I had a 220v installed and now I see most electric water heaters need 240v can I still use 220 or do I have to replace it with a 240v?

A 220V what, cable or heater? I assume you meant cable.

Doesn't really matter, you are just a little confused. An electric cable is rated for a certain amperage and certain voltage. The size of the wire determines the amperage it can safely carry. The insulation determines the voltage. The way the wires are connect in the breaker panel determines the voltage to the appliance.

The service to the house by the power company determines what voltage you have. At one time, a long time ago, service in the US was 110 and 220 volts. That was a long time ago. Service was later increased to 115 and 230 volts, then to 120 and 240V. So you have 240V service. People just can't seem to drop the "220" description.

All residential cable is rated at 600 volts. The size of the cable would be for 30 amps unless the water heater is at an unusually great distance from the breaker panel.

Most residential water heaters require 30 amps at 240 volts. You have 240 volt service. The cable to the heater should 10/2 with ground. The 10 is the size of the wire in the cable and the 2 is for 2 wires. "With ground" means it has an uninsulated ground wire for equipment grounding purposes. You only need two hot wires for 240V to an appliance because a neutral is not required. The connection at the heater is from hot to hot.

Look at the cable. Assuming Romex cable it should be marked "10/2 with ground 600V"

120V means 120 volts to ground or neutral, 240V means 240 volts between two hots which are in opposite halves of the cycle.

Outstanding answer by Bob. If you look closely I believe the rang is 220/240 volts AC.
Your heater will b e just fine. Good luck, Tom

Seems the assumption is this is located in North America. which is 240 volts.

Some other countries are 220 volts.

Where is this located?

Good point TK, guess I was bitten by the ASSuME bug again.

Have things changed so much since In retired that they now make one heater for 220 and another for 20 more volts at 240.
The heater I've installed were rated 220/240. I've also installed one element 110 volt heaters in mobile homes. So now we have two separate heaters rated 20 volts apart? Bring me up to speed. The only way I learn is from you guys. Regards, Tom

Tom,
I think TK was only pointing out that we don't know where the question came from. Could have come from Argentina which has 220 volt electric service.

Now I am confused. When I test one leg of my voltage I get a 11o reading which adds up to 220 on both legs. And I live in Florida. Once more, do they make none heater at 220 and another at 240 or are they still rated at 220/240?Regards, Tom

Power companies are allowed to vary the voltage to meet demand. In Florida you probably get a lower voltage during the summer when all the air conditioners are running. In the winter you probably get a higher than 120 voltage. Appliances are built to tolerate these variances.

Sort of like reducing the water pressure so you don't suck the lake dry filling you pools.

That still doesn't answer my question: I just want to know. Tom

Not in the US as far as I know.

Means they function satisfactorily in that voltage range.

Nicely explained, Bob. Sorry, cannot rate your answer...

That still doesn't answer my question:
Quote:
Once more, do they make one heater at 220 and another at 240 or are they still rated at 220/240?

I just want to know. Tom

Hi Everyone!

Hkstroud isn't Bob... his name is HAROLD and he is THE one and only "left handed widget maker" that I know :)

Further, they do NOT make a 220 volt and a 240 volt heater. As Harold said, all electric water heaters manufactured in the USA are made to operate in the 220-240 volt RANGE... :)

Mark

ThanksMark!
Isn't that what I said in my first post? Cheers, bTom