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How to install electric meter on 240Volt 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
Kill a watt meter120Volt meter for refrigerator, microwave, computer etc

Resources:
Kill a watt Instruction .pdf

Buy:
Energy meters
240 volt water heater circuit
Basic 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
240 volt Meter on water heater
I installed meter on my water heater 12-16-2011. Beginning reading 00005 Kwh
Meter reading on 5-30-18 showed 11732 Kwh
Usage over 6.41 years ... average 1827 Kwh per year x 14¢ = $255.8 per year = $21.32 per month for 2 people with 30 gallon 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.
Buy
Bomain power meter
240 volt pass thru Kwh  meters

Resource:
How many kilowatts to heat water
Meter on water heater
The Kwh meter is din rail mounted inside enclosure.

 
Buy
Bomain power meter
Ketotek power meter
240 volt pass through Kwh  meter
2T2502GA beige plastic enclosure
2T2500GA grey plastic enclosure
din rails

Resource:
Enclosures
Figure volts amp watts for water heater
Step 1:  Never assume power is OFF
Use non-contact voltage tester on timer, on wire, on outlet to see if power is present.
Press button on tester, if single beep then no power is present. If continuous beep then power is present.
Never stand on bare ground, always stand on dry boards, do not hold or touch anything metal when working on timer or water heater that has power, tape tester leads to wood sticks, never touch wet water heater, or flooded water heater, or timer that had a short or fire without turning power OFF.
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Buy:
Klein testers
Multimeters at Amazon
Buy non-contact voltage tester at Amazon
Electric testers at Amazon
-Buy digital meter for easy read-out.
-Install meter and meter box level so it looks right.

Buy meter and base:
New and used electric meters 120v and 240v
Single phase 200 amp 240 volt meters
Meter bases/ socket
100 amp round base
Step 3: Review electric meter
Stab meter into meter box.
4 prongs on meter stab into meter box.
It takes strong push to install meter.
Meter 'plugs in' like extension cord
There are no screws or fasteners that hold meter in place.
Meter box
Larger image
Neutral wire is not used for 240Volt circuit
Step 4:  Attach wire to meter box/ socket
READ INSTRUCTIONS THAT COME WITH METER

1) Attach meter box to wall or supports with screws.
Meter box must be strong and secure.
Keep meter box level so meter is level and looks right

2) Use conduit, or approved connections at meter box.
This example shows 1" galvanized pipe and attachment brace.

3) Connect 240Volt wires from circuit breaker to top prongs inside meter box.

4) Screw down terminals very tight against wire.
Meter box
Larger image
Image shows 240Volt circuit. Neutral wire is not used for 240V circuit
Step 5: attach 2nd wire to meter box
10 gauge wire for water heater has 2 Hots and 1 ground
2 Hot wires and 1 ground wire enter and leave meter box
Install new wire between water heater and meter box.
Example shows orange-colored 10 gauge wire recommended for water heater circuit.
Use same gauge wire as original wire from circuit breaker.
Do not use smaller gauge wire.
Larger wire is fine since it runs with less heat loss.

Resources:
See wire sizes

Connect one end of new wire to lower prongs on meter box. Connect other end to water heater.


Household NM-B Wires are color-coded so inspectors/ electricians can easily identify which wire is used during construction
See more wire gauges
General Wire information
Use 10 gauge wire for 4500 watt water heater
Use 12 gauge for 3500 watt water heater.
Use only 600 volt wire ... extension cords are not permitted by code.
Use only solid copper wire.

There is no neutral in 240 volt circuit.
The black wire is Hot.
The white wire is Hot

Resources:
See wire sizes
Read more about electric wiring
10-2 NM-B

Black tape marks white wire that carries power
10-2 w/g NM-B household wire. Add black tape to white wire when using white wire for Hot instead of Neutral.
connect 10-3 to meter box
Larger image

10-3 wire
10-3 w/g (with ground) NM-B indoor household wire
How to connect 10-3 wire to meter
If your 240Volt circuit has neutral, then neutral does not connect to meter.
Applies to single-phase/ split phase 240volt residential
The Neutral wire does not connect to meter
For example when installing meter on electric dryer.

Resources:
How to wire 240Volt outlets
See wire gauges and charts
Water heater on porch
Larger image
Keep meter box level so meter is level and looks right
Finish details
1)  Make sure meter box is attached firmly to solid surface.
2)  Make sure wiring matches manual that comes with meter
3) Check for latch on back of 120V-240v meters
4) Stab meter into meter box. It takes strong push to install meter. Meter 'plugs in' like extension cord, and there are no screws or fasteners that hold meter in place.
5) Turn 240Volt circuit breaker ON. Meter records usage as water heater consumes power.

6) If water heater is not working. Remove cover on water heater. Remove wire connectors and test Black wire to bare ground. Test White wire to bare ground. This will ensure that water heater is receiving power and that ground wire has continuity back to breaker box.

Resources:
How to troubleshoot electric water heater
How to select wire size
Latch on back of electric meter
Larger image

Meters rated for 120Volt and 240Volt have latch on back of meter.
Meters rated for 240Volt-only do not have latch
Electric meter latch
Meter latch on back of electric meter
Latch on back of electric meter can be open or closed.
Electric power will flow to water heater if latch is open or closed..
Meter will not record Kilowatt-hours unless latch is closed. Be sure to tighten screws holding latch.
Single-phase meter box
Household Meter box has live power at all times
How to remove power company meter
To remove power company meter:
Power company Meter will have locking band
Call power company for 'meter pull'  Read more
Pull down firmly, and then shove upward
Repeat until meter comes loose
Turn off breakers before installing or removing meter

Resources:
More about household electricity
More about power grid

Larger image
Meter box wiring
Install heavy-amp meter on subpanel
Meter electric usage of garage apartment
Meter electric usage of home office for tax purpose
Meter electric usage of workshop for tax deduction
Monitor electric use of tankless electric water heater


Resources:
How to wire subpanel
How to wire tankless electric
Larger image
Installing Hour meters on water heater
If hour meter is installed directly to incoming wires at top of water heater, the meter will run full-time since it will receive power full time.
How to meter 240Volt water heater Use 240 Volt Hour meter
Requires two 240Volt hour meters. One meter for each element.
Install meter on each element as shown in illustration.
240Volt potential exists across element terminals. When thermostat closes the circuit, then 240Volt element is turned ON. The hour meter will turn ON at same time.

Buy:
UWZ48E-240V AC hour meter at Amazon
Intermatic bezel to support UWZ hour meter
240 volt hour meters
Intermatic ac hour meters at Amazon
Intermatic terminal wires Do not install stranded wire and solid wire under same screw terminal. Do not install 2 different gauge wires under same screw terminal. Doing so can result in loose wires and heat damage to element and wires.

Connect wires with wire connector, then put one wire under element screw plate.
Install Hour meters
Illustration is for illustration purpose only.
Wiring should NOT be open as shown in illustration.
All wiring should be enclosed inside covered electrical box.

Actual installation might require drilling holes in water heater covers and installing electrical box directly to front of water heater.

Factory insulation and covers must be put over both elements and thermostats so water heater thermostat will read correct temperature

Altering water heater will void warranty
Water heater cover
Larger image
Cover thermostats with insulation
Factory protector, insulation and covers must be put over both elements and thermostats so water heater thermostat will read correct temperature.

Thermostat exposed to cooler room temperatures and will misread tank temperature, leading to scalding and overheating dangers.

Resources:
Water heater safety precautions
Troubleshoot electric water heater
Wattage printed on side of element
Label on side of tank also shows watt rating.
Measure voltage of incoming power for 240V

Resources:
How to figure volts, amps, watts for electric water heater
How to test elements
Hour meter results How to read hour-meter results:
Wattage of element must be determined
Use multimeter to check voltage of water heater
Look at label on side of tank for different wattages at different voltages
Lower voltage means lower wattage than shows on element.
Confirm element wattage printed on end of each element

For example 4500 watt element and 240 volts
Hour meter reads 6 hours
4500 watts x 6 hours = 27,000 watt hours
27,0000 divided by 1000 = 27 kilowatt hours

Buy:
UWZ48E-240V AC hour meter at Amazon
Intermatic bezel to support UWZ hour meter
Intermatic ac hour meters at Amazon

Experiment: Set lower thermostat to 120 degrees, and set upper thermostat to 135 degrees and use hour meter results from each element  to determine if water heater runs less than having both thermostats set at 135 degrees.

Resources:
Ohm chart for testing elements
How to test elements
Read 9 ways to save with water heater
Information links for Elements and thermostats
Resources:
How to test elements
How to wire water heater thermostats
How to troubleshoot electric water heater

More Do-it-yourself water heater
Resources:
Math charts for setting water heater timer by incoming water temperature
Calculation for heating water with electricity
Electricity leaves power plant Resource: Electricity:
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 residential electric
How to wire commercial 3-phase

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

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