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Basic 240 & 120 volt water heater circuits


Test for breaks in wire/ Test for voltage
Most appliance require 80% rated voltage to function correctly
Multimeters at Amazon
Electric testers at Amazon
How to test and replace element
How to test thermocouple
Element tests for 120 volts
How to test wire
Safety when testing wires:
Never touch wet or previously flooded appliance.
Never stand on wet surface when working on electric.
Never stand on bare soil, put down dry boards.
Tape tester leads to wood sticks to keep hands away from power.
Use non-contact voltage tester before touching wires.
Never touch or lean into any made of metal.
Remove metal objects from pockets.
Do not use oxygen or fuel accelerants in same room as electrical repairs

Basic house wiring

Non-contact voltage tester

Test for power without touching connectors
NEVER assume power is OFF
Non-contact voltage tester Amazon
Electric testers at Amazon
How to test electric power is off
wire connector assortment

Twist-on wire connector assortments

Do not reuse old connectors
Connector assortment at Amazon
Connector assortment at Amazon
How to select and install twist-on wire connectors
Weatherproof wire connector

Weatherproof wire connector

Connector cavity is full of silicone
Built-in cover keeps silicone in place
Protect from water, dust etc
Buy from my affiliate links
Weatherproof size 14 to 6 Amazon
Weatherproof size 22 to 8 Amazon

How to select and install connectors
Wire connector wrench
Wrench to apply wire connectors
Tighten connector

Wire connector blaster
Twist connector wrenches at Amazon

How to twist wire
How to select and install twist-on wire connectors

Blue for 16-14 wire
Yellow for 12-10 wire

How to install terminals


Terminal kit
Blue for 16-14 wire
Yellow for 12-10 wire
Push on wire connectors

Push-on wire connectors in place of twist-on connectors

Push on wire connectors Amazon
Red 3P connector for 10-14 gauge wire
Lever connectors for stranded wire at Amazon
remove cable staple
End cutting nippers at Amazon

linesman pliers
When removing insulation from wire, do NOT score or put cuts on surface of copper wire. Doing so increases resistances on wire and creates weak point.
Buy tools:
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Linesman pliers
Utility knife at Amazon
End cutting nippers at Amazon

Use solid copper wire
Fire inside timer caused by stranded wire
Keep enclosure door closed at all times
soldering guns

Timer caught fire
Dia 1) Typical residential water heater: 240 Volt 4500 watt:
Black and White wires are hot > bare copper is ground
240 volt water heater circuit
30 amp 10 gauge wire supports up to 5500 watt non-simultaneous water heater
When using black-and-white wires for 240Volt, add tape to white wire.
This action will tell next electrician that white wire carries power

Breaker box
Meter on water heater
Use Kwh hour meter to record usage of water heater.
This is most accurate way to determine what percentage of bill is going to water heater over a full month. Take only showers for a week see what it costs per shower vrs bath ... observe hot water usage for laundry etc.
To connect meter: Temporarily disconnect wires from top of heater. Install meter on two jumper wires. Use jumpers to temporarily reconnect power to water heater. Cover with tape to secure temporary connection. Add conduit and junction box if meter is to be installed for any length of time.
240 volt pass through Kwh  meter

How many kilowatts to heat water
Water heater causing high electric bill
Dia 2) Typical residential water heater: 240 Volt 3500 watt

240 volt water heater circuit
20 amp 12 gauge wire supports up to 3800 watt non-simultaneous water heater

Read label on side of water heater.

Using 12 gauge wire on 4500 watt water heater can overheat wire and breaker, causing shortened breaker life and possible damage to breaker panel busbar

Using 12 gauge wire on 5500 watt water heater will blow breaker

Figure volts amps watts for water heater
Choose correct wire and breaker size
Water heater is tripping breaker
Dia 3) 3-wire 240 Volt circuit with neutral wire: uncommon
Not typically found in residential water heater circuits
Black and Red wires are hot > bare copper is ground > white is neutral
240 volt water heater circuit 
Larger image

How to wire thermostats
How thermostats work

Dia 4) 120 Volt water heater circuit: for under counter water heater
Typical example of under-counter water heater
Black wire is hot > white wire is neutral > bare copper is ground
120 Volt water heater circuit
Water heater will work on any voltage
Convert 240V water heater to 120V
Connect water heater to generator
color-code household wire
Wire sizes

Wire connectors and how to twist wire
How to install under counter water heater
Convert water heater to 120 volts

Main breaker
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Residential Main panel has 120 and 240 volt circuits.
This is called single-phase electric power. Phasing is determined by the power company transformers.

-Each 120 volt circuit can include up to 12 outlets, and supply power to lights inside a room.
- Generally each 120 volt circuit sends power to one area of home. This is because the wire leaves breaker box and goes to first junction box inside a room. From the junction box, the wire splits off and goes to each individual box, jumping from box to box until the final box is reached. So each box will have 1 black hot wire, 1 white neutral wire, and 1 ground wire that connect back to main breaker box.
- Some circuit breakers are dedicated to 1 specific appliance. For example the kitchen microwave is usually wired to 1 circuit breaker and no other outlets or lights are connected to that breaker. This is because microwave draws so much amperage. That is called dedicated circuit, and dedicated breaker.

- Each 240 volt circuit is usually dedicated to one appliance. For example electric water heater is connected to 1 240 volt breaker. The electric dryer is connected to another 240 volt breaker. The heat/AC is connected to another 240 volt circuit breaker, and so on.
See inside main breaker box
How to replace circuit breaker
How to install subpanel
Figure volts amps watts for electric water heater
Difference between single-phase and 3-phase
Electrical problems
-Heat means electric loss. -Hot breaker: put hand on each breaker to feel if it is warm or hot -Undersized wire and breaker: 4500-5500 watt water heater requires 30 amp breaker and 10 ga wire up to 150 feet away from main breaker box. Use 40 amp and 8 gauge wire over 150 feet.

Figure volts amps watts for water heater
Match breaker and wire size
Stress test breaker panel
How to replace circuit breaker
Water heater causing high electric bill

Electricity from pole to breaker box

How to install Subpanel
Electricity is a wave that oscillates at 60 cycles per second. This is called 60 Hz.which appears on electric device labels.

120 volt is like pedaling a bike with one leg. 240Volt is like pedaling bike with 2 legs.
Commercial 3-phase is like pedaling a bike with 3 legs.

Household power is called single-phase or split phase.
Electricity from power plant to distribution substation
What is 3-phase electric: power plant to end user
The grid is defined by three parts: transmission, distribution and end user. The following links show how it works
Power plant to end user power pole
Power pole to residential breaker box
Power pole to commercial breaker box

How to wire basic home electric
How to wire commercial 3-phase

Why you need ground wire
How to wire 3-phase timer
3-phase water heater


How to wire tankless water heater

Replace circuit breaker

How to twist wire

Leaking water heater

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How to wire off-peak water heater

9 ways to save with water heater
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Icon gas valve

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