what size wire for 4500 watt water heater

What Size Wire for 4500-watt Water Heater and What Works The Best

Most electric heaters will be 4500-watts or higher. Low power models are not usually a stock item.

You won’t necessarily need to increase the wire size if you are looking for a temporary fix. It would also be odd to use a 10,000W element when you have plans for the near future. One of the original sizes will suffice for now.


What size wire for a 4500-watt water heater?

One of the only reasons to pick 3600-watt elements over 2400 watt elements is if your heater has more than good wires for them. If this is the case, then a 30 amp breaker will cause an unsafe condition. The way it’s geared up now is a 12/2, 20 amp twin breaker. The Rheem tank I have takes 3500 watts.

You can’t cause a fire with 10 wires and a 20 amp breaker. The fire hazard happens when you have 12 wires and a 30 amp breaker.

My water heater will need 65 feet of cable. Are 10 wires enough for a 50 gallon? Rheem seems to be far from the main breaker box. Find out the answer in the next section!

Can 10/2 wire be used for a water heater?

Your breaker size would be 25 when using wire 10/2 when upgrading from a 60 gallon to a 40 gallon.

Then a 20 amp would be okay for 3000 watts? 10/2 should be good for all those scenarios.

Remember to sleeve 10/2 cable as it comes from the wall or from an outlet to connect to your water heater. You can’t have “exposed” non-metallic. This short section of flexible conduit is easy to deal with if you don’t use an EMT conduit.

The previous owner used a 10/2 cable with a 30 amp DP breaker with the 60-gallon 4500w tank.

Can 12/2 wire be used for a water heater?

For your electric water heater to work properly, you’ll need a 30-ampere grounded 240-volt connection. 12/2 wire is rated for just 20-amperes; to power the water heater, you’ll need 12/3 wire.

Even a small 6-gallon, the 1500-watt water heater would require a 12/2 plus ground wire. 12 gauge wire will be limited to 20 amps, and most normal-sized water heaters will expect more current than that.

An electric water heater is typically 220/240 volt which means it has 2 hots, 1 neutral, and 1 ground. Both your red and black are hot leads. With no more knowledge than it appears that you have, I strongly advise that you consider hiring a professional.

A 20-amp water heater requires 12-gauge wire. A 25-amp water heater requires 10-gauge wire.

I recently bought a house, and my inspector showed me a 12 gauge wire connected to a 30 amp breaker. He didn’t know that the breaker was designed for 20 amp use.

The water heater you have is called the Reliance 602. It has a 4500W heating element, which is okay. The wiring at the top is also fine, at 12MV/24AWG.

What’s better: 20A or 30A breaker?

So, is it better to install a 12G wire and a 20A breaker or go back to the 30A breaker??

The National Electrical Code (NEC) requires fixed heating system branch circuits sized for 125% of the connected load. This system also applies to domestic electric water heaters. In your case of a 4500-watt heater, the minimum size for the circuit would be 23.

You need 10 gauge wiring for your heater and either a 25 or 30 amp breaker. Your local codes may be flexible here, but not 30 amp wiring with 12 gauge.

Use a 20 Ampere breaker. You may have nuisance trips on.

It’ll take quite some time to fix the 20A. I want to stick with the safest possible configuration. Remove the 20A breaker and remove the 12 wire! Wire up 10 AWG & connect it with a 30A breaker.

A twenty-ampere circuit breaker on a 12 wire will not be a fire hazard. The max power draw of the water heater is 18.75 amps. I already stated that the installation of WH complied with relevant codes and regulations, including those regarding electricity.

Does 20A work well with 12G wire?

You can have a 20 amp breaker with 12 wires if it’s for a water heater that’s up to 30 gallons in size. If you’re using 4500-watt elements, you’ll need to use at least 14 gauge wire. Now, do you want maximum safety? Is the suggestion always to go with the standard 14 gauge wire?

Neither of these scenarios is ideal, but replacing the 12G wire is not an option at this moment in time. I’ll have to tear apart a goodly portion of the house to replace the wire.

If you are not allowed to use 12, you must use 15 amp. This setting is your standard for 16/3 wire.

If you use a larger breaker, the wire might overheat. Let’s say that your WH is drawing more than 20 amps, and you want to be safe and install an appropriate breaker, but 10 amp will not be enough to handle the demand.

20 amp breaker is what I recommend. It trips if there is too much current so that it won’t catch fire. You’ll want the breaker to trip before the wire does!

Does 30A work well with 12 wires?

The inspector found a 12-gauge wire attached to a 30-amp breaker. A common issue with this configuration is that the wire may overheat and fire before the breaker trips.

Here’s the option:

1. Check for lamps that will fit your tank and provide 5000-5000K light.

2. We beg you to abandon attempts with the element and wire. Next, please do the following: change the breaker with a 20 amp and hope for the best after that;

3.) Leave the 4500-watt elements alone and change BOTH.

I would go with #3!

Typically, a circuit breaker should not have a continuous load exceeding 80% of the rating. It means that in a 20-ampere outlet, only 16 amps would be allowed. The only correct suggestion to fix this problem was to replace the water heater elements with 3500-watt units temporarily.

Some residential areas get a 208 volt single-phase network.

According to this, it should read 3600 watts while still at 240 volts because that’s the measurement of power usage.

Can the wiring to a water heater be extended via a junction box?

The existing wiring to a proposed new water heater will come up about 2-3 feet short. The way it’s currently run, it offers zero slacking to work.

Can some junction box be installed to gain the required length needed?

The wiring runs about 15 feet from the main panel to the existing water heater.

2 thoughts on “What Size Wire for 4500-watt Water Heater and What Works The Best”

  1. A'Journe Spyker

    I’m installing a Bradford White 50-gal. water heater, with two 4500w (240 v) elements. The wiring (in the wall) is done; and that wire is heavier than necessary. I used it because we already had that piece of wire.
    But – what about the short piece (between the wall box and the top of the heater? (which will end up to be no more than 3 feet in length). I’m wondering if # 12 wire will be heavy enough for that; or do I need to use # 10? (I mean – the wiring INSIDE the heater, used to connect the elements is not super-heavy, right?)

    1. To be safe, you can use # 10, even with # 12, typically will be less than 20 amps but a close call. Also it’s not recommended to splice together wires of a different gauge.

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