Is there a 4 x relay shield that is rated to switch 240 volts? Preferably with cutouts around the 240 volt areas?
I just bought the Arduino 4 x relay shield after the advert claimed it could switch 240 volts, but the packaging in the box says 48 volts maximum.
It sounds odd. 48 volts was a standard voltage on warehouse forklifters.
Please post a foto of the relay showing its markings.
Regarding the advert, You could claim a refund etc. Maybe they sent the wrong relay because the correct one was sold out? It has happend.
Recall that 240 VAC is NOT the peak voltage. You are dealing with 340 volts peak!
That shield documentation is ridiculous, there's not even datasheet available. The relay itself is rated for 125VAC. No idea how they ended up with number 48V, maybe some local hobby-electronics regulation.
Anyway, it's not power-relay. You need to look for third party shields like this:
That could be a DC rating, many relays are rated for different currents at different voltages with different loads. I suggest for the best results you get solid state relays with zero cross, that will keep noise down and you can drive them directly with the Arduino output. They are optically isolated. When I use them I place the solid state relays in an approved box the do the high voltage wiring etc in that box and use a small multi-conductor cable to go to the Arduino in another box from the relays. The following pictures may help. The relay shown is not the correct one for you but there are a lot of different ones in the same or similar package.
With those blue relays I wouldn’t put them anywhere near 240VAC.
as well as the switching voltage and current one has to consider the type of load being switched - see ac-utilization-categories-iec-60947 - a relay rated a 10amps resistive load may only be 2 or 3 amps for a Squirrel-cage induction motor
you need to check the device data sheet, e.g. the datasheet of solid-state-relay-20a-32vdc-din/dp shows
note ratings AC-51 (Non Inductive or Slightly inductive loads), AC-53A (Control of squirrel cage Induction motor on 8 hour duty with on load current) and AC-53B (Control of squirrel cage induction motors on intermittent duty)
I doubt it. A shield is close to the low voltage pars of the Arduino, which would make a shield potentially too dangerous.
Leo..
Does it have to be a shield?
although the Relay Shield V3.0 referenced in post 4 appears to be a very neat solution I tend to agree with @Wawa having 125V or 250V signals so close to a UNO is dangerous
also consider
I have used 4 channel relay modules such as Relay Module 4 Channel DC 5V with Optocoupler for UNO based prototypes
Thanks for all the replies, my project looks quite similar to horace's but without the WiFi modules. I'm using a block of blue relays, which have been switching away for 5 years or more now, with no problems. I was just looking for a way of tidying it up.
maybe worth trying the shield of post 4 to "tidy up" - if you do so let us know if it works
however, there is an old saying "if it not broke don't fix it"
