Quick Question

Discussion in 'General Electronics Chat' started by mercury049, May 20, 2014.

  1. mercury049

    Thread Starter New Member

    May 20, 2014
    I have a 12V DC solar panel. It has a red and black wire.
    I have a 12V DC water pump.

    I want to put a switch between them.

    I don't understand phases or poles. When I look at switches, I see some with 2 leads, 3 leads, even 6 leads. Which one do I need? How do I hook it up?

  2. crutschow


    Mar 14, 2008
    The number of leads depends upon the number of poles (individual switch contacts) in the switch. You just need a single-pole single-throw (SPST) switch. You connect one of the switch leads to the red wire on the solar panel and one to the (red or positive) wire on the pump (which connects the switch in series with the circuit). Connect the black wire from the panel and the (negative) black wire from the pump together.
  3. ErnieM

    AAC Fanatic!

    Apr 24, 2011
    Hi mercury, welcome to the forums!

    Do be aware that pumps can be a problem for solar panels. A pump can draw a lot of current just to start up, then less as it runs along. That current surge can essentially short out the panel so the max current but minimal voltage goes to the pump, so the pump never runs. It isn't necessarily destructive, may just heats the pump up some, but it never pumps.

    Try your set up (even without the switch) and see if it works for you. If not, come one back and maybe someone will have a suggestion. (I saw one circuit on the web to handle this but I was not impressed with its design.)
    absf likes this.