Is it ok to leave relay module permanently connected to mains power?

Hi All

Hopefully a fairly straight forward question.

Is it ok to leave an ELEGOO Relay Module 4 Channel relay permanently connected to two mains lights and a horn? This is in a club house which is only occupied a couple of times per week.

Alternatively, do you have any suggestions about any kind of connectors I could safely use to attach the relays when they’re needed?

This is the module:

Thanks in advance.


Leave the mains installation untouched. Instead use a connector for attaching the module to the Arduino.

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I would use as simple Mains line cord like you get on a lamp.

Overall answer- Ensure your mains side wiring is secured and safe from accidental touches and shorts.

A fuse/RCD is always a good idea..

If you need to ask, it’s probably not a good starting point.
In some countries, the mains voltage will ruin your day, in lthers it can kill you - dead.

This. Hire an electrician.

Reading some of the other (very informative) posts I have to ask.

Where would you have connected the relays had the recommendation been to leave them connected all the time?

Personally I do not like these relays. There have been a number of posts where they have failed. And because I don't know who mfg them I wouldn't bet the farm on them being safe. I know they are made by a company who puts the name Songle on the relay but there is no historical record of their performance. A company like Allen Bradley, TE etc has industrial parts in the field by the millions. Folks know they are a quality part.

One also has to worry about what might happen if the relay failed and sent mains voltage to the Arduino and maybe the switch in your hand.

I also believe their UL mark is bogus based on missing some info required by UL.

Short answer. No.

My advice would be to contact a qualified electrician, familiar with the wiring regulations and relevant safety standards for electrical installations in your country (i'm assuming the UK). Especially as this thing is going to be used in a public space.

Also I would treat the specifications and certifications shown for that module as highly suspect.

What kind of loads are you talking about? e.g. If you're switching an inductive load, the inrush current could be seven times greater and would probably fry those relays.

Seriously, contact an electrician.

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