Is it safe to use a SPDT relay as a SPST relay (110v)?

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Greetings. I’m a beginner and I’m trying to build a very simple arduino-controlled switched 110v outlet. I thought I could use the JZC-11F relay (https://www.sparkfun.com/products/100) that comes with the SparkFun kit, but I now realize that it is a SPDT relay. I only want the outlet to turn on and off.

I understand that this relay has a COM (common), normally-closed (NC) pin and a normally-open (NO) pin. My intention was to wire up the line (black wire) in an old extension cord to the COM and NO pins. When I apply voltage to the relay it closes and the outlet (female) end of the extension cord turns on. Its about as simple a project as you could imagine, but it does involve 110v.

Since I am not connecting the NC pin, is it safe to just put electrical tape around it? Or can I just snip the pin off with wire cutters? Or is there another option? Or is none of this safe, and should I go out and buy a SPST relay?

I’m using the following two articles as reference:

https://www.sparkfun.com/tutorials/119

http://www.glacialwanderer.com/hobbyrobotics/?p=9

Any advice would be appreciated.

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Yes, it is fine to use the SPDT relay instead of the SPST one. Just make sure, as you pointed out, to insulate the NC pin (and NO and COM as well).

That relay has a 5A max rating; make sure you don’t try switching something over 5A (600W at 120V, 1200W at 240V)

/mike

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rickpasetto:
Greetings. I’m a beginner and I’m trying to build a very simple arduino-controlled switched 110v outlet. I thought I could use the JZC-11F relay (https://www.sparkfun.com/products/100) that comes with the SparkFun kit, but I now realize that it is a SPDT relay. I only want the outlet to turn on and off.

I understand that this relay has a COM (common), normally-closed (NC) pin and a normally-open (NO) pin. My intention was to wire up the line (black wire) in an old extension cord to the COM and NO pins. When I apply voltage to the relay it closes and the outlet (female) end of the extension cord turns on. Its about as simple a project as you could imagine, but it does involve 110v.

Since I am not connecting the NC pin, is it safe to just put electrical tape around it? Or can I just snip the pin off with wire cutters? Or is there another option? Or is none of this safe, and should I go out and buy a SPST relay?

I’m using the following two articles as reference:

https://www.sparkfun.com/tutorials/119

http://www.glacialwanderer.com/hobbyrobotics/?p=9

Any advice would be appreciated.

You could connect the hot wire from the AC power source to the NO pin, rather than common. And connect the hot wire going to the load to the common pin. This way there won't be 110v on the NC pin when the relay isn't switched. It would be best to use heat-shrink tubing (rather than tape) on the pins (after wires are soldered) to protect you from power line voltages. I would use HS tubing on all unused pins, too.