Paul_KD7HB:
35 years is a seriously long time for a sewage system that relies on electricity. You should take time out and remove EVERY electrical connection and clean the wires and what ever they are connected to. Replace that which cannot be refurbished.
Paul
Oh for sure. The pump is only about 3-4 years old at this point. It was completed replaced. The floats were both shot. It has been semi-replaced for the time being, but I want to get something more permanent/robust in place (hence this project). Everything else is pretty simple. Filter is a simple thing to clean and is done monthly. Not much else to it really. The holding tank is pumped every two years or so.
I'm looking to run all new wiring through the existing conduits to the tank when I install the new float(s). One new wire was ran for this temporary solution, but it is only nmd90 and not nmwu. It will be replaced along with the current float once I get something else in the works.
I could buy the float I'm eyeing and simply run the pump on a piggyback plug for now. Then hook up the existing high water alarm as well. It's is only a local horn alarm so we'd have to be home to hear it. If I really wanted to keep this project cheap I'd simply find something that would run off a NO/NC simple circuit and notify me remotely if it gets tripped (high water). Keep everything else super simple for now. This might honestly happen sooner than later as I don't really trust the current float and we don't have a high water alarm either. Not a good thing.
HiQ:
....It's more of an issue that the internal float switch contacts just fail eventually. My biggest worry would be that the high level alarm float breaks first (unknown to me) and then the pump control float fails and we get a backup situation again....
This is exactly why it is best to use Normally Closed contacts if you can.
If you use Normally Open contacts you don't know if you have a fault, you are relying on the contacts closing when an alarm situation arises but if they are faulty you will not know and they will not close.
In contrast if you use Normally Closed contacts then you will get an alarm when the system fails. This may be a false alarm in the sense that the level may not actually be high it is just that somehow, be it wiring or poor contacts, your circuit has become broken.The important thing is that you know there is a fault.
Fire alarms, emergency stops, fail safe systems should all operate on Normally Closed contacts to minimise the possibility of undisclosed failures.
Did the switch contacts stop closing or no longer make an electrical connection when closing?
Did the contacts get stuck? Eg. The contacts are normaly closed and have locked in place or wires have corroded and are now shorted.
Without something to compair it to you can only make an educated guess.
This is why for redundency they use more than one or one set of sensors.
Here is the idea i have been rattling around in my head since reading this post.
Using a 75mm poly pipe (used for water or sewage) you put a cap on one end and drill holes to allow fluid but restrict solids from entering.
Then using a smaller pipe (say 20mm) that will fit into the first pipe, you mount your sensors to this using the pipe to run your cables and keep them dry.
Sensors to consist of two sets of three sensors, one reads LOW, the next for PUMP ON and the third for HIGH WATER ALARM.
Advantage of this setup is that the chance of all holes in the outer tube being blocked is slim, the whole assembly could fit between the two pipes you mentioned, with two sets of sensors (they are not that expensive compaired to pumping out the basement) is that you monitor both and if one set reads different you set off an alarm.
If you run normaly open and one sensor closes but the other does not you go with the one that closed but activate an alarm to warn of sensor fail.
Using this you can just wire the HIGH WATER direct to an alarm.
This way you can put the sensor tube into a high container for testing before fitting to the septic.
Begin programming the Arduino for the new sensors then add a current sensor to the motor with a relay to turn the motor on and off.
This way when the motor is activated if no current is drawn then motor not working!