Tankless Water Heaters

[jeeper]

Looking for comments on the power supply for these newer large water heaters. These heaters are approved for use in Canada, and they call for 3 or 4 (depending on capacity) 40 amp power supplies. I have not seen one yet, but I think they are like a large hot tap. They raise questions on the demand load on a service and the wiring method to be used. They would be considered as a 100% load using the actual current draw, say 4 x 32 amps = 128 amps. This would not leave much on a 200 amp house service for the other equipment and square footage. This piece of equipment is approved as one piece, Therefore is one point of disconnection or branch circuit required? see rule 26-746(1) Also under 2-304 no repairs etc can be done unless the complete unit can be disconnected. Not sure if the above rules apply. What about just labelling the unit warning about more then one power supply, will this be enough. I couldn't find the rule about marking when there are two supplies. Sorry about the long post, but I think there should be one point of disconnection on each unit. Install a single breaker to feed a dedicated subpanel then have the 4 breakers go on to feed the unit. Maybe I am just peeing in the wind. As a last note there are hot tubs out there with two supplies and they have to be wired with a single breaker to a dedicated panel. Almost forgot the tankless water heater manufacturer is recommending GFI protection on the ciruits to the heater.

[twh]

I don't think 26-746(1) says that one disconnect is required. 26-746(2)(b) says that if each element has a switch, no main is required. As to 2-304, that doesn't require that the complete equipment must be disconnected by one switch, and as you mention, there is a rule about signs on equipment with more than one source of supply.

I've been watching my language, here. I didn't know peeing was allowed.

<font color="#a62a2a" size="1">[ January 08, 2004 11:02 PM: Message edited by: twh ]</font>