Transformer primary vs secondary

[JohnW123]

Hi,

new here and english is not my native language, so hope you understand the question.

I live in a house with a well outside in which water from the bathrooms is collected in before it is pumped out to the public sewer system.

In this well I have one of these, which works like a on/off switch:

Inside the house i've got a small 12V circuit with a speaker on (alarm) which turns on if the the above thing registers too much water in the well.
The circuit consists of a transformer which converts 230V AC to 12V DC and starts the alarm as long as it is powered.

Currently the circuit is like this:
230V -> the on/off switch in the well -> circuit

A specialist on the well pump, told me to change the circuit to be like this:
230V -> circuit -> the on/off switch in the well
Reason being: 230V into a water well is not a good idea

So his suggestion is to move the on/off switch in the well to the secondary 12V side of the transformer rather than the 230V primary side.

Will this not create a problem as the primary side will be energized permanently, but disconnected on the secondary side most of the time?
Will the transformer overheat/get damaged?
Or is it ok?

Thank you in advance

 

[Nigel Goodwin]

So his suggestion is to move the on/off switch in the well to the secondary 12V side of the transformer rather than the 230V primary side.

Will this not create a problem as the primary side will be energized permanently, but disconnected on the secondary side most of the time?
Will the transformer overheat/get damaged?
Or is it ok?

It's not a problem, and is a perfectly normal thing to do.

However, float switches on pumps are normally mains powered, as are the submerged pumps.

 

[alec_t]

A good quality transformer draws little primary current when the secondary is unloaded or only lightly loaded (such as when the speaker circuit is unpowered).

 

[JohnW123]

Thank you both for the answer.

The guy told me im running a old style pump. New style pumps does not have 230V in the float switches, but 12V.

If/When the float switches starts leaking, the 12V switches will not turn off the residual current circuit breaker, but the 230V will

 

[Nigel Goodwin]

The guy told me im running a old style pump. New style pumps does not have 230V in the float switches, but 12V.

We've supplied brand new pumps, just in the last few weeks to a major Water Utilities company, the float switches (as well as the pump) run at 230V, and the switches WON'T leak - I dismantled one of the original float switches (because I'm nosey!), which was a VERY hard job, and there's no way they are going to leak water.

 

[JohnW123]

Here they do. I got all 3 replaced (start/stop/alarm) 11 years ago, and yesterday the alarm one cause it leaked. The guy told me life expectancy per float switch is 10 years, and they replace them regularly, especially the ones used for dirty water - like my well

 

[ronsimpson]

My float switch is 18 years old. It switches main power. I can see that maybe the wire insulation will get old and crack with time. I think the plastic cracking is a function of sun light which there is none.

Where I live the well can run form 110 or 220. The pumps have a wiring change so they can work from either power. I find 220 better because the current is 1/2 and thus the loss in the wire is 1/2.

At one time I had a power line switch for the pump and a 5 volt switch for the computer. But too many wires in the well. Now I have the power line switch and the computer looks the pressure. When the water level is too low the pump is shut off, then when the pressure drops low the computer see that.

 

[Nigel Goodwin]

Here they do. I got all 3 replaced (start/stop/alarm) 11 years ago, and yesterday the alarm one cause it leaked. The guy told me life expectancy per float switch is 10 years, and they replace them regularly, especially the ones used for dirty water - like my well

The one you posted the picture of looks pretty crappy to be fair, the ones I've seen are MUCH sturdier than that.

 

[ronsimpson]

 

[Diver300]

If you are only running a buzzer, you don’t need a big transformer. A modern 12V power supply will use less than 0.5 W.
Very few transformers or power supplies will overheat if they are permanently powered. You can just feel how hot your transformer gets. If it gets more than warm after an hour it may overheat if left on permanently. Also, if it is getting hot, the electricity cost may mean it is worth buying a better power supply.

I would not go and change a working system just because more modern ones are made differently. I would leave it with 240 V connected to the switch. The switch will fail if it fills with water, and the voltage won’t make that any more or less likely.

If the buzzer is never working for a long time, you could just us a battery for the 12V. Smoke alarms often work on batteries only.

 

[ronsimpson]

If you are only running a buzzer, you don’t need a big transformer.

Use part from a door bell. 24V transformer and buzzer.

 

[Nigel Goodwin]

This is something like the one I took to pieces, it required a lot of hacksaw work - I kept the big ball bearing because it was pretty cool!

 

[Dr_Doggy]

I use a GFCI to protect my pumps.. similar to post 9, it makes me feel better when im splashing around in the water too

 

[dr pepper]

Last time I replaced a float switch in the rainwater sump i too pulled the old one apart, it had a V3 microswitch inside.
the normal cause of failure is the wire goes open due to all the movement.

 

[hyedenny]

new here and english is not my native language, so hope you understand the question.

Your English is way better than many here whose native language is English!