Jabsco electric blows fuse

[rossny]

Hi, my head works fine most of the time but the occasional fuse blowing is becoming more frequent lately. Changing the fuse does not always fix it immediately but it will work later. Any ideas?

[Pete7]

Are the wires and connections clean and of an appropriate size for the wire run?

Pete

[tkeithlu]

Peggy Hall, the forum's Princess of Poop, should step forward soon. Free advice from her should be treasured.

OK, an increase in total resistance in the electrical circuit. Start with the non-messy job: Inspect and polish (fine sandpaper) every connection in the ciruit. Look for deteriorated wire and replace it. If that doesn't do the job, it gets messy. There are lots of opportunities for hair, string, and other stuff to wrap itself around the motor shaft (a single shaft does all the pumping). Disassemble, carefully note (photograph) what goes on in what order, clean it all, and see that the motor turns freely. Reassemble.

Oh, and be glad that you don't have to do it very often.

[peghall]

That the toilet works fine most of the time but only occasionally blows the fuse may provide a good example of the reason why electric toilets need to be on their own dedicated circuit with its own breaker, shared by nothing else--not even cabin lights--that can either pull power away from the toilet or overload the circuit. Just turning on something else that's on the same circuit may not blow the fuse...until you flush the toilet. If your toilet IS on its own dedicated circuit, follow the advice that tkeithlu and Pete have offered.

An afterthought: Is it possible that the fuse is too small? If your toilet uses sea water, it draws 16 amps and the fuse should be 25. But don't even think of increasing the fuse size unless the toilet is on its own dedicated circuit!

Which model is the toilet? I can send you a link to the owners manual for it that includes electrical specs if you don't have one.


Btw...thanks for the compliment!



--Peggie

[stormalong]

Originally Posted by tkeithlu

OK, an increase in total resistance in the electrical circuit. Start with the non-messy job: Inspect and polish (fine sandpaper) every connection in the ciruit. Look for deteriorated wire and replace it. If that doesn't do the job, it gets messy. There are lots of opportunities for hair, string, and other stuff to wrap itself around the motor shaft (a single shaft does all the pumping). Disassemble, carefully note (photograph) what goes on in what order, clean it all, and see that the motor turns freely. Reassemble.

Actually an increase in current is due to a DECREASE in resistance.

I agree that the motor should be inspected. A stalled motor draws a lot of current. It could me the motor failing or something loading up the motor more than expected. Disassembly and inspection is the first step. Better sooner than later as these things only get worse.

[Boatyarddog]

Originally Posted by stormalong

Actually an increase in current is due to a DECREASE in resistance.

I agree that the motor should be inspected. A stalled motor draws a lot of current. It could me the motor failing or something loading up the motor more than expected. Disassembly and inspection is the first step. Better sooner than later as these things only get worse.

Stormalong: informed!
Thanks.

What happens to the current in a circuit if the resistance is increased?
Voltage is analogous to pressure like water pressure out of the tap on the sink. The current is analogous to the amount of water flowing out of the tap. Resistance is analogous to the amount of restriction the tap places on the water flow.

If the pressure increases (voltage), more water flows (current). If the restriction increases (resistance), less water flows. It's a similar thing with electricity.

Have you ever heard of Ohm's Law? It is a mathematical equation that represents the relationship of voltage, current and resistance.

I = V/R

The current (water flow) = the voltage (pressure) / restriction (resistance).

So, to answer your question, from the above analogy and mathematical equation, you can see that if the resistance is increased and the voltage stays the same, the current will decrease.

I hope this helps your understanding.
SV Cloud Duster

[Bycrick]

I once had a similar problem with a bilge blower. It would run for "a while", then blow the fuse. It was drawing the recommended current. After going through a bunch of burned out fuses, one of the wires broke and slid out of the fuse holder body. The wire had obviously made a poor connection to the fuse body, inside the holder, and was getting warm enough that the fuse would blow at well below the rated current. It took me months and a lot of fuses to find the problem.