Stick men
Always bring helpers
is a self-help site
Cost to operate water heater Figure Volts Amps Watts for water heater How to wire tankless electric
How to install point of use water heater Point of use water heater
Compare 16 electric and 3 gas water heater timers Troubleshoot Rheem tankless Clean sediment out of water heater
9 ways to save with water heater
How to install recirculation system Point of use water heater
How electric water heater works Troubleshoot electric water heater Troubleshoot-gas-water-heater Troubleshoot Bosch tankless Do-it-yourself

Connect electric water heater to generator

Connect any 2-wire voltage to ordinary household water heater, and it will heat water.
120V 277V 208V 230V 240V 250V  3-phase non-balanced etc
Do not rewire inside water heater
Connect either voltage wire to either wire on water heater
Do not exceed 30 amps, 4500 watts
Figure volts amps watts for water heater
Single phase generator feeding 3 phase panel


Do NOT touch wet water heater or water heater that was flooded

Flooded water heater
Connect generator to water heater Ordinary electric water heater can run on any voltage from any direction (excluding volt/amp ratings below amount needed to heat tank of water, for example typical 12 volt battery will not heat tank of water).

Voltages include single-phase, split phase, and 3-phase residential/commercial voltages with either 50 or 60 Hz.

Install line fuse if wattage exceeds 4500 Watts.
30 amp fuse would be required to prevent wires from overheating, and eliminate fire hazard.

This information does NOT apply to energy-smart electric water heater with box on top of heater, or newer energy smart with electronics, or to hybrid water heaters, or heat pump water heaters with delicate electronic circuitry.

Why it works like this:
Ordinary electric water heater thermostats are mechanical bi-metal switches and respond to tank temperature, and are not operated by electricity.
Ordinary generic elecrtic water heater thermostats switch electricity on-off using mechanical bi-metal switch.
Heat elements are simple coil of thermal wire that gets hot when voltage is applied.
The element will get hot when power is applied.
Attach electric water heater to generator

Use 12 gauge wire, or 12 gauge extension cord.

Any voltage will work

With smaller gauge extension cord, do not run for very long.
240 volt water heater works with any voltage/ 120 or 240 etc.
Voltage must be less than rating printed on end of each element.
For example 240 volt element will work fine with 120 volts...
... but 120 volt element connected to 240 volt will burn out element

240Volt 4500 watt heats 21 gallons per hour
240Volt  3500 watt heats 16 gallons per hour
Smaller voltage, smaller watt output = fewer gallons per hour.

Most generators want loads balanced across all outlets.
balanced means each outlet draws same amount of wattage.
Unbalanced loads can affect power generation, and life of product..

If you connect generator to whole house power, then turn main breaker OFF

Assumes 4500 watt element rated for 240V
Element wattage and voltage printed on end of each element
How to identify and replace element
Wattage drops when voltage is reduced
See water heater label showing difference between 208V - 240V
Resistive loads such as light bulbs and elements will burn less hot when voltage is reduced. Examples: ordinary household dimmer for incandescent bulbs, or power brown-out when household voltage is reduced
Formula for 240-to-120V:
.25 x 4500 watts = 1125 watts

Question: Is it OK to use Low Wattage water heater elements for heating water using a generator?

For example, I live in Florida and have a 5500 watt generator.
During hurricane season I would like to replace the two 4500 watt elements in my water heater with two 1500 watt elements.

Answer yes. But ....

Might be easier to connect water heater to 120 volt and leave elements in place
240 volt 4500 watt element heats 21 gallons per hour
Connect 120 volt and elements run cooler... they run at 1/4 wattage or 1125 watt... same 4500 240 volt element, connected to 120 Volt... will produce 1125 watts and heat 5.25 gallons per hour

Elements are resistive load... just like a light bulb
When there is a brown out, or less voltage, then light bulbs dims. Less light when voltage drops. Less heating on element when voltage drops.

My understanding is that it is important to balance loads on generator when using 120 volt on a 240 volt generator. Read generator manual.
So if 120 volt outlet is pulling 1125 watts, then other loads on generator should equal same 1125 watt

Important: If your generator only produces 240 volt, or you do not want to mess with balanced loads... then install 1500 watt elements.

Important: buy elements rated 240 volt 1500 watt.... and that will heat about 7 gallons per hour.
Voltage and wattage is printed on end of each element.
Following link shows a few 1500 watt 240 volt elements.

MOST 1500 watt elements are rated 120 volt... to fit into small under-sink tank
Caution:... If element rated for 1500 watt 120Volt is plugged into 240 volt, the element would run at 4x the wattage or 6000 watts... and in theory it should burn out quickly.
Same if you connect ordinary 120 volt 100 watt light bulb to 240 volts... it will burn very bright for a few moments before burning out.

4500 watt element heating 21 gallons per hour is based on 60 degree rise in temperature...
For example incoming water temperature is 60 degrees F, and themostat is set to 120 degrees... requiring 60 degree rise in temperature.
... except incoming water temperature in florida is about 67-77 degrees F... so if your thermostat is set to 120 degrees, your water heater would heat more than 21 gallons per hour.
30 Amp Generator Transfer Switch Kit

30 Amp Generator Transfer Switch Kit/ 7500 watt

When generator comes on, then transfer switch automatically disconnects power from main breaker.
If generator is connected directly to breaker box during power outage, then power can exitwires leaving house and energize power lines outside.
The live wires can slow repair work by power company.
Can also create danger power on neighbor's wires, which they may think have no power.
So bulbs at neighbors house glow very dimly as if there is still power available.
Always turn off main breakwer when connecting generator to breaker box
30 amp transfer switch at Amazon
50 amp automatic transfer switch at Amazon

Reliance 31406CRK manual/pdf
Reliance transfer switch

TCA series: Reliance transfer switch/ manual operation

Purpose of transfer switch: Keep generator isolated from the utility at all times.
100 amp
Up to 15000 watt generator
Unit is ON when utility power is ON
Unit has two breakers that are interlocked... neither breaker can be ON at same time

Reliance transfer switch/ 100 amp indoor/ at Amazon
Reliance transfer switch/ 60 amp indoor/ at Amazon

Reliance TC series transfer switch manual:
Why ground wire is needed
Generator outlet

Generator outlet box wiring:

4-prong generator outlet wiring: All 4 prongs are locking.
all 4 prongs are rounded
1 prong is rounded with upturn.... this it the ground connection
Prong locared opposite the ground connection is Neutral connection
If there is no neutral wire, then do not comnnect any wire to neutral connection
Other two prongs are for hot wires
3-prong generator outlet wiring: All 4 prongs are locking.
all 3 prongs are rounded
1 prong is rounded with upturn.... this it the ground connection
Other two prongs are for hot wires
There is no neutral connection

Twist lock plug / 30 amp/ at Amazon
Twist lock outlet / 30 amp/ at Amazon
4-prong 30 amp generator outlet
Generator outlet boxes at Amazon
4-prong 30 amp generator outlet/ 7500 watt at Amazon
3-prong 50 amp generator outlet / 12,500 watt at Amazon

Cook and stay warm with charcoal briquettes if you have no power

Heat well house or pumphouse with briquettes
Use metal pan, galvanized bucket.
Set bricks in circle on concrete step stone.

Do NOT use gasoline.
Never use gasoline as accelerant.

Use charcoal ligher fluid.
Use newspaper, cardboard, old book to get fire started.
Use WD40.... as last resort... but ONLY small amount on dry briquetts before fire is added... can of WD40 will explode in face.

Smoke will aggrivate asthma
CO2 will be put into air and can cause death if no ventilation
Be damn careful now.

Electricity leaves power plant What is 3-phase electric: power plant to end user

Gas and electric water heaters Industrial electric at Amazon

Industrial supplies at Amazon

Industrial and scientific Amazon
Intermatic control centers Intermatic control centers:
+ manuals and parts

Including Z-wave
box timers Compare box timers

Control with Z-wave
programmable timer Compare programmable timers

Control water heater with programmable wall timer
Countdown timers Compare countdown timers

Control water heater with countdown timer
Compare power packs

My response might end up in spam folder, check email folders
Site map
Follow newest idea on twitter
Privacy policy