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Water heater element tests for 120 Volts
Use only 600 volt wire.
Lamp cord, extension cords are not rated 600 volt.
Use copper wire only. Aluminum wire is fire risk and should be avoided or installed by professional.

30 amp breaker use 10 gauge /
120-240 volt 30 amp outlet can be installed on 30 amp breaker only/ use 10 gauge wire ... cannot be connected to 15-20-40 amp breaker.

Orange/ #10 gauge wire, with ground ... 30 amp capacity. Safe maximum: 30 x 80% = 24 amps.
Buy:
10-2 gauge/ 30 amp
10-3/ 30 amp
Southwire electric tools
Yellow 12 gauge 20 amp
120 volt 20 amp outlet can be installed on 20 amp breaker, but not 15 amp breaker/ use 12 ga wire.
... cannot be connected to 30-40 amp breaker. 1

Yellow/ #12 gauge wire, with ground ... 20 amp capacity. Safe maximum 16 amps.
Buy:
12-2 gauge/ 20 amp
12-3/ 20 amp

NMB is house wiring
UF is underground
Rolls of stranded wire
HOOK UP Wires
White 14 gauge 15 amp
120 volt 15 amp outlet, AFCI, GFCI, timer, switch etc can be installed on 15 or 20 amp breaker. Never connect 15 gauge wire to 20-30-40 amp breaker.

White/ #14 gauge wire,  with ground ... 15 amp capacity. Safe maximum 12 amps.
Buy:
14-2 gauge/ 15 amp
14-3/ 15 amp

NMB is house wiring
UF is underground
50-60 amp breaker use 6 gauge /
240 volt 50 outlet can be installed on 50 amp breaker only
6-2 wire
Buy:
6-2 wire
Southwire electric tools
NMB is house wiring
UF is underground
40-50 amp breaker use 8 gauge /
240 volt 40 amp outlet can be installed on 40 or 50 amp breaker only
6-2 wire
Buy:
8-2 wire
Southwire electric tools
NMB is house wiring
UF is underground
     
Copper ground wire.
Every device, load, metal enclosure etc must be grounded. Ground wire must be continuous throughout installation, never switched on-off, never used as a Neutral wire.
Generally ... use same size as other wire in circuit
Buy:
12 gauge copper ground wire
Ground wire
Green ground wire
Ground pigtails
Ground rods/ ground clamps at Amazon
armored cable
Non metallic flexible cables must carry ground wire, but do not have hazard of short circuit causing injury from shock.

Armored steel cable can be used as a grounded connection, and will protect wires from damage. Metal can be energized from an insulation failure.

All conduit ...metal, plastic ... flexible and rigid ... must be attached to structure, and attached to enclosures, boxes.
Movement, damage and deterioration are major cause of electrical failure.
Buy:
Non-metallic flexible conduit
Power whip
Armored cable
Southwire armored cable cutter
Pull boxes
Southwire armored cable cutter
Electrical tools must be insulated.
Always best to disconnect power, but insulation failure, lack of proper grounding, grounded neutral, lack of GFCI, out-of-code wiring, generator operating without transfer switch, and other problems still pose a risk to anyone working on electric power ... even when breaker is off.

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Electrician tools kits
KLEIN TOOLS
Tools kits
IRWIN tools
KNIPEX

Telephone cable knife
Low Voltage Mounting Bracket for Telephone
Push on wire connectors

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

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Push on wire connectors Amazon
Red 3P connector for 10-14 gauge wire
Lever connectors for stranded wire at Amazon
HOOK UP Wires

Protect wiring from damage
Use nipper instead of pliers or screwdriver for removing staples (and nails). Do not damage cable or wires inside cable.

-Code says: Cable SHALL BE secured without damage to the outer covering. NEC sec. 336-15
Buy
End cutting nippers at Amazon


Electrically insulated tools
When removing insulation from wire, do NOT score or put cuts on surface of copper wire. Doing so increases resistance and heat on wire and creates possible weak point.
Buy tools:
KLEIN TOOLS
Wire strippers at Amazon
Electric Wire Stripping Machine
Linesman pliers
Utility knife at Amazon
multimeter
Multimeters
Voltage is tested across two separate wires. Ohms or resistance is tested across both ends of same wire. Amperage is tested along one or two points on same wire.
Buy:
Analog multimeter
Multimeters at Amazon
Klein multimeter
Electric testers at Amazon
Clampmeter for testing amp flow on line

GFCI circuit breaker
A GFCI circuit breaker will protect all boxes on circuit.

Circuit must be grounded. Ground wire must be continuous and connected to each piece of equipment.

White wire on circuit breaker must be connected to Neutral busbar inside the breaker panel.

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Push down
single-pole breaker
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Choose from 15 to 60 amp
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Choose from 15 to 125 amp
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Larger image
Element tests 120 volt to ground at all times
Element will test for 120 volt to ground at all times because water heater thermostat only turns off 1 Hot leg of the 2 Hot legs needed for 240 volt circuit. The second leg stays Hot at all times.
The second leg stays Hot and is connected to both elements, so both screws on both elements will always test for 120 volt to ground. Exception, if breaker is tripped off, breaker is tripped off on second leg, wire or wire connector not connected, or if the red reset button (ECO) is tripped off.
Under normal conditions when water heater is receiving 240 volts, ECO is not tripped, and thermostats are functioning and within calibration ... the thermostat turns ON, current from the first leg combines with the second leg and completes 240 volt circuit to one of the elements (but never both elements at same time). Current flows across the element, and element heats water. When this happens, each screw still tests 120 volt to ground, but test across both screws on the energized element shows 240 volt.
Only one element at a time will be energized on ordinary non-simultaneous residential electric water heater.
Resource
How electric water heaters work
Figure volts amps watts for water heater
main breaker box
Why does it work like this?
Answer: Basic 120 volt and 240 volt circuits.
All household wiring is single phase. That means two wires are needed to complete any circuit.
With 120 volt there is 1 Hot and 1 Neutral.
With 240 volt there are 2 'out-of-phase' Hot wires. Hot wires are commonly called legs. Each Hot comes from a separate busbar. Two Hot wires from same busbar yield no voltage.
Resources
See inside main breaker box
Alternating current and 'out of phase'

All single phase circuits can be turned on-off by controlling one of the two wires.
So 120 volt can be turned off by one wire, and 240 volt can be turned off by one wire.
By code, the 120 volt switch must turn off the Hot wire, and not the Neutral. By code, it is allowable to turn off 240 volt by turning off 1 Hot wire, while other Hot remains Hot. It is also code to turn off both Hot wires. Water heater thermostats only turn off 1 Hot wire. The other Hot wire stays Hot and is connected to each element.

In 240 volt circuit, there are 2 hot legs and each leg has 120 volt potential to ground.... each 120 volt leg is 'out of phase' with the other. Out of phase generally means each wire has voltage potential against the other. If two legs are not out of phase, then there is no voltage potential. Read about out of phase

When water heater thermostat turns off one leg, it turns off one of the two Hot 120 volt lines... and the circuit is off... because single-phase circuits need two wires...
So one 120 volt Hot leg is off
The other 120 volt Hot leg is on at all time, and it is connected to both the elements... and so each element will test 120 volt to ground at all times.

Resources:
See inside main breaker box
How to wire thermostats
How to wire 240 volt outlets
Never assume power if OFF
Test using non-contact voltage tester.
This test only shows if power is ON or OFF
It does not show if you have 240 volt
Use non-contact tester

Buy:
Non-contact voltage tester Amazon
Electric testers at Amazon
Resources:
How to test electric power is off
Precautions before testing live electricity:
Tape multimeter leads to wood sticks to keep hands away from power.... paint stick does fine.
Do not touch anything made of metal.
Be sure to stand on dry non-conductive surface such as boards.
Remove metal objects from pockets.
Tape tester leads to wood sticks
Test for 240 volt Correct test for 240 volt at water heater
Test for 240 volt across top two screws of upper thermostat... not the element ... at the upper thermostat.
Use multimeter for best result, but ordinary tester will work

If no voltage, fully reset circuit breaker and test again.
If still no voltage, then breaker is suspect, move wires to a different same-size breaker, and try again.

If there is 240 at top two screws of upper thermostat, then push reset button.
If elements are still not working, then replace thermostats. How to replace thermostats
There is no valid test for thermostats.
After new thermostats are in, then push reset button.
Test for 240 volt across top two screws on upper thermostat.
If still no hot water after replacing thermostats, then replace elements. Replace elements
Correct test for 240 volt on element
Set multimeter to read volts AC
Test across both screws
If test is 0 volts, then element is off
If test is 240 volts, then element is on

If individual screw is tested to ground or metal tank, it will show 120 volt at all times, no matter if element is on or off

Buy:
Multimeters at Amazon>
Electric testers at Amazon
Resources:
How to test and replace element
How to test thermocouple
How to test wire
Element tests 120 volts Results of test across both screws
Set dial to 240 volts... analog multi-meter is easiest for occasional use.
When element is OFF ... test across both screws on element
On 120 volt water heater, test shows 0 volts
On 240 volt water heater, test shows 0 volts
When element is ON .... test across both screws on element
On 120 volt water heater, this test shows 120 volts
On 240 volt water heater, this test shows 240 volts

Buy:
Multimeters at Amazon
Electric testers at Amazon
Resources:
How to test elements
How to replace elements
circuit breaker resources Circuit breaker resources
Water heater is tripping breaker
How to replace circuit breaker
How to wire gfci
Can AC breaker be used for DC breaker
How to reset circuit breaker
Not enough space for circuit breakers/ use tandem
Circuit breakers
How to install subpanel
Why you need ground wire
See inside breaker box
How to wire safety switch
How to wire whole house surge protector
Figure volts amps and watts
Figure correct wire and breaker
Types of surge protection
Element tests for 120 volt
larger image
Elements on 240 volt water heaters test for live 120 Volts all all times.
Thermostats turn off one hot wire in 240 volt circuit
One wire stays hot all the time/ Other wire is turned on-off

But wait... both screws on element test for 120 volt... not just one screw like the illustration shows
Yes... true... because the element is a coiled wire, so the element will let voltage pass through to both screws... and all the way back to thermostat
Remember voltage is a potential to ground.
Voltage potential can sit on a wire and do nothing... until the circuit is completed by turning on a switch
When switch is turned ON (thermostat switch turns on), then the circuit is complete.
With 120 and 277 volt circuit, there is 1 Hot and 1 neutral needed to complete circuit
With 208 and 240 volt circuit, there are 2 hot wires needed to complete circuit
You can turn a circuit on-off by turning off only 1 wire... you do not need to turn off both wires... just one wire
OK so thermostat turns on... now the circuit is complete. Both hot wires in the 240 volt circuit are on,
If you just turn on the circuit without a load (element is example load), then there is a short circuit and breaker trips.
Element is a resistive load  (like a light bulb)
The two hot wires collide head-on at the element.... and the amperage and voltage cause the element to heat

Buy:
Multimeters at Amazon
Electric testers at Amazon

Resources:
How to test elements
How to replace elements
See inside main breaker box
What is amperage
How to wire thermostats
How to replace thermostats
Add another thermostat
Explanation. Thermostats only turn off one leg of 240 volt circuit
240 Volt circuit requires two legs to complete circuit.
Each leg is 120 volts
Thermostat turns one leg off, and other leg remains hot... so element will test hot 120 volts at all times
What is a leg for electric wiring? Each household circuit requires two wires to complete circuit.
Each wire in circuit is called a leg.
So each household circuit requires two legs.
2 legs for 120 volt circuit
With 120 volt circuit, one leg is Hot wire, and one leg is Neutral wire.
When Hot and Neutral come together at a light bulb, then bulb turns ON
If you turn off the Hot leg, then bulb goes OFF.
Light switch is used to turn off hot leg. The neutral wire is never connected to light switch... just the Hot wire is switched ON-OFF.
2 legs for 240 volt circuit 240 Volt is same, except circuit has 2 Hot legs
With 240 volt circuit, both legs are Hot, and each leg carries 120 volts.
When both Hot wires come together at water heater element, the element turns ON and begins to heat.
With 240 Volt, you can switch the circuit ON-OFF by switching one leg.
Turn off one Hot leg, and the element turns OFF.
water heater element tests 120 volts
Larger image

Water heater thermostats turn OFF one Hot leg in 240 Volt water heater.
The other leg remains Hot

Illustration shows BLACK Leg2 and RED Leg1 wires... 2 Hot legs in 240 volt water heater circuit.
Thermostat is OFF, so Black Leg2 is OFF

Illustration shows Red leg1 is ON at all times. Even when Black Leg2 is OFF.
Result is that test on element shows 120 volts.
But element is not heating because thermostat is OFF

Remember, each Hot leg in 240 Volt circuit carries 120 Volt.
Thermostats act like a light switch and turn off one leg in the circuit.
Hot Leg1 RED wire is standing ready at the element.... waiting for the thermostat to switch the other Hot leg ON

So when element is not heating, 120 Volt is still available at the element at all times, and the element test shows 120 Volt

Larger image

When water heater thermostat turns on the Black Hot leg2 ... both 120 volt Hot legs come together.
If there was no element present, the circuit would short out with a flash and pop, and breaker would trip.

Same thing with 120 Volt or 240 Volt circuit... when both legs come together, resistance must consume energy or the breaker will trip.

With element present, the two Hot legs meet and the resistance element consumes energy by heating water

When element is heating, and you test across both screws, then test shows 240 Volt
When you test each element screw to metal tank, it still tests for 120 Volt... because you are testing one Hot leg to ground

Larger image
Basic parts: Part replacement and wiring diagrams
1: Elements and wiring
Test water heater elements

   How to replace element and clean tank
   How to remove stuck, rusted element
   Wiring diagrams for elements/ residential single-phase, commercial 3-phase
   Wiring diagrams
   Figure volts amps watts for water heater

2: Thermostats and wiring
How to replace thermostats
   Test thermostats
   Wire water heater thermostats
   Change temperature
   Test wires

3: Anode rod and dip tube and TP valve
Anode rod/ replacement, odor etc
Dip tube
How to test and replace TP valve
Review all types water heater valves

Resources:
How electric water heater works
Water heater manufacturers
Find age of water heater
Use only 600 volt wire.
Lamp cord, extension cords are not rated 600 volt.
Use copper wire only. Aluminum wire is fire risk and should be avoided or installed by professional.

30 amp breaker use 10 gauge /
120-240 volt 30 amp outlet can be installed on 30 amp breaker only/ use 10 gauge wire ... cannot be connected to 15-20-40 amp breaker.

Orange/ #10 gauge wire, with ground ... 30 amp capacity. Safe maximum: 30 x 80% = 24 amps.
Buy:
10-2 gauge/ 30 amp
10-3/ 30 amp
Southwire electric tools
Yellow 12 gauge 20 amp
120 volt 20 amp outlet can be installed on 20 amp breaker, but not 15 amp breaker/ use 12 ga wire.
... cannot be connected to 30-40 amp breaker.

Yellow/ #12 gauge wire, with ground ... 20 amp capacity. Safe maximum 16 amps.
Buy:
12-2 gauge/ 20 amp
12-3/ 20 amp

NMB is house wiring
UF is underground
Rolls of stranded wire
White 14 gauge 15 amp
120 volt 15 amp outlet, AFCI, GFCI, timer, switch etc can be installed on 15 or 20 amp breaker. Never connect 15 gauge wire to 20-30-40 amp breaker.

White/ #14 gauge wire,  with ground ... 15 amp capacity. Safe maximum 12 amps.
Buy:
14-2 gauge/ 15 amp
14-3/ 15 amp

NMB is house wiring
UF is underground
50-60 amp breaker use 6 gauge /
240 volt 50 outlet can be installed on 50 amp breaker only
6-2 wire
Buy:
6-2 wire
Southwire electric tools
NMB is house wiring
UF is underground
40-50 amp breaker use 8 gauge /
240 volt 40 amp outlet can be installed on 40 or 50 amp breaker only
6-2 wire
Buy:
8-2 wire
Southwire electric tools
NMB is house wiring
UF is underground
    
Copper ground wire.
Every device, load, metal enclosure etc must be grounded. Ground wire must be continuous throughout installation, never switched on-off, never used as a Neutral wire.
Generally ... use same size as other wire in circuit
Buy:
12 gauge copper ground wire
Ground wire
Green ground wire
Ground pigtails
Ground rods/ ground clamps at Amazon
armored cable
Armored cable can be used as a grounded connection, and will protect wires from damage. Metal can be energized from an insulation failure.

Non metallic flexible cables must carry ground wire, but does not have hazard of short circuit causing injury from shock.

All conduit ...metal, plastic ... flexible and rigid ... must be attached to structure, and attached to enclosures, boxes.
Movement, damage and deterioration are major cause of electrical failure.
Buy:
Armored cable
Southwire armored cable cutter
Non-metallic flexible conduit
Power whip
Pull boxes
Southwire armored cable cutter
Electrical tools must be insulated.
Always best to disconnect power, but issues of insulation failure, lack of proper grounding, lack of GFCI, out-of-code wiring, generator operating without transfer switch, and other problems pose a risk to anyone working on electric power.

Buy:
Electrician tools kits
Klein tools
Tools kits
stranded wire
12 ga Stranded wire is good for conduit with multiple wires ... but stranded cannot be installed under screw terminals on outlets, switches, timers etc without risk ... of heat causing splayed strands ....that come loose ... and begin to arc. Connect stranded to short piece of solid copper wire, and attach solid to screw terminal. Do not solder residential or commercial wiring.
Buy:
Rolls of stranded wire

Protect wiring from damage
Use nipper instead of pliers or screwdriver for removing staples (and nails). Do not damage cable or wires inside cable.

-Code says: Cable SHALL BE secured without damage to the outer covering. NEC sec. 336-15
Buy
End cutting nippers at Amazon


Electrically insulated tools
When removing insulation from wire, do NOT score or put cuts on surface of copper wire. Doing so increases resistances and heat on wire and creates possible weak point.
Buy tools:
Wire strippers at Amazon
Linesman pliers
Utility knife at Amazon
multimeter
Multimeters
Voltage is tested across two separate wires. Ohms or resistance is tested across both ends of same wire. Amperage is tested along one or two points on same wire.
Buy:
Analog multimeter
Multimeters at Amazon
Klein multimeter
Electric testers at Amazon
Clampmeter for testing amp flow on line
Support the economy:
Buy water heaters from my associate links:

50 gallon Gas water heaters at Amazon
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Troubleshoot electric water heater
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Icon gas valve

How to replace water heater element Waste King disposal
How to wire tankless electric


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