control high voltage & amps relays


My current project is to create a system capable of controlling a 220V 10A relay to physically switch power on/off on other hardware devices.

I just need to control 2 relays to turn a few devices on and off and hopefully be able to do so via a web interface (HTTP).

I'm totally new to Arduino and I'm not sure what to buy to get started.

I guess I'd have 2 alternatives.

1) a microcontroller board connected to my Linux HTTP server via USB. I would install Arduino software on my server, customize my HTTP server pages to use Arduino to communicate with the microcontroller. Then I'd connect 2 220V 10A relays to the microcontroller so that any user can turn them on/off from my custom web pages. What hardware and software would I need to do this? - 1 Arduino Uno ( - 1 USB cable - Arduino command line tools and Arduino software libraries to compile custom code on an X-less Linux system - where can I get 2 220-250V AC 10A relays that can be connected to the Arduino board?

2) same as in 1) except I'd need to add ethernet support to the microcontroller and a memory medium where I could store my HTTP server and scripts (or just a simple custom sockets program). What are my options? - Arduino Uno board with Ethernet Shield module ( orignore the Arduino Uno board and Ethernet Shield and use just one Arduino Ethernet microcontroller board ( - how can I store TCP/IP-accessible scripts on the board?

Option 2 would allow me to control power switching without having to use a server but I don't mind using just option 1.

Help/suggestions appreciated.



The 220V and 10A only mean the capacity of the switch contacts of the relay. You need to control the power of the coil from the arduino which will depend on the relay itself. Typically this could be 12V at 100mA. Therefore you will need a transistor to act as an interface between the arduino and the relay. You also need a diode across the coil.

Any electronics distribuitor will have dozens of relays that fit that description. Try Farnell, Mouser or Digikey.

You need a couple of these. {Third device down the page.}

At last! A 220VAC PowerSwitch Tail.

Whoo Hoo!

The way I read that photo is that it is a 120V device because that is the rating with the red dot next to it.

As you say. The implication though is that a 240V version exists and a trip to that linked page reveals that - yes, there is one!

It should be pretty bloomin' obvious - even to Mike - that the fact that there is a red dot in one option is because there is the alternate option, but just for his satisfaction: Happy now?

It should be pretty bloomin' obvious - even to Mike - that the fact that there is a red dot in one option is because there is the alternate option

No. Have you ever worked in industry? The only thing obvious is that a higher voltage option was planned. But whether it was implemented or if it was if it is in stock is another matter.

Ah, you haven't lost your touch. :D

Paul__B: Ah, you haven't lost your touch. :D


"Do via web interface" covered at

... if you are really, really sure you want to be turning something that powerful on when you aren't there to see, say, the towel draped over the radiant heater which had been turned off at the time the towel was draped on it.

For users above a certain level of expertise, many relevant points about working with more than 12v DC already covered above. For really new newbies, may I suggest...

When I switch 220 here in the states, I disconnect both lines because here in the states, they are both hot.

one leg to ground is 120VAC and that is what we use for lights and such.

this relay is a single pole, double throw.

Just want to make sure that this fits the OP's use,

why not use a single pole SSR ?