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Your electrical water heater and also gas tankless water heater require circuit breakers come operate. However, the wrong sizing the the breaker have the right to lead to decreased safety and also potentially damages the water heater. The extr electrical circulation through the breaker put the wires at threat of overheating, leading to a fire, and damaging her water heater. 

The National electric Code outlines guidelines the govern the sizing that circuit breakers and wiring for electrical safety. Follow to the NEC Code, girlfriend should constantly size her circuit breaker in ~ 125% the the load. This means, for safety purposes, that is recommended that you invest in a greater capacity circuit breaker than the electric load of your electric gadgets – in this case, her water heater. Electric water heaters require a dedicated 240-volt dedicated 30-amp circuit and also a 10-2 non-metallic (NM) or MC cable. This way the breaker only powers the water heater and no other appliances. A 30-amp circuit breaker deserve to power every 4500watt water heaters regardless of gallon size.

You are watching: What size breaker for a hot water heater

Occasionally, I’ll check out a 20-amp circuit breaker ~ above a 4500-watt water heater. If this is technically correctly sized, it leaves tiny room for overcurrent and also does not satisfy the NEC 125% fill guideline. The breaker size is identified by the wattage the the heating elements and not the tank size. An ext on that shortly.A water heater v a 4500-watt heating facet requires a 10/2 wire with a 30 amp (240volt) circuit breaker. The 3800-watt heating aspect can be wired with a smaller sized 12/2 wire and a 20 amp circuit breaker.


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Sizing Water Heater Breakers 

The crucial to gaining the best size for a water heater is in understanding how the heater works. Electric water heaters usage anything in between 220 to 250 volts of alternative current. You’ll require a dual circuit breaker that is correctly rated because that the power attract of the water heater. We’re feather at between 20 Amp and also 30 Amp for most electric water heaters. When looking at the sizing native the power requirements, you likewise need to consider the cable gauge size. The amperage drawn by the heater identify the cable gauge size.

Element WattsBreaker size 120vBreaker size 220vWire Gauge150015 amp15 amp14200020 amp15 amp14250030 amp15 amp14300030 amp15 amp123500NA20 amp124000NA25 amp104500NA30 amp105000NA30 amp105500NA40 amp8

How do You calculate Breaker Sizing?

Check her water heater’s wattage and also voltage ratings. A water heater’s wattage and voltage rating come labeling on the sticker ~ above the thermostat panel. Some heaters have this information near the base. While many residential water heater units have 4500-watt capacity, advertisement water heaters have the right to reach 5500 watts.Now, let’s acquire into the mathematics of calculating breaker sizes. 4500/240 = 18.75 amps. 18.75X125% = 23.4375 rounded come 25 amps

If you have a 4500-watt water heater with 240 volts, using the standard division formula friend should end up v 18.75 amperes. However, mental an electrical water heater runs on a consistent load. So readjust 18.75 by 125%, factoring in the a water heater runs a continuous load. Multiply 18.75 amperes through 1.25 to get 23.4375 amperes. When we round off the number, we get 25 amp. You’ll require a 25 or 30 amp circuit breaker. The 30 amp is universally used because the minimum rating that 220 volts exceeds the 25 amp breaker. 4500/220 = 20.45 amps. 20.45 ampsX125% =25.568 rounded to 30 ampsWhy not 20? after all, the IS closer come 18.75. 

Well, 18.75 is only about 94% that the breaker’s amperage. Yet going by the NEC 125% rule, a 20 amp is a risk of regular tripping and could damage the water heater. A 25 amp breaker is sufficient; however, many electricians will certainly install a 30 amp circuit to administer room for electrical fluctuations as outlined above.

What size Circuit Breaker for Gas Tankless Water Heaters?

Gas tankless water heaters use much less power draw and also less voltage than electrical tank water heaters. Usually, it’s around 12 amps and also less 보다 120 volts. Gas tankless water heaters need a minimal quantity of electrical energy to power the electronic ignition system. A gas tankless water heater only needs a 15-amp, 120 volt dedicated single-pole breaker for this purpose.

Should i Have electric Water Heater or Gas Water Heater?

This an option depends on her locality and also the utility prices of her area. However, gas units typically cost more upfront yet price less to run than electrical water heaters. On the brighter side, electric water heaters are an ext energy-efficient than gas water heaters. Gas costs 40% the the price of electricity. Therefore, it would be cheaper to usage gas. However, as soon as you look in ~ time savings end time, electrical water heaters are an ext economical. Getting the appropriate size circuit breaker can get technical. If she looking to make upgrades to accommodate electric, gas, or tankless water heater systems, girlfriend should call a professional. historicsweetsballroom.com is owned and operated by hubert Miles is a participant in the Amazon solutions LLC Associates Program, an affiliate advertising program designed to administer a method for sites come earn heralding fees through advertising and linking to Amazon.com. historicsweetsballroom.com also participates in affiliate program with other affiliate sites. Hubert Miles is compensated for referring traffic and business to these companies.
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Hubert MilesI"ve been conducting residence inspections because that 17 years. I"m a licensed residence Inspector, Certified master Inspector (CMI), and also FHA 203k Consultant. I began historicsweetsballroom.com to aid people better understand the house inspection process and prize questions about homeownership and also home maintenance.

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