Tankless Water Heaters in older condo building

[Gord Stevenson]

Hi everyone, I am looking for electrical advice. I am on the HOA board for a resort in Mexico that was built in 2000. There is a small electrical service in each condo, that I would guess has less than 100 Amps. Wiring is original, and to Mexico standards, not US standards. I.e. not the best.

A couple of condo owners have decided that they are not happy with the temperature or reliability of the "hot" water supply and are looking at installing electric tankless water heaters in their condos.  There is no gas service, so it would have to be electric.

One owner is considering an EcoSmart 18.  The web site says it's for condos/apartments; it is listed at 1800 watts.  The specs say 75 A draw; 2 x 40A breakers; and 2 x 8 AG wires.  

What do you think?  To be determined, but let's assume there is enough space in the electrical service box for the 2 x 40A breakers.  How safe is this from an electrical perspective?  Is there a risk of fire?  Is there a risk of affecting other condos' electrical supply?

Thanks!