Arduino stoplight web server

Step 8 Wire the 120v part of the circuit

Now that you know the relays can be controlled, it is time to wire up the 120 volt part of the circuit.  If you printed out the board, this step is already done.  If you are doing it by hand, you have a few more wires to run.

Whenever possible, just poke the wires through the top like all the other components.

Because of the placement of the connections on the relays, and the tight squeeze, this is not always possible.  When this happens, run the wire to the nearest edge before routing over the top.  This will allow you to use the relays for strain relief and minimize the number of times you have to solder a wire directly to a component, plus help insure all the bits of the 120 volt part are as separated as possible in this small space.

I used a different color wire for the "hot" and control connections to be extra sure I didn't mix up the 120 volt parts with any of the control circuitry.

After this is done, you can use a multimeter to test connectivity between the hot screw and the screws for each of lamps.  There should be no continuity when the lamps are off, and a connection when they are turned on via the web interface that you tested earlier.  Do this testing thoroughly since a short here could be dangerous.

Comments

[buckmeisterq]

I used 20ga wire (or 22ga? it was solid wire rated for 300watts) for the 120v portion and nothing seems to be heating up or catching on fire yet. I didn't see a mention of a size for the 120v portion, but it seems like we're dealing with such a small amperage max (limited by the 5A fuse) that it should be OK.

[mkanoap]

According to http://www.powerstream.com/Wire_Size.htm, 22 gauge wire is appropriate for up to 7 amps, so that's why I specified that size.

20 is good for 11, so you are twice as good. :)