How do you wire an LED light to be control by 3 swithes

Thread Starter

jwbutler123

Joined Jul 24, 2017
5
I'm new to DC electronics and am remodeling an RV and want to control the light over the dinette with 3 different switches. Is there a wiring diagram somewhere I could look at. I'm assuming I'd have to use SPTT switches but have no idea what it would look like.
 

Tonyr1084

Joined Sep 24, 2015
7,829
All good answers before mine. Here's a diagram of just how a four way configuration works:

In the upper section you see the simpler 3 way switch configuration. The main line comes into the common (C) connection on the switch. L1 is then connected to the other L1 and L2 is connected to the other L2. The second switch's "C" terminal is connected to the lamp. The white (neutral) wire isn't connected to any of the switches. You can turn the light on from one location and turn it off from the other.

In the lower section there are two diagrams labeled "UP" and "DOWN". Obviously this is relative to the position you install the switch, but the diagram showing the UP position shows that L1 is connected to L4 and at the same time L3 is connected to L2. Since I didn't have a 4 way switch in hand when I made this drawing I chose to label (at random) L1 through L4. The point is that in one position power switches from one line to the other and in the down position power passes from L1 to L2, as does power on L3 and L4. Hopefully this drawing will clarify just how a 4 way switch works. In fact, in this configuration you can have as many 4 way switches you want in the middle, as long as the first and last are simple 3 way switches.

Switches.png
 

Thread Starter

jwbutler123

Joined Jul 24, 2017
5
All great information, thanks. Based on the diagrams I have one more question - It appears that switches in DC are wired the same way they are in AC. Is this assumption correct?
 

Tonyr1084

Joined Sep 24, 2015
7,829
switches in DC are wired the same way they are in AC. Is this assumption correct?
Essentially, yes. In this case you're providing power via L1 or L2. And in the case of the 4 way switch - well, it's the same thing.

Keep in mind that these switches (for homes) are designed to handle 120 VAC and currents of probably 15 amps. I'm sure you can find them capable of handling 20 amps, but these are the typical ratings. But what you need to understand is that using such a high powered switch to switch very small currents can lead to switch failure over a short time. Exactly how short - I can't say. But switch contacts need sufficient current to clean away the carbon that can build up from arc flashing (when the contacts close).

Since you state that you're going to be lighting an RV, I'd guess that you're probably switching sufficient current to keep the switch healthy for years to come.
 
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