Wiring a Relay - Help Please

[John V]

Twice I had microswitches die in Parmax pumps. Miniature and subminiature microswitches are not really man enough for the inductive DC switching they are used for although from a suppliers point of view they are more than adequate as even under very frequent use conditions they will well exceed the warranty period and from a manufacturers view they are ideal as they are cheap, manufactured all round the world by multiple companies and easily sourced.

From my point of view they are a weak link and it avoids a probable failure by adding a relay.

(incidentally I have a 24V system and have never {touches wood} had a pump motor fail so I wonder if low motor volts on 12V systems and subsequent overheating contributed to the the motor failures another poster refers to)

[Tony Brooks]

snip

 

(incidentally I have a 24V system and have never {touches wood} had a pump motor fail so I wonder if low motor volts on 12V systems and subsequent overheating contributed to the the motor failures another poster refers to)

 

I am sure it is but not because of being 12V, I suspect many suffer voltdrop on undersized wiring.

[John V]

 

I am sure it is but not because of being 12V, I suspect many suffer voltdrop on undersized wiring.

 

agree, but I was implying that, as it is rarely a problem on 24V systems due to the smaller current draw (and cables that are normally large enough even when installed by the most penny pinching)

[Paul C]

 

agree, but I was implying that, as it is rarely a problem on 24V systems due to the smaller current draw (and cables that are normally large enough even when installed by the most penny pinching)

 

I wish more people would see the sense in choosing 24V when building a narrowboat. By its very nature (being long...) an effort to simultaneously keep the thickness of the (bundle of) wiring and voltdrop down should be made, and if specifying new components there really isn't much or any price difference. I guess the only thing is a decent stereo, and for that (and maybe other items - don't know?) a 24V-12V converter could be installed.

[nicknorman]

I wish more people would see the sense in choosing 24V when building a narrowboat. By its very nature (being long...) an effort to simultaneously keep the thickness of the (bundle of) wiring and voltdrop down should be made, and if specifying new components there really isn't much or any price difference. I guess the only thing is a decent stereo, and for that (and maybe other items - don't know?) a 24V-12V converter could be installed.

That's one way of doing it, another is to use a decentralised distribution system like we have. We've got a 16mm^2 12v "ring main" ie effectively 32mm^2 to the front of the boat, and from the node there it is less than 2 metres of "normal" wire to the water pump.

[Paul C]

That's one way of doing it, another is to use a decentralised distribution system like we have. We've got a 16mm^2 12v "ring main" ie effectively 32mm^2 to the front of the boat, and from the node there it is less than 2 metres of "normal" wire to the water pump.

 

Remind me of the cost difference between yours and a normal 12V system?

[Tony Brooks]

 

Remind me of the cost difference between yours and a normal 12V system?

 

As long as it is not a bus (as in Canbus, Empirebus) system ten I suspect the extra cost would not be that great. What I have against it is that unless the documentation is absolutely top notch so those trying to diagnose the system know exactly where the fuses are located. I think such systems have a fair bit to commend them but I would rather use three or four local distribution points so the location of the fuse/mcbs and connections are more obvious.

[nicknorman]

Remind me of the cost difference between yours and a normal 12V system?

No idea since there are some saving in terms of switch/fuse panels as well as the considerable extra cost of the kit, but I don't think the discussion was about the cheapest way - if so just installing a thicker cable for the water pump is probably the most cost effective. Going 24v brings its own inconveniences, as well as advantages, and I was just pointing out that 24v is not the only solution to the long distance wiring issue.

Edited July 5, 2015 by nicknorman