Tankless water heater wiring very weird!

[Sierrasparky]

Have you folks ever wired a tankles electric water heater.
I just looked at one that seems quite different. It has three elements and all three elements are wired to one terminal block. The unit is rated at 100 amps and requires 3-2p 40's or 2 -2p 60's.
Are you suppose to handle tie all 3 breakers together. Is this legit?
Most if not all the ones I have seen have a terminal block for each element and a sperate breaker for each. How does this even trip in a fault?
Very weird!

 

[Dennis Alwon]

I would set a 125 amp disconnect with the individual branch circuits from the panel. Not sure you need a main and I don't believe you need to tie them together- not sure how you could do that. A main breaker would cover all doubts- just don't think it is necessary. I have seen furnaces fed with 2 circuits.

 

[defears]

Is it listed? Made for another country?

 

[Volta]

Thinking of 210.7, no one will call it "equipment on the same yoke". I sure wouldn't call it a device.

Should be ok.

 

[ceb58]

The only total elect. one I did took 3 DP 40's. Was not an issue running on three breakers.

 

[chris kennedy]

The only total elect. one I did took 3 DP 40's. Was not an issue running on three breakers.

Did it have a "Warning, more than one means of disconnect" on it or in it?

 

[infinity]

Do you have a make and model number for this unit? 24,000 watts to heat water, sounds awfully expense to operate.

 

[Volta]

Did it have a "Warning, more than one means of disconnect" on it or in it?

I was looking for something that would require that. What section?

409.110(3) is the closest I can find.

 

[Volta]

I guess 422.30 is closer, but not quite requiring that text.

Good idea, for sure, though.

 

[Dennis Alwon]

Do you have a make and model number for this unit? 24,000 watts to heat water, sounds awfully expense to operate.

We did a preschool and they had 2 small 120v water heaters. The health dept made us install a 24kw or 27kw heater( can't remember)---unfotunately they didn't have 3 phase at the site.

 

[chris kennedy]

I was looking for something that would require that. What section?

Oh, I wasn't implying it was NEC required, just something I see more often as of late. (NEMA thing?)

 

[Sierrasparky]

The Man is Hubble ( I doubt the wire device Co) and the model is 240-3. I just don't see how you can tie all the feeders together in parallel and be legit.
This product is made for US and Canada.
Yes and this sucker requires its own service and substation when it's running. It will probably spin the platter of a old dial meter right out of the glass.

 

[infinity]

The Man is Hubble ( I doubt the wire device Co) and the model is 240-3. I just don't see how you can tie all the feeders together in parallel and be legit.
This product is made for US and Canada.
Yes and this sucker requires its own service and substation when it's running. It will probably spin the platter of a old dial meter right out of the glass.


View attachment 5828

I don't see how that unit could be wired up with anything but a single branch circuit.

 

[Little Bill]

I have a customer that has one. It was already in place when they bought the home. It was wired with one 60 but could be two 40s. She liked the idea of the tankless heater and doesn't really have any good place to put a tanked heater. She wanted me to check on putting in a larger one. I checked on it knowing going in it was going to require a lot of power. I believe the next size up was going to require two 60A or one 100A. When I told her I would have to upsize her service she changed her mind quickly. She said they have learned how to use it, not easy with 5 in the family, especially if more than 1 person is taking a shower at the same time. They have to play with the water flow to get it comfortable to use. I also told her the reviews I read on them. Not one of the electric ones, other than a small point of use one, had a good review, and that's not even taking the power consumption into account. I believe the gas operated tankless models are better but quite expensive to start with.
Back to the original question, yes it is supposed to be wired that way, going from the one I saw and looking up others for my customer.

 

[Volta]

I don't see how that unit could be wired up with anything but a single branch circuit.

Yeah, I agree. Maybe the picture provided is for a single circuit type? I certainly would be easy for a manufacturer to design such that multiple elements each can be served by its own circuit, but the various blocks could be fed in parallel when desired.

But if the unit has only a single set of blocks, it seems doubtful that that particular unit would be designed for multiple branch circuits.

 

[lefty]

went to hubbles website

went to hubbles website

It appears by the manufacture recommendations that you can wire it in three different ways. I believe I would use the 2P 100 amp. That way you would have one disconnect for servicing. I've copied and pasted the info and a link where I got the info.
Whole House Water Heater 240-3 Specifications

* Note: Minimum 200 amp service to home required
Dimensions 17" x 16.2" x 3.6"
Weight 20Lbs
Materials Copper Exchanger, Stainless Steel Casing
Pipe Fittings 3/4" Quick-Connect Fittings (Press Fit)
Voltage 240 Volts
Max. Amps 100 AMPS at 240v
(2x60 or 3x40 or 1x100 Amp Double Pole Circuit Breakers Required):blink:
KW / Elements 24 KW / 3 element
Frequency 50/60 HZ
Energy Efficiency 98%
Activation Flow Rate 0.25 GPM
Operating Range 5-150 PSI
Protection Thermal
Warranty 5 years heating chamber
3 years electrical components:
http://www.buytankless.com/store/pc/viewPrd.asp?idcategory=9&idproduct=9

 

[Little Bill]

Ask them how they like their power bill after using it for a while. Better yet, check out the reviews and show them that. If I were going to need one that big I would go with gas.

 

[Dennis Alwon]

It looks to me that the 24kw is 3 phase. The one I did was 3 phase but it could be wired single phase by moving a few wires. There were also fuses in the unit so that no setup had more than a 30 amp on the fuses.

 

[Sierrasparky]

It looks to me that the 24kw is 3 phase. The one I did was 3 phase but it could be wired single phase by moving a few wires. There were also fuses in the unit so that no setup had more than a 30 amp on the fuses.

Nope that 24kw is a single phase. If you heat your water with electric and take showers just as long as before you will save on electric. You are not heating your water all day long.

Technical Specificationsimensions: 17? x 16? x 3?Weight: 23 lbs.kW / Elements: 24 kW / 3 elementsMax. Amps: 100 A @ 240 VCustomer Double-PoleCircuit Breaker / FusedDisconnect Required:1 x 110A or2 x 60A or​

3 x 40A

 

[hillbilly1]

I havn't installed an electric one in a long time, the gas ones are far more superior. The electric ones restrict the water flow so much that most people take them back out. The ones I've installed usually had 2-40 amp circuits that feed two separate heating elements, or had two or more separate units plumbed in series. My sister was going to put one in a couple of weeks ago, but when I told her about the water flow and the fact we would have to double the size of her service, she decided against it!