Do I need to use a diode with the following setup ? What i want to do is activate a relay which then closes the positive side of a nema 5-15 portable receptacle and allows electricity to flow. When a switch is pressed . My aim is to avoid having to come into contact with the AC and use relay do it .

The receptacle I'm using is similar to the leviton Snap-In Single Receptacle Outlet Black 1374-1. My setup consists of using a 12 volt battery to drive an Inverter and then using the Leviton 1374-1 as as the receptacle.

I want to use the following wireless relay to act as the AC switch : OrangeTag Wireless relay . This will be used between the Leviton 1374-1 and the inverter . I've read about issues concerning relays damaging connected devices due to voltage spikes when the power source is removed and want to know if I need a diode to protect against this issue ?
if so where do I connect the diode on the relay ? The diagrams Ive seen appear to to connect the diode across the pos/ neg points of the relay which in my mind means a short circuit What am I missing ?

  • 1
    \$\begingroup\$ How are you energizing the relay coil? \$\endgroup\$ Jan 7, 2016 at 22:52
  • 5
    \$\begingroup\$ Ditto and draw a circuit. \$\endgroup\$
    – Andy aka
    Jan 7, 2016 at 23:08
  • \$\begingroup\$ Ditto and draw a circuit. \$\endgroup\$
    – EM Fields
    Jan 7, 2016 at 23:36

1 Answer 1


The damage you are thinking of is due to the voltage spike caused by the inductance of the relay coil when it is turned off (V=L*dI/dt). Since the relays are part of a complete package and the coils are controlled by a wireless receiver, that issue does not apply to you. You can even see one of the protective diodes in the picture of the relay module, it's the little horizontal black cylinder with silver at one end, between the capacitors (big silver-topped cylinders) and relays (blue boxes).

However, I don't think that relay module is appropriate for your purposes because it is labelled as "momentary", which means the relay (and therefore your receptacle) will be on only while you hold down the radio button.

You could, however, use the momentary relays to turn an additional latching relay on and off. I'll leave you to google up schematics for doing a latching relay.

  • \$\begingroup\$ Thanks Williams thats the answer i was looking for. The board ships with 3 swappable ICs. They are latching, momentary sustained. I use sustained mode. The relay is controlled by 12 v. Ive dismantled the inverter and taken the positive AC out cable joined it to one end of the relay. Ive then taken another cable joined it to the other end of the relay and connected it to a cable on the Leviton 1374-1. When i press the wireless button i'm able to turn off / on power to to the Leviton 1374-1. \$\endgroup\$ Jan 8, 2016 at 4:29
  • \$\begingroup\$ @AlfredAppiah If that's the answer you were looking for, you should mark it as accepted. \$\endgroup\$
    – tcrosley
    Jan 8, 2016 at 6:46
  • \$\begingroup\$ how do i mark an answer as accepted ? select the "Answer your question " link ? \$\endgroup\$ Jan 8, 2016 at 7:42

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