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Contactors and relays

Packard contactor
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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
Resources:
Fasco info sheet
Packard .pdf
3-pole contactors
Mars-Contactors-tech.pdf
MARS_780_spec-sheet.pdf
contactor
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What is a contactor?
Contactor is a switch. It is rated for high amp loads.
High amp causes heat. Heat will damage regular electrical parts.
Timers and wall switches can be damaged by high amperage.
Each switch and timer has amp rating.
Contactors are rated for more amps than ordinary wall switch or timer.

The electrical circuit lasts longer when a contactor is used because contact points on a contactor are designed to switch high amp loads without melting or being damaged by heat.
The electromagnetic coil can be switched on-off using ordinary wall switch or timer.
When voltage is applied to coil, then contact points close, and heavy amp circuit turns on.
This lets you control heavy amp loads using ordinary wall switch or timer.
Use correct size large screwdriver or #3 square head driver.
Use T handle driver instead of cordelss tool for best torque without damage
Cordless driver can sometimes crack apart circuit breaker, outlet, switch etc, and might slip from screw before wires are firmly attached.
Buy:
Square drive set
T handle nut driver
Ratchet screwdriver

Resources:
Safe electric wiring
Color code wire
Extension cord code
45EG20AF in box
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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 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.
Buy Metal
Bud industries 6x6x4
Nema 3R Outdoor box
Hinged door/ 6x8x4

Polycarbonite enclosure
Bud industries boxes at Amazon
Arlington boxes at Amazon


Resources:


How to wire contactor for water heater
Enclosures
Specifications for 2 pole contactor
Each contactor has amp rating: this is the number of amps that can be safely handled by the the contactor points
Each contactor has coil voltage rating: this is the voltage needed to operate the switching coil
Approx 1-3/4" wide  x 3-1/2" long x 3" tall
Coil burden or coil VA is 7.3 Watts, inrush is 27 Watts.
Life expectancy <> 0.5 - 2.0 million operations
Resource:
Life expectancy of Siemens definite purpose controllers
Contactor dimensions
single-pole contactor
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1-pole contactor
Only leg is turned on-off, while other leg is continuously connected

Buy:
Single pole contactors at Amazon
3 phase contactor 3-pole contactor for loads up to 90 amp
For loads up to 90 amp
For coil voltages: 24, 120, 208-240, 277, 480 volt
Control 3-phase with contactor

Resource:
3-pole contactors

What is 3-phase
How to wire 3-phase timers and contactors
How to convert 3-phase water heater to single phase
Smarthings Hub
30 amp, Z-wave contactor with enclosure
Selectable voltage: 120, 208, 240, 277 volt
Operate DPST or 2
x SPST contactor with z-wave
Two sets of contacts can be operated at same time, or separately.
So you can control different voltages at same time.

Buy:
Intermatic CA3750 at Amazon
Smarthings Hub at Amazon
https://amzn.to/3sZ0F6c
Contactor controlled by remote Z wave

Resource:
How to wire and set up CA3750
Wires connect to contactor using female terminals
Hot and neutral can connect to either side.

Buy:
120Volt coil At Amazon
240Volt coil At Amazon

Mars 2-pole and 3-pole contactors at Amazon

Resources:
Furnas cross reference
Siemens cross reference
3-pole contactors
Terminals
Buy:
Terminal kit at Amazon with crimp tool
Electrical terminals at Amazon
Blue 14-16 gauge female terminals 20 pcs at Amazon
Yellow 12-10 gauge female terminal 16 pcs
360 pc assortment at Amazon
520 pc assortment at Amazon
Resource:
More about #10 & 14 female terminals

PB 300 connected to water heater
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Connect modular timer to contactor
Resource
PB series and other timer modules
24 volt programmable timers
Sprinkler timer connects to contactor
Convert 24 volt sprinkler timer to 120 volt

Resource:

How to wire Intermatic sprinkler timers
3-pole contactor
Control 3-phase using contactor

Select:
3-phase contactors

Resources
How to wire 3-phase timer
How to wire 3-phase
What is 3-phase
Compare 40 amp box timers
Compare all box timers
Override T104 timer Override T104 timer

Resources:
T104 timer wiring
T100 series timers
Compare all box timers
Pool control centers
Freeze controls
Control motor with 2 switches
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Larger image 2
Control motor with 2 switches
Same wiring diagram applies to single-pole switch

Buy Contactor with 240Volt coil

240Volt coil At Amazon

Start winding pulls more amps than switch can safely handle.
Over time, the switch will fail.
Contactors are rated for heavy amp loads, with expected life of millions of operations

Resources:
Delay timer for motor or pump
Control motor with 2 switches or timer
Motor troubleshoot and resources
30 amp, 2-pole, open frame power relay with enclosure
SPDT relay.... different from DPST contactor.
Both perform same job. Both have 2 sets contacts. Open frame relay SPDT has extra set contacts so a second load can be turned on-off exactly opposite from off-on other load.
12-24-120-240 volt coils/ 30 and 40 amp models
Note that a 30 amp power relay, or switch, or contactor has safe maximum 80% rated value, or 24 amps. For 30 amp circuit, must use 600 volt, 10 gauge solid copper wire. Never undersize wire or use extension cord for permanent wiring.

Buy from my affiliate links
Magnecraft box and cover
Siemens power relays
Schneider W199 relay
NTE open frame relays
Packard DPDT fan relay
Tyco open frame relay
Contactors/ reliable for heavy amp loads
15 amp Relays for loads up to 10 amps

Resource:
Open frame wiring
DC relays for solar panels
Reverse motor using DPDT relay
Control motor with 2 switches
Start two motors at different times
How to reverse motor with switch
Relays for DC motors and solar panels

Omron LY23 AC Model terminals/ back to front:
7-8 magnet terminals (turned opposite direction from other pins)
5-6 common terminals
3-4 NO normally open terminals (power is off when relay off)
1-2 NC normally closed terminals (power is On when relay is off)
Load rating 7.5 amps AC
900 watts incandescent @ 120V
1800 watts incandescent @ 240V
1/4 Hp motor @ 120V; 1/2 Hp @ 240V
To reverse operation of photo-eye
So Load comes on during daylight hours
photo eye connected to DPDT relay

30 Amp relay x 80% = 24 amp max up to 2880 watt @ 120V or 5600 watt @ 240V
30 amp 10 gauge wire up to 2 Hp @ 50' or 1.5 Hp @ 100' @ 120V See load charts
Use Omron 120volt LY2-AC 8-pin relay for 7.5 amp.
(Note that the LY2 and LY3 15 amp relays are rated 10 amps for 2 and 3-pole relays. And 5 amps for LY4 4-pole relay.)
    NO NC Relay
    7.5Amp Omron         30Amp DPDT
Buy
Omron LY2 at Amazon / Choose 120Volt coil
30 Amp relay at Amazon
12amp DPDT Packard at Amazon
Resources:
Omron relay/Page 450 / pdf
Uxcell LY2 relay/ 10 amp relay with base ... fits din rail

With these small 10 amp relays, do not put 2 wires under same screw plate ... use individual wires joined by twist on wire connector.
It is against code to use 100-300 volt extension cord as permanent wiring.
Code requires ordinary 600 volt electrical wire as seen embossed on wire sheathing.

Recommend using solid copper wire under screw plates, and not stranded ... motor loads can cause stranded wire to get warm enough to splay apart and loosen under a screw plate.

Of course all electrical connections (relay etc) must be contained inside electrically-rated enclosure (not homemade wood box etc) ... with a matching cover applied.
Buy:
Uxcell 120 volt coil
Uxcell relay
6x6 x 4 enclosure
4x4 x 4 encloure
Tapered drill bit
Resource:
Enclosures
Reverse Motion detector Reverse motion sensor so Load turns OFF

Motion sensor
Buy:
Motion sensor at Amazon

Resource:
How to wire motion sensor
Fuseholders

 
DPDT Switching relay
12 amps @ 120 volt, 6 amps @ 208-240 volt/ 3/4 HP
White Rodgers, Packard, Emerson, Edgewater, Mars, Honeywell, Jard, RBM etc
Buy:
Packard DPDT fan relay
Terminal kits

Resource
Mars-relay.pdf
mars-general-purpose-switching-relay.pdf
Packard-switching-relay.pdf
Schneider din rail power relay
DPST
DPDT
1 hp @ 120V 50/60Hz
3  hp @ 240V 50/60Hz
Buy
Schneider Din rail mount power relay
Dayton enclosed power relay
Omron enclosed power relay
Din rails
Terminal kits
24 volt 1EJG9 relay at Amazon
Resource
Power relat spec sheet
Solid state relay Solid state relay/ SPST
Check for AC-AC input-output
DC input to AC output is most common
Buy:
AC to DC/ AC to AC
AC to AC 
100-240Volt AC input / 20 amp/ at Amazon
Relay safety cover
Heat sink

Resource:
Electromechanical relay vrs solid state relay/ pdf
convert AC water heater to DC/ high voltage
Convert AC water heater to DC/ low voltage
Zettler
SPDT model C shown/ 30 amp NO terminal/ 20 amp NC @ 277 V
Also available SPST model A/ 30 amp NO terminal @ 277 V
Base 1.08" x 1.98" / 1.09" high
Zettler 30 amp miniature power relay
Coil voltage 120-240 VAC / also DC ratings
Contact ratings 277 volt AC/ 28 VDC
Use quick connect terminals

Buy:
Atwood miniature relay
120Volt SPST miniature relay at Amazon
Zettler relays at Amazon

Resources:
Zettler relay wiring
Override thermostat with programmable timer
Manual/ spec sheet
Terminals
 DC power relay
250VDC    25 amp                                                                     400VDC  200 amp               
DC to DC relay/ mechanical type
DC power relays
Full on-off contacts/ 12 or 24 volt DC coil
250 volt / 25 amp DC load
250V x 25 amp = 6250 watt
Connect 12 or 24 volt DC to terminals 3-4;
Connect load to terminals 1-2

Buy:
Electromechanical DC-DC G9EB-1 relay
G9EB-1-B-DC24
24 VDC coil and 400 VDC/ 200 amp contacts
Fuseholder

Resources:
DC relays for solar power
Omron-DC-DC-relay-Datasheet
Omron DC-DC pdf
DC power relay spec sheet
G9EA_G9EB_G9EC.pdf
12 Volt DC relay
Coil 12-24 VDC
Load contacts 26 VDC  40-50 Amp
12 VDC 40-50 amp DC power relay
Buy:
W199AX-3 relay
W199PX-13/ 50 amp at 26 VDC = 1400 watt
X199 Magnecraft relay
Magnecraft W199 DC relay

Resources:
Magnecraft relay / pdf
Resource
enclosed relay Enclosed relays/ Functional devices
Buy:
Enclosed relays at Amazon
3PST AC-DC at Amazon
Functional relays at Amazon
Aprilaire relay Amp relay
When amp exceeds amp set point, the relay activates 120 volt circuit.
Recirculation pump is 1/25 Hp or 30 watts divided by 120 volts = .25 amp\
1 Hp motor is 750 watts divided by 120 volts = 6.25 amp
Use relay to control contactor when load exceeds 50 watts
Use to activate duct booster fan
Take off bracket and install bracket around a control wire that carries amperage
When amperage flows across line, the Aprilaire relay activates... and closes circuit going to 120 Volt load... such as indicator light... or another relay etc... the indicator light turns ON.
Wrap the wire multiple times to increase measurable current
Use a current transformer to reduce current
current sensing switchBuy:
Amp relay/ CSS or current switch/ current transducer
Buy:
Aprilaire relay 4 amp at Amazon
Suncourt relay 1.2- 40 amp at Amazon
Louensy 0-200 amp
johnson current sensing<
Low amp current indicator
Current sensing relays
Current sensing switch
Current Transformer<
Current sensor module

Resources:
Aprilaire manual .pdf
Johnson control amp sensing switch/ pdf
NK technology AC current sensing switch/ pdf
Life expectancy <> 0.5 - 2.0 million operations

Contact points stick sometimes

Solution: use nail file or emery board or folded sandpaper to clean off points.

Handy trick
Add indicator light so you can see when water heater is on. If points stick, indicator light remains on.

Electrical formulas
Indicator light Buy:
120 volt Pilot light at Amazon
120-240 pilot light
indicator light 120v
Resource:
How to wire water heater pilot light

Add to water heater indicator light page:
Low amp current indicator
Additional links
Electricity leaves power plant What is 3-phase electric: power plant to end user

Buy
Tools

DEWALT
Black and Decker
Stanley
SKIL
Makita
Porter-Cable
Bosch

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

Campbell Hausfeld air powered
Tekton automotive

Powerbuilt automotive
Saws and saw blades


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