Search / all results
Search using Find button  

 Tweet button  
How to wire single water heater timers

Back to: Step 1: Gather Materials

Back to: Step 2: Connect wires
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 /

10-2 gauge/ 30 amp
10-3/ 30 amp
Southwire electric tools
Yellow 12 gauge 20 amp

Yellow/ #12 gauge wire for 20 amp
with ground
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

White/ #14 gauge wire for 15 amp
with ground
14-2 gauge/ 15 amp
14-3/ 15 amp

NMB is house wiring
UF is underground
armored cable
Armored cable
Southwire armored cable cutter
Southwire armored cable cutter
Rolls of stranded wire

Stranded wire
stranded wire
Rolls of stranded wire
50-60 amp breaker use 6 gauge /
6-2 wire
6-2 wire
Southwire electric tools
NMB is house wiring
UF is underground
40-50 amp breaker use 8 gauge /
6-2 wire
8-2 wire
Southwire electric tools
NMB is house wiring
UF is underground
Copper ground wire
Use same size as other wire in circuit

12 gauge copper ground wire
Ground wire
Green ground wire
Ground pigtails
Ground rods/ ground clamps at Amazon

End cutting nippers at Amazon

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:
Wire strippers at Amazon
Linesman pliers
Utility knife at Amazon
Electrical testers

Larger image
Neutral required:
This plan draws hot and neutral from any outlet box.
Applies to all programmable timers, countdown, wifi and zwave home automation devices.

Programmable timer
Countdown timer
Zwave switch
Wifi switch
z-wave switch
Larger image
Neutral required:
This plan draws hot and neutral from any outlet box.
Applies to zwave home automation devices.

Zwave switch
ST01C timer controls 240Volt water heater
Larger image

No neutral required:
Intermatic ST01C is best choice/ no neutral required
7-day programmable timer/ or dawn-dusk or dusk-dawn
Timer rated max 15 amp AC voltage: Use Fuse and fusholder
Busman fuseholder        
3-way switches at Amazon
Intermatic ST01 timer at Amazon

More wiring for ST01C + ST01C programming
Intermatic timers: ST01C & Ei600
Materials list/ and step-by-step for timer project
ST01 timer More uses for ST01 timer

ST01 timer controls water heater or any 240 volt load
Resource: Control motor with ST01 timer

Reverse ST01 using Intermatic air switch   /
: Intermatic air switches

Use ST01C for 4-way timer

ST01 24 volt DC photoeye

Convert single-pole switch into 3-way switch using ST01/
 Resource: How to add a switch   How to add 3-way switch

ST01 timer controls HVAC
FD water heater timer FD and FF spring-wound countdown timers 
Timer powered by mechanical spring instead of voltage
Connect either terminal to either wire

Buy:/ compare all brands countdown timer:
Countdown timers
Larger image
2-pole 40 amp contactor
With removable dust cover on top.
Select correct voltage needed to control coil.
Water heaters typically use 240 volt coil, HVAC replacement is 24 volt coil. Typical 2-pole contactors are rated with 24, 120, 208-240 volt coils. Three pole contactors for 3-phase are available in more coil voltages not found in residential applications such as 277, 480 etc. Using the wrong coil voltage will cause problems. Selecting a contactor rated for more amps is better, so using 240 volt 40 amp contactor for 240 volt 30 amp water heater is fine.

Buy 2-Pole 40A resistive
120Volt coil
40 amp 240Volt coil
24 volt coil
Packard contactor
Mars 2-pole and 3-pole contactors
Rheem HVAC replacement contactors
50 amp contactor
60 amp contactor
45EG20AF in box
Larger image
2-pole 40 amp contactor in 6x6x4 enclosure
Using #8-32 x 3/4" bolts
Install contactor at angle leaves room for wire

This is DPST contactor
Double pole, single throw.
So the contactor is double pole, or 2-pole. It can turn off 2 wires.
And single-throw because both poles are on-off at same time.
So you can switch both wires in 240 volt circuit.

6x6x4 pull box
6x6 enclosures


How to wire contactor for water heater
Types of enclosures
Compare types of enclosures
How to identify Black hot wire inside box:
Requires ordinary tester. With residential 120 Volt wiring, each box has only 1 hot wire. By code the hot wire is black. This test assumes you are testing ceiling box,  wall box with plug, wall box with multiple plugs, outdoor box, wall box with several switches, wall box with one switch. Test does not necessarily work with 3-way switch, since switch on other end can affect outcome. Test does not work with 240V circuits.
Turn off power. Mark wires with tape and numbers. Take photo of wires. Disconnect all wires from each other and separate. Turn power back on. Using ordinary tester, test each wire to bare ground. Only one wire will show power when tested to ground. That is the Black hot wire. Mark it. Turn off power. Reconnect wires.

See basic water heater circuit
Figure Volts Amps Watts for water heater
Keep wires straight
Use solid copper wire
If wiring terminal or end of wire are covered with green, use emery board to clean terminal and sandpaper to clean wire.
Insdulation under screw plate
Larger image
Both wires MUST be same gauge
Straighten each wire
If wire is corroded or overheated, clean the end with sandpaper and wipe with cloth.
If wire has been melted, cut back and reattach, or replace wire.
Tighten screw very tight against copper wire

Use wire connector  
Push on wire connectors
Use push-on wire connectors
3 wires/ or different gauge wires
Join wires with wire connector or push-on connector
Run jumper to screw terminal.
Push on wire connectors at Amazon
Red 3P connector (shown) for 10-14 gauge wire
Connector assortment
How to select and install wire connector
Fire safety/ Do not put stranded wire under screw plate
Do not install stranded wire under screw.
Problem1: picture shows 2 different gauge wires under screw plate
Problem2: Stranded wire will expand and contract and come loose under screw plate, even if it is the only wire under the screw plate
Attach stranded wire and solid wire with wire connector, and run solid copper jumper wire to screw terminal
Take photo of wires before starting.

Timer caught fire
Load ratings for Intermatic timers/ pdf

Larger image
10-3-wire  12 Ga
10 gauge or 12 gauge?
Compare your wire with short pieces of 10 and 12 gauge wire from local box store

10 gauge for 30 amp breaker.
10 gauge wire can have black-white and sometimes black-red

12 gauge for 20 amp breaker
12 gauge will have black and white wires
Match color code and amp rating for wire
Basic house wiring
Add black tape when White wire carries voltage (applies to 208 and 240V circuits)
With 120 and 277 Volt circuits, White wire is Neutral, and Black is Hot
With 208 and 240 circuits, both wires are Hot, and both wires carry voltage
Black tape on White wire identifies wire is Hot and not Neutral
Support the economy:
Buy water heaters from my associate links:

50 gallon Gas water heaters at Amazon
40 gallon gas water heaters at Amazon
50 gallon Electric water heaters at Amazon
40 gallon electric water heaters at Amazon
Hybrid / heat pump/ water heaters at Amazon

How to install gas water heater
How to install electric water heater
Troubleshoot gas water heater
Troubleshoot electric water heater
Point of use water heaters
Troubleshoot Gas valves with manuals
Icon gas valve

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

Install point of use water heater
Titan tankless

Contactors/ relays
Type 1 and type 2 surge protection surge protection
Programmable timers

Woods timers
surge protection
Anode rods anode rods
Recirculation system

Tankless recirculation
Point of use water heater
Install and troubleshoot garbage disposal Waste King disposal
Electronic parts

Industrial supplies

Tools and home improvement

Home and garden

Hayward pool
Pentair pool

Southwire electric

Black and Decker

Irwin Hand tools
Klein hand tools
Fluke electrical testing
Dremel hobby tools

Campbell Hausfeld air powered
Tekton automotive

Powerbuilt automotive
Saws and saw blades
box timers Resource:
Compare box timers
DPDT timers
Control water heater w/ Z-wave
Intermatic control centers Resource:
Intermatic control centers: and parts
Digital control centers and parts
Tork control centers and parts
All control centers and parts
programmable timer Resource:
Programmable timers
Countdown timers
Off delay timers
On delay timers
Timer modules
Din rail
Twin & one-shot
Low voltage power packs Recirculation systems
Enter Amazon from my links

My response might end up in spam folder, check email folders
Waterheatertimer on Twitter