Extra wire on MC240 GFCI

[scott451]

That's what I was hoping it might be for, but I see nothing in the spec sheet regarding it. Do you know what sort of control stimulus you apply to this line in order to call for the contact closure? If I remember right (I don't have the gfci in front of me right now) the unit has 2 line inputs and 2 line outputs. So I would sort of presume that the only natural thing to expect would be that applying ground to the red control might close the relay? That would be a pretty simple way for the device to work, as it would just require a 120V relay coil inside.

Do you know Scott?

Yes. I do. :smile:
There's nothing in the spec sheet because I believe this GFI was a custom version for Tesla. I believe that they separated out one of the power leads to the GFI control circuitry. This way they could turn the GFI on/off.

My first mc240 went bad a few months after I got my roadster. The red wire connects to an expensive Solid state relay (actually it's a optically connected triac). Mine smoked for whatever reason, so I just connected the red wire to one of the L1 or L2 pins. It may be a specific L1 or L2 based on how the GFI is wired. I would try the Lx that is red. IIRC the control voltage is 240V not 120V. I believe this is because the MC240 has no neutral pin so the only voltage you can get is 240V. Connecting a load between Hot and ground to get 120V would be a violation of NEC code.

 

[btown]

My first mc240 went bad a few months after I got my roadster. The red wire connects to an expensive Solid state relay (actually it's a optically connected triac). Mine smoked for whatever reason, so I just connected the red wire to one of the L1 or L2 pins. It may be a specific L1 or L2 based on how the GFI is wired. I would try the Lx that is red. IIRC the control voltage is 240V not 120V. I believe this is because the MC240 has no neutral pin so the only voltage you can get is 240V. Connecting a load between Hot and ground to get 120V would be a violation of NEC code.

Thanks Scott! So I'm assuming that best guesses are connecting the red wire to the wrong leg won't cause damage (ie. it just won't work). I'll give the red L1/L2 a try first and see if the relay pulls in.