Arduino relays for lighting

Your electrician is right in terms of good practice and it may well be that local laws require the parts to comply with his suggestions. I expect you would like your house to last at least 25 years before rewiring and certainly never to catch fire. $6 for 8 relays will NOT achieve this.

Farnell 186302 in a 1340952 socket is the kind of thing I would use. Arduino isn't the right kind of thing for this - I think you should go for industrial standard parts and practice which would suggest 24V DC relay coils.

The mains stuff should be in an approved enclosure and wired according to local regulations using approved wire. Once you get out of the mains box into the low voltage control stuff it's probably OK to use your own controller built to hobby standards but in the UK you would find it impossible to sell the house (the solicitors would insist on disclosing how it was done and the purchaser wouldn't be able to raise a mortgage on it.)

If I were you I would grit my teeth and fork out for a proper approved controller which has all this kind of stuff sorted and offers a WiFi or Bluetooth interface (or better still Ethernet) for you to play with. You'll need to search around for this kind of gear - most of the quickly googled people I found were installer/designers who would charge you an arm and  a leg.

Do, please, watch out for those local regulations - here in the UK people have had to knock down buildings due to non-compliance with regulations during construction - it may be better in Norway but I wouldn't bet on it.

MK

Michael Kellett wrote:

 

...Arduino isn't the right kind of thing for this - I think you should go for industrial standard parts and practice which would suggest 24V DC relay coils...

 

 

There are these Arduino controllers wrapped in an industrial style DIN rail type enclosure offering 24Vdc connectivity:

Industrial Shields – Industrial PLC Controller based on Arduino

Michael Kellett wrote:

 

...Arduino isn't the right kind of thing for this - I think you should go for industrial standard parts and practice which would suggest 24V DC relay coils...

 

 

There are these Arduino controllers wrapped in an industrial style DIN rail type enclosure offering 24Vdc connectivity:

Industrial Shields – Industrial PLC Controller based on Arduino

Those look quite nice - have you used them (or seen inside.)

I didn't suggest standard PLCs because they are so un-Arduino like to programme but these things might be a nice compromise in some places.

MK

Peter Oakes reviewed one here if you want to look inside:

https://www.youtube.com/watch?v=GpiHQZAF4n0

I've not used one as yet - first spotted them when I was looking at different types of automation control for educational purposes. The likes of the Fischertechnik industrial automation kits

fischertechnik GmbH - Industry

can either come in 9v versions for their own RoboTXT controllers

fischertechnik GmbH - ROBOTICS - ROBOTICS TXT Controller

or in 24v versions for use with the likes of the Siemens Simatic S7 1200 series PLC controllers

Compact automation solutions - SIMATIC S7-1200 - PLCs - Siemens

Needless to say, my next thought was if there was an Arduino based PLC solution...

The PLC that Dave mentioned (That  I reviewed) is an Arduino based industrial PLC and is CE rated 240V if you get the relay version. and then you get to program it the way you want, it will mount on a DIN rail and it will handle the mains voltages

For lighting I don't think you will need 10 Amps per circuit, certainly not at 240V, that's a lot of lights on one circuit. but this PLC should do the job for you right out of the box (Just add code), Oh and you can get them with network interfaces too if you want. they all come with RS485 irrespective so easy to hook into other control systems

I just skimmed your review on YouTube - and was quite surprised that you seemed to like it so much.

I had dumped them into the "not worth considering"  box after looking at the spec -

They quote max and min operating voltages as 11.4 - 25.4V - for an industrial level nominal 24V device I expect much more - I design 24V industrial electronics to work with no de-rating at 30V and withstand 40V pulses. (The first standard PLC I looked at was a Siemens one which claims 28.8V.)

The ambient temperature range is far to low at 0-45C, for domestic lighting in Northern Europe it is not acceptable for it to fail if the central heating dies so I would look for -20 in the OP's application but for general industrial use this might not be essential. However DIN rail control electronics is often in cabinets with a load of other things so I would be looking for a max operating temperature of at least 60C (I would like higher but this could get expensive.) (The Siemens PLC is rated -20 to +60 C).

So my conclusion was that these "Industrial Shields" are just hobby electronics dressed up a bit - OK perhaps for a quick lab based test rig but no ready for the real world.

It would be nice to know if anyone has actually used them in a tough environment alongside PLCs from the established suppliers.

MK

Perhaps one interesting thing to note though is that the Atmel ATmega32U4 microcontroller was was used in the Arduino Leonardo board appears to be rated for a temperature range of between -40 to +85, so isn't necessarily the limiting factor from a harsh environment perspective.

(I see that the same microcontroller is being used again in the newer Arduino 'Industrial 101' controller

Arduino INDUSTRIAL 101  )

I guess though that some of the supporting electronics on the Arduino boards could be an issue - the aluminium electrolytic caps probably are only rated at up to around 2,000 hours lifetime when operated at +85C ? e.g.

EEE-FK1E470AP PANASONIC ELECTRONIC COMPONENTS, ALUMINUM ELECTROLYTIC CAPACITOR, 47UF, 25V, 20%, SMD, FULL REEL | Farnell…