's a real PITA to run new circuits here. (fishing new wires in existing conduit runs). Many many years ago in very first house owned and installing a new ceiling fan / lamp in dining room doing the electric noticed the disconnect affected that whole side of the house (kitchen and bathroom and part of the living room).

[NeverDie]

Leaving aside the dedicated circuit requirement, which the 3-way switch possibly dances around, it's still worth noting that ampacity calculations can be tricky. A large array of factors can figure into it, including maximum possible temperatures of the space the wiring is running through, as well as the length of the wire run and the insulation quality and temperature rating. Also, it's worth noting that a water heater would be a continuous load, whereas a GD would be non-continuous, and that would affect the ampacity calculation. I think most people, even technical people, are unaware of how involved ampacity calculations can get. I know I was. That said, the NEC does spell it out in detail if you ever want to look up their version of it.

[randy]

Leaving aside the dedicated circuit requirement, which the 3-way switch possibly dances around, it's still worth noting that ampacity calculations can be tricky. A large array of factors can figure into it, including maximum possible temperatures of the space the wiring is running through, as well as the length of the wire run and the insulation quality and temperature rating. Also, it's worth noting that a water heater would be a continuous load, whereas a GD would be non-continuous, and that would affect the ampacity calculation. I think most people, even technical people, are unaware of how involved ampacity calculations can get. I know I was. That said, the NEC does spell it out in detail if you ever want to look up their version of it.

Those are all good points and code notwithstanding I think the OP's solution is safe and reasonable. Since *most* garbage disposers are on dedicated circuits and his water heater likely has a 1500 watt element, it is unlikely he would exceed the capacity of even a 15A 14 gauge run.

Code is an interesting thing as well. I live in a house that, as constructed, had the garbage disposer on a 20A circuit. There is a 15A rated switch controlling the disposer outlet - also a 15A rated device. The way the kitchen is wired (as well as other circuits in the house) they ran 12-3 with ground to that circuit. The red wire hot is the wall outlets on that side of the kitchen, the black is the dedicated run for the disposer. So... 2 20A circuits are sharing a neutral and a ground. In addition, to save wiring, they put a light switch in the disposer switch box for a light over the sink - another 15A switch and now 14 gauge wire from that switch to the light. This is a tract home, with many duplicate floor plans in the neighborhood. They were all built by the same builder, inspected and approved by the same municipality.

Care to add up the number of violations in just that one scenario? This was all built into my house and dozens of others in the late '70s. This is on an outside wall of the house. The only easy solution I could come up with to make me feel a little safer was to replace the two 20A breakers with 15A units. In theory I still could exceed the capacity of the neutral on that circuit if both legs were running at close to their capacities. The disposer is rated at 1/3HP and the light is an LED, so the risk is low. On the other side of the Kitchen the wall outlets and the microwave were wired in the same fashion. I pulled a fresh 12 gauge run to the microwave, eliminating the use of one conductor in the 12-3 on that run.

[Pete]

Yup; here only have not to good of memories living in that space where the dishwasher was under the kitchen counter for what was seemingly hours playing with the electric stuff. (un natural bending of my body while concurrently doing this stuff was no fun).

Well that and hearing if I was done yet behind me (WAF stuff) as I had taken out a daily utilized section of the kitchen. (dishwasher was sitting in the middle of the kitchen disconnected for a period of time).

I do not like that whole mixture of plumbing and electrical stuff and its always mentioned to my wife by me as a 10 minute fix and never is.

[Automated]

Different idea for circuit shortage

Funny stories Pete. Your luck and timing are about like mine. One day projects take three, and every project on our house draws blood at least once.

[RAM]

Those are all good points and code notwithstanding I think the OP's solution is safe and reasonable. Since *most* garbage disposers are on dedicated circuits and his water heater likely has a 1500 watt element, it is unlikely he would exceed the capacity of even a 15A 14 gauge run.

Code is an interesting thing as well. I live in a house that, as constructed, had the garbage disposer on a 20A circuit. There is a 15A rated switch controlling the disposer outlet - also a 15A rated device. The way the kitchen is wired (as well as other circuits in the house) they ran 12-3 with ground to that circuit. The red wire hot is the wall outlets on that side of the kitchen, the black is the dedicated run for the disposer. So... 2 20A circuits are sharing a neutral and a ground. In addition, to save wiring, they put a light switch in the disposer switch box for a light over the sink - another 15A switch and now 14 gauge wire from that switch to the light. This is a tract home, with many duplicate floor plans in the neighborhood. They were all built by the same builder, inspected and approved by the same municipality.

Care to add up the number of violations in just that one scenario? This was all built into my house and dozens of others in the late '70s. This is on an outside wall of the house. The only easy solution I could come up with to make me feel a little safer was to replace the two 20A breakers with 15A units. In theory I still could exceed the capacity of the neutral on that circuit if both legs were running at close to their capacities. The disposer is rated at 1/3HP and the light is an LED, so the risk is low. On the other side of the Kitchen the wall outlets and the microwave were wired in the same fashion. I pulled a fresh 12 gauge run to the microwave, eliminating the use of one conductor in the 12-3 on that run.

I'm pretty well covered as far as having everything in the circuit heavy enough. This circuit was a dedicated 20A circuit for the garbage disposal. Everything is rated for 20A; all the wire is 12ga, the 3 way switch and outlet I installed are rated for 20A, so nothing is undersized at all. If anything is undersized it's the factory cord for the water heater. (FYI, the water heater element is 1250 watts.)

In about the one week since I installed it, I have checked with my Kill-A-Watt meter and calculated that this heater will only be costing a little over $1.00 per month. for electricity. For instant hot water and the savings in wasted water, it is sure worth it to me.

[randy]

In about the one week since I installed it, I have checked with my Kill-A-Watt meter and calculated that this heater will only be costing a little over $1.00 per month. for electricity. For instant hot water and the savings in wasted water, it is sure worth it to me.

And I'll bet that it is far less energy cost than a hot water circulation system. We're fortunate - we live in a small three bedroom ranch w/basement and the kitchen as well as both bathrooms are within no more than 10' (as the pipe flies) of the DHW tank. Otherwise we would probably employ the solution you did.