I just purchased the Honeywell wifi thermostat but my existing thermostat does not have a C wire. So the instructions given suggest using the G wire as the C wire and at the furnace to move the G wire to the C terminal. The problem is that my C terminal already has 2 other wires there, is it okay to add another? Is it okay for those wires to touch? They also suggested to build a jumper using 18 gauge copper wire from the Y terminal to the G terminal.
There's no problem with those wires touching. However, screw terminals are commonly only rated for one or two wires to terminate at them. If you're adding a third, it might be time to use a "pigtail".
Creating a pigtail
- Remove the wires from the screw terminal.
- Combine the two wires that previously were under the screw terminal, with the wire you're adding, and a short bit of scrap wire of the same or larger (smaller gauge) size using a twist-on wire connector (or other approved means).
- Attach the short bit of wire (pigtail) to the screw terminal.