Two water heaters....

[mrcaptainbob]

The basement water heater supplies the first floor bath and kitchen. The second floor water heater supplies the second floor bath and laundry. Can they both be wired to the same 30A breaker? I know I have to have an on/off switch within sight of the second floor one. The basement one is only twenty feet from the breaker panel.

[HayZee518]

water heaters

who said you have to have an in sight disconnect?
what is the wattage of both heaters? upper and lower.
is this a two family house or single?
the total sequential load will determine the breaker size.
4500 watts divided by 240 equals 18.75 amps.

[pushkins]

No disconnect in sight is required for any household water heater. I doubt you can wire them sequentially regardless of load.

[HayZee518]

quote from electrical construction

For appliances rated over 300VA or 1/8 hp, a switch or circuit breaker located within sight from the appliance can serve as the appliance disconnecting means. If the switch or circuit breaker is capable of being locked in the open position, it doesn't need to be within sight. The provision for locking or adding a lock to the disconnecting means must be on the switch or circuit breaker and remain in place with or without the lock installed. A portable locking means doesn't meet the "locked in the open position" requirement [422.31(B)]. "Within sight" is defined as being visible and located not more than 50 ft from one to the other [Art. 100].

[mrcaptainbob]

It's a single family residence. For now they're both wired to a 30A 240V breaker. It's been about three days now with no issues of the breaker being over loaded. As for the 'visible shut off' question...I remember reading that a few decades back. A shut off must be visible from the water heater. As an aside...am I correct in thinking that a double 30A breaker means each leg is good to 30 amps?

[pushkins]

yes you are correct

[HayZee518]

water heaters

then explain to me this:
two water heaters, two elements, each 4500 watts, sequential operation. neither element will operate at the same time.
but you have two separate heaters with the same element complement.
4500 divided by 240 volts = 18.75 amps.
18.75 times 2 = 37.5 amps, more than a double 30 can carry.
you are still gonna have 37.50 IF they both decide to kick in at the same time!
tell me what the wattage is for each individual element.
1500? 3000? 4500?

[pushkins]

That's why a single pole 30 amp won't work (nor is allowed) for two heaters in sequence, there is a possibility/probability that both heaters would be heating at the same time. Therefore separate breakers.

[HayZee518]

water heat & breaker

nobody mentioned a single pole breaker.
all water heaters except the single element 120 volt units use a two pole breaker. mine uses a two pole 20.
its a 42 gallon sequentially wired.

[pushkins]

Ooppps ya right I misread, capt. did say 240 V

[mrcaptainbob]

Well, it's been a while now and it's working quite well. I will check the t'stats wattage tomorrow and report back.

[HayZee518]

other than a single apartment water heater especially wired for 120 volt operation I have never seen a water heater wired on a single breaker, 20 or 30 amp to neutral.
all water heaters are 240 volt across them or 120 volt from each leg to the neutral.
they make use of the different polarities and any given instant between them - 120 degrees apart. if it were three phase then you'd have a third leg also 120 degrees from the last cycle.