Two switches in one gangbox have a black wire connecting them together. Why?

Question

I am updating a couple of switches that are in the same gang box. All wires connecting to both of the switches are black. One switch has three back wires going into it and then on shared shorter black wire (see bottom of picture) connecting to the second switch. Curious why it is that way and is there another way to wire the two switches safely?

Answer 1

A typical light is on a circuit which powers many things. You know because they all go out when you switch the breaker off, which of course you do for any work :)

Switches take always-hot from the circuit, and connect (or not) to switched-hot to the lamp. Switches don't need neutral.

So it is normal for the switched-hot to be a solo wire on the switch that connects to nothing else. And for always-hot to hop from switch to switch making the rounds.

When wires need to be spliced to each other, there are many ways to do that. Many devices (switches or receptacles) provide a convenience splice block on them. Electrically it is no different than having pigtails joined in a wire nut, although it saves a wire nut if your boss counts your wire nuts at the end of every day.

Your switches have side screws and backstabs. Internally, the backstab is connected to the side screw closest to it. So 1 wire in backstab and 1 wire in the connected side-screw is an efficient (if hokey) way of connecting the 2 wires to each other and also to the switch.

Another is stripping the insulation 6" from the end of the wire and wrapping it in a U-hook around a side screw so the rest of the wire goes onward to somewhere else.

This could all be replaced with pigtails if you care.

I for one prefer to make my boxes intuitive by marking wires with tape or shrink tube to reflect their functionality.

• Native white or gray for neutral (this is mandatory)
• black for always-hot (since most wires are both these things)
• red for switched-hot for lamp #1
• blue for switched-hot for lamp #2
• yellow for switched-hot for lamp #3
• yellow in pairs for 3-way travelers
• blue for alt travelers, etc.

etc.

Answer 2

They are using the screw wrong instead of having a proper connection for the wires.

The wire connecting the two switches is a hot wire providing the power for both.

Switch screws should only have one wire under them, two(or bad case more) tends to make the connection not good.

The wires that use the push in connections plus the ones under the screw should use a wire connector(nut or wago) with one short wire to the screw. Push in connectors do seem to be a source of problems later on in life.

Have three wires at the bottom that are connected together(one in a push in). Add all three plus a short one to a connector(nut) and short one to the screw.

Top single wire should be removed from the push in and placed under the top screw.

Turn off the breaker and double check for power before touching.