Wire & breaker size for water heater

[kwired]

Internet searches can just give you the result of what it finds on the internet. There is more wrong information on the internet than correct information. YouTube has the same problem.

Facebook supposed "electrician pages" are horrible for bad information.

 

[kwired]

Well if that is the unit I wouldn't consider it to be a continuous (more than three hours) load.

OP mentioned his is 120 gallon unit, so probably not the one in post 18.

 

[Jpflex]

The bold is the way I read it but after reading it again maybe I read it incorrectly. Maybe jbflex will come back and clarify.

Yes hypothetically it’s 3,000 watts running on 120 volt supply. If taking the journeyman’s test i wanted to be sure my answer was correct but when i check online my answer doesnt match

 

[Jpflex]

Well if that is the unit I wouldn't consider it to be a continuous (more than three hours) load.

Doesn’t NEC code consider water heaters 120 gallons or less as continuous?

 

[kwired]

Doesn’t NEC code consider water heaters 120 gallons or less as continuous?

422.13 is titled "Storage-type water heaters" and is where this 120 gallon or less is mentioned to be considered continuous load.

The one in post 18 would typically be an on demand or instantaneous type water heater and would not be required to be considered as a continuous load.

 

[Jpflex]

Facebook supposed "electrician pages" are horrible for bad information.

I generally didn’t have problems with online info in the past. Most info especially from well written online educational articles have been spot on in my past experience.

I’m starting to see flaws in google and Wikipedia now however. Both Wikipedia and google are politically biased and partial without giving both sides of an argument. It’s now propaganda and brainwashing for one political side. For example, if you google or search Wikipedia for Donald trump you will get a biased biography with opinion replacing facts. No longer do readers get both sides of a debate before concluding their stance

 

[Jpflex]

422.13 is titled "Storage-type water heaters" and is where this 120 gallon or less is mentioned to be considered continuous load.

The one in post 18 would typically be an on demand or instantaneous type water heater and would not be required to be considered as a continuous load.

Storage water heater = a water heater which stores water, by reading NEC the way it’s wrote I wouldn’t think this didn’t apply to all

 

[infinity]

Storage water heater = a water heater which stores water, by reading NEC the way it’s wrote I wouldn’t think this didn’t apply to all

Instantaneous water heaters (also called tankless) do not store water and are not storage type water heaters.

 

[kwired]

Instantaneous water heaters (also called tankless) do not store water and are not storage type water heaters.

I guess the way to describe it is they don't store water that is heated and ready for use at desired temp.

Yes they store some water in the heating chamber when not in use but are only intended to heat water when there is demand for hot water and not to preheat/store hot water.

 

[infinity]

I guess the way to describe it is they don't store water that is heated and ready for use at desired temp.

Yes they store some water in the heating chamber when not in use but are only intended to heat water when there is demand for hot water and not to preheat/store hot water.

Storage type means that they store the hot water and they heat the water even when there is no hot water in use.

 

[kwired]

Storage type means that they store the hot water and they heat the water even when there is no hot water in use.

potato patato

 

[LarryFine]

I guess the way to describe it is they don't store water that is heated and ready for use at desired temp.

Yes they store some water in the heating chamber when not in use but are only intended to heat water when there is demand for hot water and not to preheat/store hot water.

They obviously can't have zero volume, but the heating chambers can hardly be called storage.

 

[infinity]

They obviously can't have zero volume, but the heating chambers can hardly be called storage.

I agree, do we really need to debate what a storage type hot water heater is.

 

[LarryFine]

I agree, do we really need to debate what a storage type hot water heater is.

I hope not.

 

[Jpflex]

Instantaneous water heaters (also called tankless) do not store water and are not storage type water heaters.

I guess the way to describe it is they don't store water that is heated and ready for use at desired temp.

Yes they store some water in the heating chamber when not in use but are only intended to heat water when there is demand for hot water and not to preheat/store hot water.

These are the more modern smaller water heaters that are installed in modern homes that are replacing older large tank water heaters?

The code described water heaters 120 gallons or less being considered a continuous load and so the 3000 watt 120 volt standard water tank heater and all of this type is what I was referring to. In these cases we use 125% ampacity?

 

[Jpflex]

They obviously can't have zero volume, but the heating chambers can hardly be called storage.

Yes I wasn’t thinking of these smaller modern water heaters when describing tank storage water heaters

 

[tortuga]

3000 watt 120 volt standard water tank heater

Just a nit pick but I have never seen such a waterhetater and doubt they even make them even if someone manufactured one I would never consider it standard to have such a large 120V load.
I'd say 'standard' for a residential / light commercial storage type resistance electric water heater the would be 50 gallon 4500W 240V, or 80 Gallon 5500W 240V, and yes that would be a continuous load, 10AWG wire 25A breaker and 10 AWG 30A breaker respectively.

 

[kwired]

Just a nit pick but I have never seen such a waterhetater and doubt they even make them even if someone manufactured one I would never consider it standard to have such a large 120V load.
I'd say 'standard' for a residential / light commercial storage type resistance electric water heater the would be 50 gallon 4500W 240V, or 80 Gallon 5500W 240V, and yes that would be a continuous load, 10AWG wire 25A breaker and 10 AWG 30A breaker respectively.

They do make 1500 watt 120 volt elements though and I suppose could be possible to have a unit that is capable of running both upper and lower element at same time. Probably not common factory configuration though.

A place I am working on has a WH on site though not plumbed or wired yet. It is 80 gallon tank, can't recall exact watt rating but it is @ 277 volts and both upper and lower elements operate independent of one another, so both can be on at same time. However it will be connected @ 240 volts. Converting from 277 volts, again can't recall exact watt rating but do recall it will need a 50 amp circuit @ 240 volts, so it is like 9600 watts or a little less.

I wasn't convinced this is the way to go, but that's what the plumber thought we should use. I think he will be putting in a circulating pump as well

If it were my place I would have put typical 4500 watt in the basement where this one is going, (maybe still 80 gallon) and another 4500 watt in mechanical room that is on the second story. Still looking at similar overall capacity but putting some of it closer to point of use and possibly can eliminate the circulating pump.

 

[retirede]

Rheem makes a 20 gallon with a 2KW, 120V element. I have one in my pool house.
The continuous load factor puts the required circuit size just over 20A. In real life, the thing would operate perfectly fine on a 20A circuit.

 

[kwired]

Rheem makes a 20 gallon with a 2KW, 120V element. I have one in my pool house.
The continuous load factor puts the required circuit size just over 20A. In real life, the thing would operate perfectly fine on a 20A circuit.

Think I have run into one like that before.