One of the two wires in the lamp cord is neutral, the other is line. You can get an inexpensive tester that will indicate which of those two is hot. Is the plug on the lamp cord polarized, i.e. one blade of the two in the plug is wider than the other? This link provides some good info on that subject.
Hmmm, maybe you aren’t in the US, in which case this info is of no use to you. However, to complete a circuit, there must be a source of current (hot) and a return path for current (usually neutral.) I don’t know what that standard is for wiring in the UK and EU.
Hmm. Well I can hear the relay click when I trigger it, the lights just don’t come on. I guess I’ll try reversing the power leads.
Word of warning on the Shelly power if you have live and neutral reversed on the Shelly feed it will blow the Shelly, I know I made the dumb mistake on one of mine, it seemed to be ok then overloaded and bang.
Well flipping the two wires had no change. The Shelly still powers up and the relay fires but the lights will not come on. I think I need to jump to one of the other connectors.
Need someone with more electrical knowledge than me.
Can you share a picture of the Shelly and how you have it wired?
I’m in the uk so on 240v but have a test rig with a light and led bulb running from a 3 core cable, not using ground, to a standard uk 3 pin plug, the Shelly is also connected to a standard uk light switch but that shouldn’t make any difference for just controlling a bulb/fixture.
Yes, especially when playing with domestic AC!!
Yes please get someone who knows what they are doing.
The Shelly will be fine as ac backwards will not hurt the device, it is alternating current. Putting the input to the output terminals would be different. Hhowever if you treat neutral and live as the same you can kill someone as often a switch only removes the live wire and if you have them backwards when the switch is off the device still is live and can kill.
If u have only two wires it can be wired what I call
Active and switched active. The neutral can be missing from the switch location. The old wires can be used to pull new ones through.
Also be careful of the programming pins on the Shelley I hear they carry mains voltage so need to be isolated before you program them.
Guys - thanks for your concerns but I’m not a complete novice/idiot with this…I know this is something different (not having a neutral in the fixture) so that’s why I reached out.
I have rewired/replaced many switches, plugs, receptacles so this is not my first rodeo - again thank you for the concern.
Here’s how I tried to wire this up…
Any suggestions would be appreciated.
Does the lamp have a manual switch you plan to use? If so you can use this as a guide just modify the neutral and wire nut the it to the neutral from the light.
How about this video ( sorry only in German).
It might help us helping you if you would post what kind of wiring you have ( picture or…)
From the plug image you show, I am guessing you are in the US or possibly Canada. The US convention for wiring is WHITE = NEUTRAL, BLACK = LINE (HOT.) If the plug you have is polarized, the wider blade is NEUTRAL and the other, narrower blade is LINE. As noted in a previous comment, you really should confirm that you are switching LINE to the bulb in your lamp so there is only LINE voltage at the bulb when the lamp is switched ON. LINE voltage should be applied to the bottom contact of the bulb. The threaded base part of the bulb should be connected to NEUTRAL and is always connected from the plug to the bulb’s threaded base. In the preceding post, the NEUTRAL connection is not shown in @H102’s diagram. Other than that omission, @H102’s diagram is correct. Also, note that the Shelly1’s jumper must be configured for 100-240VAC.
I mentioned previously that you can purchase a simple, non-contact voltage sensor with which you can confirm that you have correctly identified which conductor is LINE (HOT) and which is NEUTRAL. I highly recommend that you get yourself one. This is not a recommendation, but such a sensor is this one available from Home Depot:
No manual switch currently, but could always add one. That’s the way I typically wire up my Shelly’s.
In your pic the blue wire needs to be removed from I and connected to the red. The black wire also needs to be connected to where the blue is now ( the I). A short piece of wire and two wire nuts should be all you need.
Does that make sense? I can try to draw it out if my wording is not understandable.
Hi Scott -
Yes I am in the US and no the plug is not polarized. I have a non-contact voltage stick and have tried wiring both ways and still the relay works, but the lights do not come on. I take the shelly off, hook the power leads directly to the bulbs and they light up.
It’s something in the relay connection inside the shelly that needs to be addressed.
The shelly is correctly setup for 120vac.
Here’s my poor excuse of a picture. Wire nut where my red links to yours and do the same for the black.
As shown in your first diagram:
There is only a normally open relay contact connected to your bulb, i.e., NEUTRAL is not connected to the bulb’s threaded base and there is no source of power (LINE) to the bulb’s bottom contact.
In @H102’s first diagram, ignore the two connections (shown in BLACK) from the switch to SW on the Shelly1 and the other switch connection to LINE. The relay contact connections are shown correctly in that diagram. Simply add a another wire to connect NEUTRAL to the threaded part of the bulb socket on the lamp. That will provide a return path for when the Shelly1’s relay is activated, which connects the Shelly1’s I to its O terminal, which connects the source of LINE voltage to the button tip of your bulb.
[Update] @H102’s second diagram shows exactly what I have tried to describe here.
I’m not using the SW in the pic. The Shelly is powered by the connection to L and N. Then you need to have the power that goes thru the relay, the I connection, and out the O (green wire) to the bulb. From the bulb you need a return path to the neutral, the red wire in this case.
EDIT: Just to be clear, in the pic I posted, wire nut the red wires together where they meet up. Wire nut the black wires together where they meet up. Doing this you will have power to the Shelly and to the bulb when the relay closes. There is nothing connected to SW on the switch.
Thank you to everyone for joining the conversation and your suggestions. @H102 your Picasso led me to the promised land!!!
This is what I really love about this community.
Thanks again for all of the input.
I have exactly the same problem with my wiring.
In your setup, is Shelly overriding the physical switch? What I mean is, do you keep the physical switch on at all times and shelly controls the light bulb?
KidSquid is not using the manual switch, it’s bypassed, but you can and a switch if you choose. Adding a switch and using the “SW” connection on the shelly allows you to control the light both ways.
You will only need to keep the switch on at all times if using the switch to feed power to shelly. Normally you would want power from the breaker to supply both the shelly and the switch. See illustration in post 11. The lighting bolt on bottom right would be power from breaker. Notice it feeds the “I” (input for shelly to operate bulb) and “L” (used to give power to shelly device) terminals and to one side of manual switch. The other side of manual switch is connected to “SW” of shelly. When you turn on manual switch shelly gets input at “SW” terminal and closes the contacts between “I” and “O” (internal set of contacts).
Hope this helps.