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Tag: UK 2-Way Switch Wiring Diagram

Three-way switch wiring diagram with the LINE and the LOAD inside separate switch boxes. LINE power is delivered to the first switch by using a two conductor cable with a bare or green equipment grounding conductor. The LINE wire is connected to the "Common" terminal on the 3-way switch. A three conductor cable goes from one switch box to the other switch box. From the second switch box a two conductor LOAD cable goes to the light fixture or ceiling fan. The black LOAD wire is connected to the "Common" switch terminal and the two white neutral wires are simply joined together with a wirenut.

Three-Way Switch Wiring Diagrams

Dear Mr. Electrician: I need to see some three-way switch wiring diagrams.  I have two switches that control one light in my kitchen.  I am not sure if they are 3-way switches or 2-way light switches.  I find that one switch has to stay in the up position at all times just so the other switch will turn on the light.  How do I diagnose and fix this? Answer: This blog post has a few different three-way switch wiring diagrams and one 2-way diagram along with some good advice.  One diagram is above, the rest are below.  NOTE: Some text links below go to applicable products on Amazon.  As an Amazon Associate, I earn from qualifying purchases.    My three-way switch wiring diagrams are available as stickers from RedBubble.  As a RedBubble affiliate, I will earn a commission from each item purchased. Two-way electrical light switches and 3-way light switches are the same, they just have different names according to country.  One of your three-way switches may have broken down.   Shut off the electrical power for the circuit at the circuit breaker box.  Due to multiple wires being hot in this particular type of switch wiring it can be a little tricky for an amateur to diagnose which 3-way switch failed.  Assuming that the 3-way switches were wired correctly, I suggest that you change one switch.  If that doesn't fix it, then change the other one.  I usually take one wire off the old switch at a time and put it on the new switch then repeat with the other wires.  Please note the different color screw terminals.  It's a good idea to replace both switches at the same time as the other one could fail soon after. If the 3-way switches were not correctly wired, then you must be very careful to identify the LINE and LOAD wires BEFORE you disconnect the switches.   LINE is the power and LOAD goes to the light or other things controlled by the 3-ways. The LINE wire will be live (Hot) with electricity at all times regardless of the 3-way switch positions which makes it the easiest to identify.  Use a voltage tester with two leads or a pigtail light socket with an incandescent or halogen light bulb. Non-contact voltage testers may give you false readings due to the proximity of the wires on the switch.  It is best to remove the suspected hot wire from the screw terminal to test it with a non-contact voltage detector. Wear insulated electrical gloves when working with live electrical circuits. Click here for my blog post about working around your home safely. Do not remove all of the wires from the one three-way switch at once and then try and figure out what each wire is.  First thing is to take notice of the color of the screw terminals on the old switch.  One screw terminal will be a different color than the other two screw terminals and will be labeled "Common" (See photo below).  That screw should have either a LINE wire or a LOAD...