I replaced 28 gallon water heater: E1F30LD035V, with a tankless: https://a.co/d/1HokO6G. The tank was hooked up to 30 double pole breaker.breaker panel. I thought that was good enough for the tankless, but it stops after a minute or two. After reading some tankless Q&A, it seems the tankless needs a 60 amp double pole breaker. Can I replace the 30 amp double with 60 double? The wires seemed thick, but I don't even know how to check them. The wires are blue, green, and green. Blue is the hot wire,I don't know if that tells the size or not. Thank you.

  • The wires are blue, green, and green. Blue is the hot wire,I don't know if that tells the size or not.
    – Meg
    Commented Jan 14, 2023 at 16:01

3 Answers 3


You will have to replace the wires from the panel to the heater too. A 30 amp breaker probably has #10 AWG connected to it which is only good for 30 amps. Your new heater will require 54 amps which needs #6 AWG wire and a 60 amp breaker. The wire sizes are printed on the wires. If you just change the breaker, you will surely burn stuff up, like your house. You should get some outside help on this

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    The colors do not give a clue to the size. I highly doubt you have anything but #10 AWG in that run. The labeling on the wire is all you really have. You could nip a small piece off the run and take it to your electrical supply store for identification. The diameter of #10 is 0.1019" if you have micrometer.
    – JACK
    Commented Jan 14, 2023 at 17:21
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    @Meg I STRONGLY second JACK's suggestion to get a professional to help you with this. Tankless water heaters take a LOT of power for a short time as they are trying to heat water "on the run" even though most of the time they are using nothing. The wiring, breaker, and unit service all have to be able to handle that super-high operating current flow safely. There are lots of ways here to damage your unit or even a person because of inexperience.
    – Armand
    Commented Jan 14, 2023 at 18:45
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    @Armand COMPLETELY support your comment. I answered with a similar sentiment below. These on-demand electric WHs are energy hogs. We can barely keep the lights on now as a society, what happens when the greenie weenies want everything electric? EV charging, electric stoves , electric heat, no gas cooking or heating? Hopefully sanity will kick in and we'll take a more balanced approach. Commented Jan 14, 2023 at 19:02
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    @GeorgeAnderson There are counties, states that can't keep the lights on now with just normal loading. I've had many calls with people tripping their main breaker when their tankless WH kicked in. In some cases, I've disconnected an element for them.
    – JACK
    Commented Jan 14, 2023 at 19:33
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    I'm not a big fan of tankless WH, they are oversold as energy saving devices, but they are not. Esp not a fan of electric on-demand WHs just way too much concentrated power consumption. I'm also beginning to not be a fan of gas on demand WHs, My son's new build had a fancy multi head shower and a plumber friend of my did a walk thru and he said, there's no way a single on demand gas WH could service that, so he had to install a 2ND on-demand WH. Tank type WHs aren't bad, new ones are well insulated and have the hot water ready right now. Commented Jan 14, 2023 at 20:23

Only if you also replace the wires/cable.

The wire gauge for 30 amps is 10 gauge. 60 amps will burn up that size and can start a fire.

Will need at least 6 gauge wire for 60 amps(per maker directions). Can use larger gauge if you use aluminum wire which is safe at those sizes and cheaper.

Might be a good idea to do a load calculation on your panel to make sure you can have enough power to run the tankless heater. Seeing your panel, a load calculation will be necessary.

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    Note that if you have to run new wire anyway, it's probably easier to just put in a new appropriately sized breaker and leave the old one for later reuse.
    – keshlam
    Commented Jan 14, 2023 at 13:47
  • @keshlam Panel shown in the link seems to only have one free space, and is quite small 12 space.
    – crip659
    Commented Jan 14, 2023 at 13:53
  • It's for a very small 1 bedroom condo.
    – Meg
    Commented Jan 14, 2023 at 16:00
  • I took out the garbage disposal, so I'm not using that breaker any more.
    – Meg
    Commented Jan 14, 2023 at 16:13
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    @Meg It is possible you will not have enough power for a tankless heater. A small condo might just have have about 60 amps for the whole place(yours bedroom apartment). Talk to the condo's maintenance people to find out.
    – crip659
    Commented Jan 14, 2023 at 16:20

So you didn't check the power requirements of the electric tankless water heater and now you're feeling the effects of that. To answer: NO NO & NO, you can't just upsize a breaker because it's doing it's job. Breakers are there to protect installed wiring. Electric tankless WHs are electricity hogs. I really disapprove of them due to their very high amperage requirements and limited flow rate.

At this point, if you wish to keep it, is to upgrade the wiring to it, which could be expensive. It may be less expensive to get another tank type WH and put the tankless WH on Craigs list.

This answer may come across as opinion based, but it's not. When you have a tank type WH you have a lot of stored energy in the hot water in it. A typical tank type water heater with typical 4,500 watt elements (which only one is on at a time) draws just under 19 amps. Yes, it heats water more slowly, but it's stored and ready for immediate use.

Next: An upgrade of the wiring and breaker needed for the electric on demand may not have enough capacity in your main panel/electrical service. An electrician will be needed to determine that. If a panel / service upgrade is also required, that's when it gets REALLY EXPENSIVE. If so, I'd recommend just getting another tank style WH. Some people here argue that they aren't energy efficient, but the new ones are very well insulated and are just fine. IMHO

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