Background
I'll try and keep this short and sweet. I have a dehumidifier in my basement that is currently connected to a condensate pump. Basically the dehumidifier is pulling moisture out of the air and depositing it into this pump which automatically turns on when the water level reaches a certain height and pumps the water out and into the drain.
These types of pumps are typically used alongside house air conditioners which also draw a lot of moisture out of the air due to the dehumidifying nature of air conditioning. As a result, the pump also has a safety overflow switch which is basically two low voltage wires sticking out the back of the pump that are intended to be wired in series with the low voltage thermostat circuit sticking out of an air conditioner so that in the event that the pump fails and backs up, the switch will trigger and turn the air conditioner off so that the pump doesn't continually overflow for hours and hours on end.
My situation though is that dehumidifiers typically do not have any sort of hookup for these low voltage safety switch wires.
The Idea
I'm interested in designing some sort of microcontroller that will interface with this low voltage safety switch and detect when it gets triggered so that I can do something to notify myself that something has gone wrong. I'm still forming what that "do something" looks like, but I think at this stage of the project it isn't a big deal. It could be as simple as sending an email to something more complicated like getting a message to a smart outlet to turn off power to the dehumidifier.
The Problem
The issue I'm having is that although I have one foot in the microcontroller world in my professional life (maybe half of a foot), I actually rarely do work on these devices other than running software on the boards without interfacing with anything outside of them aside from an odd GPIO input here and there.
As a result, I'm looking for people to point me in the right direction for how to interface between an Arduino board and this low voltage wire. I see some Arduino projects related to home HVAC systems use relays to open and close switches to drive systems to turn on and off but my scenario is a little different in that I just want this device sitting there polling an input waiting for the pump to issue the command.
Is a relay what I should be looking for or am I way off base?
edit: I think it's worth mentioning that the wires coming out of the pump are labeled COM and NO with a third switch - NC - available. Here is the quote from the manual for the pump:
Safety switch: The safety overflow switch should be connected
to a class II low voltage circuit. To control a thermostatic circuit
the COM and NO connections from the safety switch are to be
wired in series with the low voltage thermostat circuit to shut
down the heating/AC circuit. The COM and NC switch contacts
may be used to actuate a low voltage alarm circuit (connected
in series) if the heating/cooling system can not be disrupted.
The safety switch comes from the factory with leads connected
to the COM and NO switch terminals. Typical hook-up of “NC”
circuits would be (Figures 2 & 3).