Hot answers tagged

4

You will need to protect against short cycling the air conditioner When you turn an air conditioner compressor off, the pressure in the system does not equalize instantly -- instead, it takes a few minutes for the pressure built up on the high side of the refrigerant circuit to equalize with the pressure on the low side. If you turn the compressor back on ...


4

I'm very dubious that you should be the person responsible for connecting anything that eats 40 or 63 amps of 400V 3-phase power if you are asking this question. That is some VERY serious power and a properly trained electrician is likely a very good investment in being sure that it works safely and correctly. But, to answer your question, each wire from ...


4

I'm assuming your wanting to power some 240V appliance with this circuit. In that case, if you switch off only one of the two HOT wires, you will likely cause a problem with the appliance, depending on what it is. Yes, you would definitely want to use a double-pole 240V rated relay for this application.


3

It's not possible to predict what will happen if you break the circuit between the converter and the lamp. The converter may fail catastrophically if it is switched on without the load it was designed for. If you could be confident that the converter is nothing more than a step-down transformer, perhaps with a load limiting resistor, then you could insert ...


3

I would use the system as it is and add a low voltage relay that the computer controls to fire the existing relay. With this method the existing switches would still be functional as an overide, one example might be similar to an arduino relay board using the arduino micro controller my grand son and I built a 12 channel Christmas light controller, in your ...


3

You're correct, you'll use the normally open (NO) terminal. When the thermostat calls for heat, it will energize the relay coil. The energized coil will close the contact in the relay between common (C, COM, etc.) and normally open (NO). When the coil is not energized, the contact connects the common (C) terminal to the normally closed (NC) terminal. When ...


3

The LRA is simply the maximum amperage the relay is rated for when starting up a motor. Having a higher LRA just means you have a higher rated relay for starting currents. Having more will not matter. The FLA or full load amperage is the rated operating amperage which in your case is the same as the original. In many cases it's easier to just make a higher ...


3

First off, understand how a refrigerator moves cold air around between the freezer compartment and the cold food compartments. Here is a generic diagram. So make sure you have not stored something in a way that is blocking the airflow. If not, then find and inspect those air pathways to see if there is ice, mold or some other material built up and blocking ...


3

There's a chance that a backflow-preventer valve is stuck open, allowing hot water from Zone-One piping to flow "backwards" into Zone-3 piping. See if you can find these valves- they likely are close to your furnace. They are probably green, with a directional arrow printed into the metal housing (and have only one inlet and one outlet). Also, ...


2

Someone already did all the work for you Fortunately, you aren't the first person to run into this problem. In fact, there have been enough people who have had this problem that the good folks at Functional Devices slap an appropriate relay into an appropriate box, dress it up slightly, get it UL listed, and sell it! In particular, you want something like ...


2

Be aware that any voltage drop across the relay coil will make LS1 correspondingly dimmer, so choose the correct type of relay. For this series-wired application you want a current-actuated relay rather than a voltage-actuated type. A simple current-actuated relay has only a few turns in its coil, which is wound with wire sized to handle a lot of current. ...


2

That is a contactor. With the proper electrical signal to a coil underneath it magnetically draws the switching plate across the contact points and closed the circuit. This type of unit is typically rated for 15 to 40-Amps. It is an electrically operated switch for heavier loads.


2

I talked to a local HVAC repairman, and he said it should work, so I did it, and it works. Here's what the circuit looks like:


2

Actually use a double pole switch , one side for your control and the other side for your Feedback loop (indicator) vcc to supply the feedback when turned on. This is how it is done in the real world. (but that is the switch) to know if the relay is energized a similar setup is needed - one set of contacts for the control and the other for the feedback loop (...


2

This can be solved with four special purpose relays. Relays are basically electrically operated switches. Alternating relays are special relays that cycle between two or more loads sequentially when they are electrically activated. You could cascade one triplex alternating relay with three regular (duplex) alternating relays to achieve what you want - ...


2

That brings back memories! A friend had a similar system in his house growing up. This is know as a 3 wire low voltage system. Only way to integrate aditional control points(computer or aditional switch locations) is to extend the 3 wires that are connected to the switch. You will need 2 relays for momentary contact purpose. Red wire is to signal the relay ...


2

Most AC units today have a timer to prevent the compressor from turning on after a power cycle. I have not seen a larger unit that doesn't have this protection and most smaller units also have this but not all. Yes the fans turn on right away but the compressor may not start for 3 or more minutes. Very high efficiency units that I have installed really don't ...


2

You actually happen to have the relay oriented in your photo the same way the relay in the diagram is oriented. W1 to terminal 1 C to terminal 3 Boiler T&T wires to 2 and 4


2

There probably is a switch out there that can do it - with three states - Off, A, B. Wire A to one light, B to the other lights. But I think a far simpler solution - or at least far more common in terms of inexpensive parts is to use two switches. The first switch would function as On/Off. The second switch would function as A/B. The second switch would be (...


2

I think the answer that you want is that the 24v is only used to close relays, so the amperage needed is only for the combined amperage of the coils on the relays (or not combined if you're using one relay on the board for each control wire). I would assume that a 2.5A relay is more than enough for each control wire, but if you are trying to drive all three ...


2

The "how to" is you send that rubbish back to the dark place. It is not safe nor legal, and doesn't even fit our wiring. You bought it in a way that circumvented the systems that assure quality, safe products in the consumer retail stream. Don't do that with electrical gear. Then you buy any of a wide variety of products which do that same function, ...


2

That item probably should not connect to AC mains Each country has apparatus to protect its citizen from dangerous products. Most countries require good be certified by a competent independent testing lab such as UL, CSA, BSI, TUV etc, and retail stores can get in big trouble for carrying uncertified items. The EU allows companies to self-certify, but ...


1

As amplification to the correct answer of @ThreePhaseEel: Decades ago: if an A/C short cycled, the high load on restart would blow the fuse or circuit breaker for that branch circuit. One solution was a Slo-Blo fuse. It would blow at the same overcurrent level, but would tolerate that overload for a short time (seconds?) before blowing. So the A/C ...


1

It will work to use the contacts of the relay to switch the pump power, tapped from the load side terminals of the existing GFCI to run the pump receptacle. I personally might use a single (not duplex) non-GFCI receptacle for the pump. If you use a duplex receptacle it seems like someone will eventually unintentionally plug something in there expecting ...


1

This is why GFCIs have LOAD terminals A receptacle-type GFCI has two sets of terminals: LINE and LOAD. The use of the LINE terminals is simple -- these are where power is applied to the GFCI. The LOAD terminals, though, are interesting -- they are effectively a third receptacle on the back of the GFCI, only implemented using screw terminals or backstabs ...


1

You're overloading the contactor. 7500 watts at 240 volts is 30+ amps, and the contactor you're using is rated for 22 amps. You have three choices: Get a different contactor. Follow the manufacturer instructions to change the wattage of the heater to 5000 watts or less. Use the internal thermostat of the heater.


1

There is more to it that you may not realize. By using manual switching, you inherently prevent even the remotest possibility of back-feeding the utility grid with your solar power. It is not physically capable of being connected to both systems simultaneously. As soon as you "automate" this, you introduce the possibility that something could fail in an ...


1

The instructions say the lamp and power block are a "matched set". The cord between them does not have a plug, and mustn't be cut, altered or extended. Considering how little IKEA says generally, and how much they say on this particular topic, it's clearly important. That makes sense: It's preferable to drive LEDs in "constant current" mode, and as a ...


1

The cycle timer you linked to seems to require 24 VDC. The thermostat will be fed with 24 VAC. Do not use that cycle timer! You can wire a cycle timer just like a thermostat, in parallel to the existing thermostat. You can wire it near your furnace if that's more convenient; it will just connect the two conductors to call for heat at the set intervals, ...


Only top voted, non community-wiki answers of a minimum length are eligible