electrical question: pump for fountain
I have a new fountain in a remote location. I have a conduit running to that location, but it is already in use for 24-volt valve-control circuits, and the pump for the fountain runs on 110 volts. And, as far as I know, you’re not supposed to mix 24-volt and 110-volt circuits in the same conduit.
So I say to myself: I’ll just provide 24-volt power at the house-end of the conduit, and step it back up to 110 volts at the fountain-end of the conduit. Should be easy, as the pump only requires 20 watts of power (less than 1 amp at 24 volts).
So I tried a mock-up on my workbench: 110 volts into a 24-volt transformer like you would use to power furnace relays, the output of that transformer into the 24-volt leads of a second transformer of the same kind. Of course, I expected to get 110 volts out of the second transformer, but instead got zero, even with nothing connected to the output of this arrangement!
As far as I can tell, both transformers have no diodes or other oddities built into them: they seem to be just transformers.
Any clues as to why this doesn’t work as I expected it to?
Bob Chapman
Replies
the circuit is too long ?
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Are you sure the transformers are OK? You should get something out even if you can't support the expected load.
If you really want to be safe you still need GFCI protection out there.
Have you just thought about a 24v pump.
Edited 5/30/2009 9:57 am ET by gfretwell
I think the second xfr is just sucking down what 's left of 24, he didn't say how long the run was.
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He said this was a work bench test
he sure did, lets hope then that "same kind" means identical.
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If I'm reading this correct, would it be easier to run 120 vac to the pump location and then step down to 24 AC?
Change the 24v to a 120v circuit and install the 24v xformer in a weatherproof enclosure at point of use.
You screwed something up, or have defective transformer. A plain, vanilla transformer doesn't care (much) which side is the primary and which is the secondary. (Efficiency is slightly improved if the inner winding is the primary.)
You might measure the primary and secondary resistances to be sure that your transformers are good.
I agree with England1.
It wold be better to swap out the run in the conduit to 110, and then put the transformer out there.
The other option is to get a low voltage pump.
But, if you are running any distance, the higher voltage to the pump is a far better idea.
I would get a 24V pump. They have ones that are connected to a solar PV collector.
When the sun shines, they pump. Simple.
Simple good, complicated bad. Me like simple.
Will Rogers
Edited 5/30/2009 11:50 pm by popawheelie
Problem resolved! Bad transformer. Now it works fine on the test bench.
Thaks for all your suggestions.
Bob CHapman
Figured it had to be. It's a textbook setup, and not much (other than a bad xformer) can screw it up.
As I stood before the gates I realized that I never want to be as certain about anything as were the people who built this place. --Rabbi Sheila Peltz, on her visit to Auschwitz