I am trying to install (2) Lutron Caseta Wireless Switches to replace two legacy light switches. This is my first attempt at replacing a light switch. When looking inside, I am a bit confused on the wiring configuration:
-Why are there four white wires that are just joined together? Do they serve a purpose?
-Why is only one switch grounded?
-Why is there a connection from one switch direct to the other (capped with a yellow connector in this image)
Electrical – Confused on this wire config
electricallightingswitchwiring
Related Solutions
Plasterboard Work
It is often possible to run a new cable between a fixture and a switch without tearing up large sections of drywall.
If you can visualize the wire going up the wall from the switch and then from the corner of the wall/ceiling to the fixture, you may be able to snake a new wire.
Cut a small hole in the ceiling in in the plasterboard immediately above the switch.
The issue will be whether the hole in the ceiling allows you a straight run to the fixture box (along or between a ceiling rafters). If not, you nay need to cut more small holes where the cable would have to cross a joist/rafter.
If it is a clear run, you may be able to run a cable from the ceiling hole to the fixture box. Then you can cut a small hole in the wall immediately below the first hole.
You also need to be able to drill through or notch the framing (without seriously compromising a load bearing wall) to allow a cable to pass through. If this is feasible, you can drop a cable down to the switch box, thread the other end through the hole or notch in the framing, and extend it to the fixture box. If you are notching or if you are drilling at less than 1.5 inches in, you need to put a special metal plate over that spot to protect the cable.
Later you can patch the small cutouts, tape over and paint.
Wiring
You can continue to use the existing cable to power one circuit and use a 14-2 cable to provide the hot leads for the other two circuits (they will all use the neutral already on the circuit. Since both wires in the new cable will be hot leads for a circuit, the white wire needs to be marked at the switch and fixture to show that it is hot.
You can find three switch units that fit a single gang box, or expand the switch box to double gang.
Managed to solve this myself with a live wire detector:
I believe the red/black on the far right of the diagram are wired incorrectly, as the black is live and the red neutral.
I believe this set up is described here, which states that it's not recommended for new installations for many reasons, but can be found in old homes.
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Best Answer
The whites in the back of the box are very important. They are neutral, and you wouldn't have a circuit without them. Also it's rather fortunate they are there, because a good quality smart switch will require them.
On both switches, you have 2 wires going to a single screw terminal. This is nothing but a lazy shortcut in wiring. Those multiple wires could be replaced by a pigtail, in which case the wiring would be easier to understand. It looks like that hoppy wire is the "always hot" wire, and is commonly** color coded black, which it happens to be. The solo black wires are switched-hots going up to the lights, and they are commonly** color coded red, and I'd mark them with red tape. I'dThis will make it even easier to understand.
Most people, even freshmen like yourself, don't need equipment safety ground explained to them. The only thing you might need to know is when ground has insulation, it is green, or green/yellow stripe.
** that is common practice. The law only specifies colors for ground and neutral (white or gray). Legally a hot can be any other color. In this wiring, the switched-hot is black because they are using pre-made cables and don't have a choice for color. That's what tape is for.