With just $6 and a tracking number you can get this 8 channel relay module in less than 30 working days.
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.
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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:
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.
Peter Oakes reviewed one here if you want to look inside:
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
can either come in 9v versions for their own RoboTXT controllers
or in 24v versions for use with the likes of the Siemens Simatic S7 1200 series PLC controllers
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
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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.
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
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.
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Farnell carries lots of optically isolated solid state relays that meet your specs:
here are a few of them:
michaelkellett is quite right about seperating the mains from the control side.
We have discussed electrical safety before on the site and there are no shortcuts.
The basic idea is to ensure that the low voltage control side and the mains are properly seperated.
The relay unit you have does at least have the board cut to increase the seperation distance where the relays moutn to the board, however I'm not sure if the pcb track sizes are up to the 10A rating.
On some versions the size is quite small and doesn't include a reinforcement wire to improve it.
We talked it about safety and the importance of the insulation and physical distance during the Forget Me Not challenge.
I suggested these since they are available to suit whatever mains outlet configuration the country has, and can be controlled by 433MHz RF.
Since then there is another cheaper WiFi and RF solution and they even have one that interfaces between the light socket and a lamp.
I believe someone has broken the coding to allow it to be used locally rather than their web server.
In short there are options but without the necessary approvals and safety inspections you could be creating a problem if there was an electrical event.
Whether that is an accidental contact or the worst a fire, there may be questions raised and possible insurance issues.
This is why I am watching these type of topics and columns here... i can't move on to create permanent smart home installation with inexpensive 5V or 12V relays... still looking for reliable solutions within my budget
If you got a raspberry PI 3, You could have Arduinos connected to Arduinos. And they could be controlled by the raspberry PI so it would be cheap. There could be hundreds of Arduinos connected to each other through the house connecting to the raspberry PI. Or just 2 connected to each other.
I think we are talking about controlling AC with safe and secure...
So if you want really safe and secure mains control, a consideration might new the new NFC programmable Timer Relay from Schneider Electric RENF22R2MMW | Multi Function NFC Time Delay Relay, Screw, 0.1 s → 100 h, 2CO, 2 Contacts, DPCO, 12 → 240 V ac/dc | Schne…
I could not find it on Newark site but I have already reviewed a prototype of this device and it is pretty cool. I now have 2 production units to play with
Based on the specifications the release voltage for its control input is <2.4V so should be controllable from Arduino. I will test this out in the next few days
anyway, it is a brand new unit on the market and certainly is for industrial use.
The other think I will mention is about the Industrial Shields units. They are CE certified and are for industrial use. There not for EVERY industrial application though for many of the reasons mentioned above.
Would you use them in a smelting application or other more extreme environment. No, not without additional protection in the form of cabinets etc.
I would entertain them though in a more normal environment like process control in a people populated factory ... production line control for instance, certainly for home automation where the environment is well controlled, and certainly for office automation.
If you want to have something in the more extreme industrial / temperature range installs then this is probably not for you. Otherwise this is a great set of nuits that are very open for your choice of software. I have examples running ModBus etc with no issues whatsoever. Not in an industrial setting but running well nevertheless.
NFC is _so good_ for configurations. I'm surprised it isn't used as much as it should be, everywhere!!
TI has a nice part that is in a hand-solder-friendly package, and easy to use, the RF430CL330H.
Never entered my mind to use NFC for touchless activation.
That gives me an idea for a demo device to show to some people being introduced to Arduino.
There are even more possibilities, like activation without taking the device out the package : )
(I've no idea if Peter's device does that, but technically it is feasible).
NXP has a part which can be NFC-configured without main device power being switched on.
It is a fantastic part but unfortunately Farnell doesn't stock it last time I checked.
The TI part mentioned above doesn't support that particular bit of functionality, but has the advantage of being easier to obtain. I've tried both, they are both awesome parts.
I'm building a new house, and I decided that I want microcontrollers to control my lighting. Now I have dimmers covered, with a 0-+10V system, but surprisingly I'm struggling a bit with the lights that should just be on or off. I figured it should be doable with a relatively cheap array of relays connected to an Arduino. I'm not going to get my hands dirty, my electrician is (which is, I should say, a good idea). He insists on the following standard for the relays:
- CE certification.
- at least 240 VAC
- at least 10A
- DIN Rail mountable
I'm guessing I could satisfy the last requirement with a PCB in something like this: http://cpc.farnell.com/pulse/acc-case-m/flightcase-universal-medium/dp/DP31699
I have not yet found a product, that matches all of the top three though: I found something in various shops that has 250 VAC @ 10A, but no visible CE mark, and I found one on hobbyking http://hobbyking.com/hobbyking/store/__26921__Arduino_6_Channel_Relay_Module.html that had a CE mark, but could only do 240VAC @ 7A. I'd like something like that, with 6-8 channels would be nice.
It would be nice if the electrician could order all the products from Farnell, since they have a Norwegian office and I have used them for some other projects. Any pointers?
Message was edited by: Matt Collinge. Updated CPC link.