Questions tagged [relay]

A relay is a control device that allows a small voltage or current to control a larger voltage or current. Use this tag for questions about standalone relays in electrical or HVAC wiring -- questions about relays in appliances do not need this tag.

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Protecting Smoke Alarm Relay from Large (6.5 amp @ 120V) Inductive Load

We recently installed a whole house fan that has a max current of 6.5A at 120V. Due to the dangers of whole-house fans accelerating fires, we wanted to be safe and wire in a smoke alarm relay so that ...
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2 answers
80 views

Wiring a 120 V device to a HVAC thermostat

I'm looking control a 120 V device with an HVAC thermostat. The device is a scrubber that cleans air and should\must only run when the HVAC is running (running in the cool state, heat state, or just ...
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2 answers
191 views

Fridge Tripping GFCI but not when compressor is unplugged

I have a 12 year old GE Fridge in my garage that stopped freezing & cooling a few weeks ago. I diagnosed it as a bad relay and replaced it. Things ran normally for about 2 weeks and then one day ...
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On-Delay, Under and Overvoltage Relay, Contactors AC-7a & AC-7b, Relay - Contactor compatibility, RCCB rated current higher than operational current

Background I live in Indonesia, the voltage for residential buildings ranges from 220 V to 230 V, I need help with the installation of the Schneider products. Here is the link to the thread about the ...
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34 views

How do I connect to C230B contactor?

I bought a contactor to wire a rely from 110V to 240V sauna heater. What kind of connector do I need to connect to the terminal? There is no documentation at all.
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2 answers
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2 wire thermostat, control relay

I currently have a 750mv propane stove in my living room. It is connected to a battery powered Honeywell programmable thermostat with 2 wires. The thermostat supports AC and fan. I have in my living ...
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1 answer
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Power one 120vac light from two circuits

I have four 120vac front yard lights controlled by a switch on one circuit and five 120vac back yard lights controlled by a switch on a different circuit (same or different phase not currently known). ...
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Are there better types of humidifier relays

I'm on my third relay in five years for my humidifier. One started buzzing and the other two stay closed until I tap them. Is there a better type I can buy or what do I need to look for to get a ...
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1 answer
336 views

Electrical Wiring Shelly 1L Breaker Shared With Sockets

I have lighting/wall circuit which I didn't put in place so don't have definitive information on its layout so bear with me. I want to put the Shelly 1L into the circuit at the switch. What I know ...
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1 vote
0 answers
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Maytag MED3500FW0 help with diagnosing no heat

I have a hope that you'll be able to either confirm or refute my diagnosis. As a quick aside, I work in computer science and have a decent bit of electrical engineering experience, as well as ...
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1 answer
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How to create a C-Wire from Honeywell R8888A/B

So Ive been trying to install a new Honeywell wi-fi thermostat. I have been unsuccessful in any event. I have a third wire unused at every thermostat in my home which is black. This black wire tuns ...
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1 vote
2 answers
70 views

Pigtail Line Side of GFCI

Is it O.K. to put a pigtail on the line side of an outdoor GFCI to power an irrigation pump (via relay)? The outlet would be used for the irrigation controller and misc. outdoor electrical items. The ...
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Powering single HVAC damper from 3 circuits

I am updating a 1993 house in Texas and now have exhaust fans going through the roof, so I am also adding a fresh exterior air intake to the HVAC return plenum for make-up air. I want to open the ...
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4 answers
478 views

Wiring an inverter into an RV using an contactor (AC Relay)

I am working on installing a DC to AC inverter (Victron Energy Phoenix 800VA) in my little teardrop RV such that the Inverter powers ALL the AC ports when it is turned on. The objective is to have it ...
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Refrigerator Compressor not working?

I unplugged then plugged back in my fridge an it isn't cooling or freezing! Does that mean my compressor is no more working? The light comes on inside the icebox?? Just not cooling or freezing..
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2 answers
900 views

Circuit design for my sprinkler system

Basically, Installing a pump start relay into my system. Would like to run 6 #12AWG THHN wires through a carflex 1/2 conduit, from pump pressure switch, (under house, crawspace)area, up to 4"x4&...
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3 answers
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AC blower unit stops working intermittent

hoping someone with more knowledge then I, can guide me on this. Recently my central AC's blower unit stops working intermittent after its been on for a few days with no issues. When it stops working, ...
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-1 votes
2 answers
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how wire a 24 vac normally closed float switch to a relay to turn power on and off to a 120 vac clothes washer

Hi: In over my head just by being here so thanks in advance for your patience and help. My goal is use a 24 vac float switch (which sets in an overflow pan) to interrupt a 120 vac circuit that runs a ...
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0 votes
1 answer
59 views

How do you wire a current sensor to multiple fans?

I have two booster fans that I only want to run when the main HVAC blower fan is on. Each fan will have its own speed controller. How do I wire them both to the same current sensor switch? Should I ...
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3 answers
365 views

Using a 24 volt ac relay with a 16 volt ac doorbell circuit

I have recently purchased a doorbell camera for the front door. It has the ability to ring my current doorbell but I use an intercom system with an electronic chime module. After watching many you ...
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53 views

3amp fuse blows only when set to heat

The 3amp fuse blows when set to heat. I replaced it and it doesn't blow when set to cool. I'm not an electrician but looked on the web and have changed the transformer a capacitor and a contactor on ...
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2 votes
1 answer
94 views

Why does my first floor thermostat also make my third floor baseboards turn on?

(Possibly related to this question but I do not have the expertise to diagnose at the level of the author of that question) I moved into a new house recently that was billed as having three heating ...
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Why does my furnace blower work intermittently?

On my Goodman 3.5 ton AC/ furnace, the blower seems to only run when it wants. I changed the capacitor on the blower twice and the thermostat once- same. If it doesn't start, I turn it off for 5 ...
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Dual HVAC System with Dual UV lights - looking to power UV lights when HVAC runs

So I have (2) HVAC systems in the attic (2) UV Lights in the attic ducts downstream of the blower(s) (powered by a standalone 120v outlet) I would like to power the UV lights when the HVAC / blower is ...
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0 votes
2 answers
242 views

Single pole or dual pole relay for switching a 3KW water heater? (UK)

I have bought a Wifi controlled device to control a 3KW, 240V water heater (immersion heater) wirelessly but despite being advertised as 15A, it actually has a 13A relay which has "push fit" contacts. ...
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1 answer
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refrigerator not cooling

I have a GE side by side and the freezer is working fine, but the refrigerator is not cooling (not hot kind og like room temperature). I replaced the relay switch how long before I know if that was ...
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1 answer
64 views

How do I install a relay receiver?

I have a string of lights above a tv that are controlled by a switch. But, the switch also controls a few other things. I cannot leave the switch in the on position as I do not want the lights on all ...
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1 vote
2 answers
328 views

Is a 2.5 Ampere relay sufficient for 24V thermostat AC only application?

The goal is to 24V control signal YEL (cooling) and GRN (fan) for a Florida storage building, with three AC units. A single board computer (Raspberry Pi) is outfitted with 2.5 Ampere relays. Is ...
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1 vote
0 answers
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2 humidistats for 1 humidifier

I have two zones in my house with a damper system and want to move away from using my humidistat to control the solonoid valve on my humidifier and instead use my Nest thermostats. My zone control ...
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2 votes
2 answers
270 views

240VAC outlet double or single relay?

I have a 240VAC garage outlet that will be turned on via a control relay. Is it best practice to switch/relay both lines, or just one like 120V~ loads?
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2 answers
119 views

JQX-115F relay switch triggers when moved. Is it faulty?

My boiler is controlled by a programmer unit to turn on and off at certain times. There is a receiver unit between the programmer and the boiler, and I believe this receiver unit is at fault. The ...
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1 answer
858 views

Furnace relay - old one says 18 LRA, replacement says 48 LRA - Does it matter?

forgive me if this is a newbie question. I am replacing a relay inside an electrical furnace/air handler. It is a relay model 90-293Q. The original one I have specifies it as "8 FLA, 18 LRA" but the ...
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0 answers
66 views

What circuit components should I use for a vacuum?

So I'm constructing a dust extractor system for my workshop, and I need to figure out a circuit. I have 3D Printed a connector that connects two PVC Pipes, and has a hole for a wooden slab. I can ...
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0 votes
3 answers
341 views

Device to switch between two light with a single wall switch

first of all, sorry about to be asking that silly and newby question, I know, it is really lame. Is there a simple device, that I can build simply, or bought, that can switch between two lights ? I ...
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414 views

Should I use an Isolation Relay between a Furnace and Humidifier?

I recently installed a new Aprilaire 700 humidifier attached to a Carrier Infinity 96 furnace. It has been working perfectly for the past 3 days. Considering the fact that there are 2 distinct ...
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0 answers
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How to get Condensate Pump to talk to Sonoff 4CH Pro R2

I currently have a WiFi water alarm triggering a Sonoff 4CH Pro R2 to kill my whole house humidifier. So I have some experience with triggering the relays and getting the two devices talking to each ...
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0 votes
1 answer
2k views

How to wire isolation relay to create C-wire

I'm trying to follow the ecobee instructions here: https://support.ecobee.com/hc/en-us/articles/227874527-ecobee-thermostat-installation-with-an-isolation-relay Which uses a wiring diagram as such: ...
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1 answer
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Electric Furnace, no AC, blower motor starts then slows after 1 second

I have an electric furnace 240V. The blower motor starts then slows and sounds like it is laboring after about one second. It does start at full speed, however. Does the same thing when in constant on ...
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1 vote
2 answers
827 views

Can I wire a Pump Start Relay to an outdoor GFCI outlet?

I have an existing outdoor GFCI outlet. Can I wire a pump relay to the existing outlet, and put another GFCI outlet after the relay? The goal is to have the second outlet only powered when the relay ...
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3 votes
2 answers
2k views

Electric Garage heater contactor failure

I own a Fahrenheat FUH724 (7500 watts) electric heater for my 2 car, uninsulated garage. I installed this unit 12/2017 along with a Nest thermostat. An Aube rc840t-240 relay was used to step down the ...
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1 vote
0 answers
42 views

Box mounting point

What are the chances of this setup passing an inspection? 4x4 box is mounted on a stud, relay attached to the bottom 1/2 knockout, transformer will be mounted at the front of the box. This is in ...
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1 vote
3 answers
3k views

How bad is it for my A/C unit if I cut the power while it's working?

I have a rental apartment with two a/c units. I installed magnetic contacts on the windows of each room and a small module (a sonoff basic flashed with tasmota firmware) that shuts off the a/c relay (...
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1 vote
2 answers
557 views

What switch and relay circuitry is required to manage two water well pumps effectively?

Here is my dilemma. I have two water wells; consequently, I have two deep well pumps. Presently I have a relay set up to switch wells each time the pressure switch requires water. They are labeled #1 ...
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0 votes
2 answers
787 views

using a relay to swich between main and solar power

I have both solar and mains voltage at my house and since the solar isn't enough to continuously power the house , we switch between it and mains when there is less sun.I was hoping to make an ...
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2 answers
733 views

Smartify 50s low-voltage lighting system

I bought a house with a low-voltage lighting system, where the switches have low-voltage wires that power relays that actually power the full-voltage lights. I want to find out if I can take advantage ...
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0 votes
0 answers
31 views

Strange lamp behaviour

I have an exterior lamp that is controlled by a standard switch and a 'timed-relay' (I push a button and light stays on for 3 minutes), I think those two are wired in parallel as if the lamp is on and ...
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1 vote
1 answer
125 views

What is the function electrical device?

What is the function of the device in the picture. Unfortunately, I did not make a full diagram of how it was wired, but the hot and the corresponding neutral were connected by crimp-on leads on the ...
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35 views

would these be compatible replacement solid state AC Relays?

I am replacing a relay for an appliance (stove). I cannot find a replacement relay, however I thought I'd confirm if the following relays would be compatible: 1) input 90-250 VAC output 24-440VAC 25 ...
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2 votes
1 answer
1k views

Connect the heater boiler through a relay instead of direct to the thermostat

I am wiring up a new thermostat for an old boiler, and the thermostat I am using needs a common wire (Proliphix NT130h -- I wanted an NT1X0e series, which use PoE and don't need C, but they are no ...
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Help with Sain Smart 24V Relay Cycle Timer Module

I'm considering getting one of these: https://www.sainsmart.com/products/24v-relay-cycle-timer-module ...to force my 2nd floor thermostat to force heat on every so often (say, 1 minute every 15) to "...
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