Electric Water Heater max Kw Rating

[Resercher]

For Residential Electric Water Heaters, is there a maximum Kw rating for for the different capacities?
ie
6 USGal Max Kw = 1.5
12 USGal Max Kw = ?
20 USGal Max Kw = ?
30 USGal Max Kw = ?
40 USGal Max Kw = ?
120 USGal Max Kw = ?

 

[kbs]

Researcher

I have never seen anything other than the manufacturer's max rating. I know of no code speaking directly to kw:capacity. I believe you are more restricted by size of conductor and circuit serving the water heater. One of the suppliers I checked sells from a 6gal-3kw to a 50gal-60kw.
Please let us know if you find any code speaking to this.

 

[ChrisConley]

What about 'instantaneous' water heaters, or point-of-use water boosters?

They will have high kW ratings and no storage, so my guess is that there wouldn't be a code restriction.