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.

Filter by
Sorted by
Tagged with
3 votes
2 answers
1k 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 ...
user avatar
2 votes
2 answers
247 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?
user avatar
  • 123
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 ...
user avatar
  • 23
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 ...
user avatar
  • 2,414
2 votes
2 answers
109 views

How to get the state callback from a relay switch

We have made an automation module with relay connecting the mains and the raspberry pi. We are maintaining the state for the switch on our server. We have the raspberry pi connected to the device over ...
user avatar
1 vote
3 answers
2k 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 (...
user avatar
  • 111
1 vote
2 answers
57 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 ...
user avatar
  • 9
1 vote
2 answers
302 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 ...
user avatar
  • 2,746
1 vote
2 answers
777 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 ...
user avatar
  • 13
1 vote
2 answers
537 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 ...
user avatar
1 vote
1 answer
124 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 ...
user avatar
  • 1,190
1 vote
2 answers
61 views

How to add a lamp on the other side of the switch series?

I have a fairly standard setup here. A lamp controlled by 3 switches, the middle of which is a 4-way switch (but I think that's fairly irrelevant). I would like to add an extra lamp, controlled by the ...
user avatar
1 vote
0 answers
51 views

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 ...
user avatar
  • 11
1 vote
0 answers
87 views

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 ...
user avatar
1 vote
0 answers
41 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 ...
user avatar
  • 35
0 votes
4 answers
399 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 ...
user avatar
0 votes
2 answers
717 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 ...
user avatar
0 votes
2 answers
149 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 ...
user avatar
  • 1
0 votes
3 answers
190 views

Relay before or after power transformer

For my project I plan on controlling an off-the-shelve LED lamp using a relay board which is connected to my Raspberry Pi. As can be seen from the Lamp image below, there is a power converter which ...
user avatar
  • 103
0 votes
2 answers
4k views

Isolation relay for Ecobee smart thermostat: NC or NO?

I've been looking for "isolation relays" to install an Ecobee 3 smart thermostat on my 2-wire T/T furnace (replacing a Honeywell round thermostat). I know I want to use the 24VAC transformer/relay ...
user avatar
0 votes
4 answers
45 views

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 ...
user avatar
0 votes
2 answers
221 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. ...
user avatar
  • 151
0 votes
1 answer
33 views

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 ...
user avatar
  • 1
0 votes
1 answer
690 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 ...
user avatar
  • 475
0 votes
1 answer
275 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 ...
user avatar
0 votes
2 answers
804 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&...
user avatar
  • 15
0 votes
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 ...
user avatar
  • 31
0 votes
3 answers
324 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 ...
user avatar
  • 1
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: ...
user avatar
  • 103
0 votes
4 answers
340 views

How can I power a load from two separate circuit breakers?

On one circuit breaker I have a manual switch. On the second circuit breaker I have a motion sensing switch (using a mechanical relay). I have a number of lights wired in parallel as the load. The ...
user avatar
  • 184
0 votes
2 answers
81 views

Condenser fan and compressor don't start, electrical looks good though?

After replacing the fan, starting capacitor, and running capacitor, the system ran normally for ~1 day. Now nothing is starting. I got a fieldpiece multimeter and tested all of new capacitors, ...
user avatar
  • 111
0 votes
1 answer
122 views

How can I package a relay (for lighting control)?

Right now I have 3 high-pressure-sodium lights (475W actual x 3) on a single light switch. It's a heavy duty switch, but these lights have magnetic ballasts (40 pound transformer) and they have a ...
user avatar
0 votes
2 answers
59 views

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 ...
user avatar
  • 121
0 votes
1 answer
72 views

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 ...
user avatar
0 votes
3 answers
123 views

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, ...
user avatar
  • 117
0 votes
1 answer
58 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 ...
user avatar
0 votes
3 answers
329 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 ...
user avatar
0 votes
2 answers
71 views

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 ...
user avatar
0 votes
2 answers
118 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 ...
user avatar
  • 101
0 votes
1 answer
49 views

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 ...
user avatar
  • 1
0 votes
2 answers
710 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 ...
user avatar
  • 1
0 votes
2 answers
86 views

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 "...
user avatar
  • 101
0 votes
1 answer
324 views

PLC-Lighting Control-Plug n Play Operation with Relay

I am trying to build up a home automation system(retrofit) with existing conventional switches(230VAC). But I am looking for automation system without replacing existing conventional switches along ...
user avatar
  • 1
0 votes
1 answer
480 views

Attic Fan Furnace Interlock

I want to add a relay to my furnace so the attic fan can't run while the furnace burner is firing. Am I correct that the 24V side of the relay should be connected to the C and W terminals on the ...
user avatar
  • 1
0 votes
2 answers
750 views

Which current will pass through the relay when the generator and main supply are on?

I installed a relay for switching purpose With main supply and Generator. When there is no electricity from main supply relay change its coil to the generator. I want to know which will be the source ...
user avatar
0 votes
2 answers
104 views

Home Lighting Relay Characteristics

I have old electromechanical relays that were installed in a panel with a transformer as part of a remote controlled lighting circuit. It's a nifty setup except the relays are no longer manufactured. ...
user avatar
0 votes
1 answer
300 views

Submersible water pump relay question

Regarding -submersible residential style water pump relays- pumps fitted with a three wire cable which terminates into a submersible pump relay box--the red wire feeds the starting winding in the pump ...
user avatar
0 votes
0 answers
29 views

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 ...
user avatar
0 votes
0 answers
33 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.
user avatar
  • 139
0 votes
1 answer
91 views

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). ...
user avatar