I have the above 4ch 30A relay. I am using it with nodemcu plugged into the expansion board from the second link. The expansion takes 12v and produces regulated 5v for nodemcu. If I plug in 5v to the relay I can only get 1 relay to work. So I used 12v which made all the relay to work. But now slowly one of the relays, have stopped working. Though the led is turning on faintly, relay is not switching.
Can someone guide me on the required power supply. Though the relays says 5v on top why do they require 12v to work? And within 7 days of operation why is one of the relay faulting?
The links goes to sale sites. Links to their datasheets would be useful.
Likely the 12 to 5 volt converter doesn't provide enough current for the relays.
Feeding 12 volt to a 5 volt coil is murder....
The following specification is VERY concerning: "Using high-power relay, the maximum control load DC 30V 30A / AC 250V 30A;
For both the AC and the DC rating to be at 30 amps is close to being impossible. The problem being the contact arcing when they are opened. AC will self-extinguish the arc, while the DC will sustain it and burn up the contacts.
What are you switching with the relays ?
I’d agree the spec looks fishy and the relays , or terminals don’t look good enough for that sort of current .
Water pumps... They draw water from well and push it to a overhead tank
What are the power requirements for each pump? Water pumps take a LOT of current just to get the water moving. I am betting your relay contacts are burning due to overload.
they were previously tied up to normal 15A switch and they are still running fine for about 3-4 years. Hence I got the one with 30A relay.
Hi,
Can you please post a picture of your relay unit, so we can see what is written on the top of the relays?
The "spec" says.
" Industrial Control (4-Channel 5V)"
Well industrial control is 24V and the relay unit in the image on the Amazon page shows 24V relays.
This may be a bit better specwise;
https://rees52.com/general-purpose-relay-module/2333-4-channel-dc-24v-relay-module-highlow-level-triggering-optocoupler-isolation-for-plc-automation-control-rs1868
It seems REES52 specify the unit as;
- Supply Voltage: DC 5V / 12V / 24V
Can you please post circuit diagram of your project?
Include ALL power supplies, component names and pin labels.
Thanks.. Tom... 
And your switch is UL listed to carry that current and voltage with out a problem. Your relays have tiny half/ball contacts with very little contact surface. Get real industrial relays for your project and control them from the Arduino with mosfets and your project will run for years.
Can you post example project links please?
The picture shows 12V relay coils, I assume the 2 red terminals are for the 12V, the right end of terminal strip has "COM" and 4 inputs and assume the "IN" voltage = 5V. Need schematic.
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