Does this device exist?

It does cover kludged relays that control line-voltage appliances.

Peter Wieck Melrose Park, PA

Once again I fail to make myself clear. The water heater is for hand washing dishes, not the diswasher. That's why the heater can be off when the dishwasher is running. In my brother's house dishes are washed more by hand than by dishwasher but bioth get used. Eric

Then, even the smallest POU heater will be fine for dishes, as long as the user does not leave it on "BLAST". Keep in mind that the average handwash f or two users, one meal, is about 2.75 gallons (10.5 liters) of water. Moder n dishwashers use, typically, less than a gallon (2.75 liters).

You are over-complicating a rather simple problem.

Peter Wieck Melrose Park, PA

An on-demand system would be perfect for him and take up much less space. Why doesn't your brother want an instant demand heater?

If it's electrical draw that exceeds the wiring, I'd just snake in new wiring and a new breaker and use the on demand heater.

Where I am, the hardware is the same. The installer simply breaks out the connector tab between the 'hots'.

Simple.

Don't hand wash dishes if the dishwasher is going.

I don't see the problem or the need to automate something that can be handled by the grey matter between the ears.

RwP

Actually, I'm not. They tried a small instant hot heater. It did not provide enough hot water. They saw the small water heater I use in my shop and they think it is perfect. It just draws too much current to be used at the same time a dishwasher is heating. Eric

Sheesh! He is not gonna run a new wire. I already said that. It is not an easy task. Power would need to come down from the attic. Eric

The solution is, then, contained in how you stated the problem.

a) A tankless POU water heater uses current only when flowing. b) A dishwasher wants hot water to feed it, but it does not require it to f unction properly. NSF regulations see to that. c) If your brother is able to restrain himself to not running hot water to the sink except when the dishwasher is OFF, just go with a larger tankless device. They come (in the US) up to 18 A at 120 V.

Under your sink, run the tankless heater to a separate dispenser - some eve n come that way. Use the regular hot water line to feed the dishwasher, and the cold line to feed the sink. Note that separate dispenser devices will make water hot enough for tea or instant coffee at one setting, then dial b ack to sub-scalding temperatures for washing use. Handy little things.

Ultron comes to mind as a brand name.

Peter Wieck Melrose Park, PA

Only if it's hard wired, If it plugs in, it's an appliance itself.

Googling "small water heater 120V" I got a bunch of stuff, here's a 6 gallon one.

Is that what you want?

George H.

It's actually smaller, about two gallons. Eric

such demand management is perfectly legal here.

The US has three levels of "management" for electrical (and other) devices:

a) The National Electrical Code (NEC): This regulates hard-wired systems an d switchgear, and how peripheral devices are connected to the system - such as light fixtures and other devices not plugged in. A hard-wired relay wou ld be considered "switchgear" and therefore covered.

b) UL (Underwriters Laboratory) - this is a 'family' of such bodies, of whi ch UL is the most prevalent: UL regulates those devices that connect to the system above, and has to do with (among many other things) grounding, elec trical safety, loading, and so forth. This applies to stand-alone (complete ) devices. Note that such devices are "LISTED", not "approved".

c) UR (Recognized): This applies to individual components within a system - such as a relay in a control, or similar. That part does not stand alone. but may be replaceable. So, if one has a UL device of several parts, one fa ils, then that part *must* be replaced with a UR part to retain the UL list ing.

Why it matters: There is this funny thing called "insurance". And if one ha s property insurance, and reads the fine print, it will refer to things mee ting code and being properly inspected and so forth. It will also refer to 'connected devices' or any number of other words for whatever one has to pl ug into the wall as being "listed".

Should that hand-made relay you are referring to cause a fire and cause dam age such that the property owner makes a claim - and should the insurance i nspector (and there will be one) determine that the cause was this unlisted /unrecognized device - OOPS! Either the Company will not pay, or if it does , it will then immediately cancel the policy. And the property owner will be quite challenged to get insurance in the future at any reasonable cost.

Nothing that was done was "illegal". And Code Violations are not "illegal".

Just stupid. Something you continue not to understand. And the advice you g ive continues to suffer for it.

Peter Wieck Melrose Park, PA

In Ranger, the code works like this: "It ain't blowed up yet has it?" And when it inevitably does: "Aw man, it blowed up. You must'a doned it wrong."

Neutrals can be 1 or 2 sizes smaller, because, you know, no current in Neutral or they would have called it something else.

#8 for a water heater? #10 is cheaper. Same reason #14 works for outlets.

Double breakers with a pin between the handles? Pish tosh, a pair of singles works just fine, and they DON'T have to be next to each other.

Run out of wires? Use the bare one for ground and neutral, then you can use the white one for power.

No ground in the outlet box? No problem tie the neutral and ground screws together.

And yeah, I'm waiting for my neighbor's house to explode.

No, it wouldn't work. Normal relays working with DC coils. You need a very special relay designed for AC coils. Very rare and likely expensive.

Contactors exist for AC and DC coils, maybe they work. You need one with contact type NC i.e. closed for feeding the heater when no current is drawn from the dishwasher. These NC types are not common too.

Wolfgang

Not rare. But certainly expensive, by a factor of 3 to 5. The difference, a t the simplest level, is that the AC-coil relay has two coils (transformer) such that the second is producing current as the first is 'collapsing', th ereby holding the contactor in place instead of "chattering". That is, as stated, the simplest description of a not-simple configuration - hence the cost.

Peter Wieck Melrose Park, PA

description of a not-simple configuration - hence the cost.

BS

They are not rare or is the price that much different.

For example a plug in relay that is almost identical except for the coil voltage and current As listed in a Mouser catalog.

KRPA-11AG-120 $ 22 120 Volt AC coil 10 amp contacts KRPA-11DG-24 $ 16 24 Volt DC coil 10 amp contacts.

That so called second coil is really just a thick piece of copper at the top of the coil. Large AC contactors often have similar pieces of copper on the laminations.

I worked in a plant that had hundreds if not thousands of relays similar to those. Part were AC coils and part were DC coils.

Now solid state 'relays' are often used in switching AC circuits off and on. We used many of those also.

Don't ya just love people who change the invariants of a problem to 'solve' it?

Is there a reason that the hot water heater+tank needs to be under the sink? Would it be possible to mount the heater under the floor under the sink and run a pipe up to the sink? Might allow wiring in a space that is more accessible.