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Electrical Question from Aneta about Wiring Symbols

By Dave Rongey - Summary:

I am trying to install a new digital pool timer. The schematic on the backside has a connection terminal under each of these symbols/letters NO, NC, COMM and an M with ~ under it

Electrical Question from Aneta about Wiring Symbols

Received from Aneta a Handywoman in Harrietta Ca

Question: I am trying to install a new digital pool timer. The schematic on the backside has a connection terminal under each of these symbols/letters NO, NC, COMM and an M with ~ under it (has 2 terminals). I know the COMM is common or HOT but I don’t know the others. Can anyone help? I have 4 wires and 5 connection terminals. This Innovation Model ET-2 timer is an exact replacement of the old timer. I just purchased the house and this timer was disconnected because it no longer worked so they connected the hot wire to the pump and would flip the breaker to turn on.

Dave’s Reply:
Thanks for your electrical question.
Aneta – The timer you have is used to control a function of the pool device. To do this the timer is basically a clock that is set to turn your pool equipment on or off at a specified time. This is accomplished by a relay which is identified by the letters and symbols.
Here is a brief explanation of what you are describing here – Listed below:
Comm = The Line or Incoming Hot
NO = Normally Open (or OFF)
NC = Normally Closed (or ON)
M is the symbol for the Time Clock Motor
~ is the symbol for AC Power (from my perspective, the voltage us unknown)
Because you are dealing with Pool Equipment, I would strongly advise you to hire a Licensed Electrician to do this for you and make sure that the proper GFCI protection and grounding is in place.
Electricity and Pool Equipment is no place for a novice – Sorry, but it’s for Safety!

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One Response to “Electrical Question from Aneta about Wiring Symbols”
  1. Dave Beckman says:

    The terminals are marked 1 – 5.
    Terminal #1 is 120 volt AC power and there is usually a black wire with a .250 blue spade connector that has a 2nd black wire with blue connector attached to it. These wires are 120 volt and go to terminals 1 & 3. (It doesn’t really matter which goes where as it is a jumper that supplies power to these 2 terminals. Terminal 3 being the common terminal of the clocks internal relay. Terminal #2 should get a white wire which is a neutral that comes off of the screw terminal of the relay. The only remaining wire is a black wire which goes to terminal #5 or the Normally Open. This is the standard connection however there are several options such as 2 speed pumps, pool cleaners, and variable speed pumps that take a different schematic. You can contact the manufacturer and they are very helpful getting you a wiring diagram via fax or email.