Hi @proxybox 

Connect one lead of your voltmeter to ground, then check each lead(starting with the HS200) and verify the correct voltage.

Make sure you include the neutral, my guess is that you have neutral(0v) and line(120v) swapped.

I did check from ground to lead. At a test bench. try powering up the HS210 or for that matter the HS200 as well. You'll see without any load on the outputs that each will have about 110V.

The neutral is not the issue because it is connected directly to the line neutral.

@proxybox Hello,

I had questions about both the HS200 and HS210 switches so l opened the HS210 and drew a partial schematic/block diagram.

There is a SPDT (single pole double throw) relay on the pcb. The 2 "Traveler'' connections each have a diode bridge that one or the other can provide power to the relay control board thru either of the terminals.  So when power comes from "Load/Line'' contact it feeds one of the traveler contacts thru the relay, no matter which position the relay is in.

The N (neutral)wire connects to both the 2 diode bridge the circuit. 

In all 3 way switch circuits, the 120V "'Black'' is comming "To''  the ''Line'' terminal from the breaker, or to one of the ''Travelers'' from the switch that has the 120V feed.

The ''traveler'' wires are either Red and Black or a Black and White with black tape on the white to signify ''hot''

I assume that the HS 200 uses the same double bridge power technique is used and thus it does not matter which black wire is hot. 

The drawing is semi schematic and semi block diagram. I found no one has posted anything like this.

@Camano7 Thanks. I never figured this out but my fan works. One oddity is that the switch shows ON when the fan is OFF and OFF when the fan is ON. I flipped the load and line but still behaves the same. I'm trying to use it as a SPDT but this is not wha thtey intended it to be used for. 

@proxybox That is typical to all lit switches, even the old neon type. If you want it off, try moving the wire to the other traveler screw. Since its a spdt relay, the light is ''ON'' when the relay is off. HS210 simply switched the Load/Line back and forth from one Traveler contact to the other. 

SPDT =  Single Pole Double Throw

@Camano7 any idea why all I can get from my light is a quick switch off? You seem to know what you are talking about....

I've tried connecting all three wires to all three screws and all I get when I turn the light on is a flash and then it turns off. Sometimes it renders the other switch useless.

Ideas?

Samantha

@proxybox Try reversing the 2 ''Traveler'' leads not Power/Load &Traveler. HS210 light is lit when power is on "Traveler 1''

@Camano7 I have been posting this thinking TP-Link would offer some advice or real drawings. 

Here are 2 updated drawings. With no powre applied; N.O = Normal Open contact N.C = Normal Closed contact. 

@Camano7 Oops. I meant reversing the traveler leads. Yes, I tried that but it still behaves the same.