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robtheplod

Replace Water Pump - rejig...

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31 minutes ago, BWM said:

I was under the impression that modern cable is more efficient and can pass more current for their size?

Baloney.  There is no substitute for solid copper unless its silver or gold!

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55 minutes ago, BWM said:

I was under the impression that modern cable is more efficient and can pass more current for their size?

 

I think that may be down to the thickness of insulation rather than the copper itself.

 

Compare standard PVC cable with the thinwall alternative.

 

https://www.autoelectricsupplies.co.uk/category/10

  • Greenie 1

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The current rating of a cable is down to two criteria :

 

1) The amount of copper (cross sectional area). The bigger it is the higher current it will carry.

2) The temperature rating you are prepared to accept.

 

The thickness of insulation determines the voltage rating. The thicker it is the higher the voltage rating.

 

 

There is a bit more to it (bundles, in conduit, in air etc etc) but that is the essence of it.

 

I spent 9 years as a cable designer and Product Manager for (what is now) Draka cables, and have several patents in my name.

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10 minutes ago, Alan de Enfield said:

I spent 9 years as a cable designer and Product Manager for (what is now) Draka cables, and have several patents in my name.

Unfortunately, it seems we've had enough of science and experts...

 

:banghead:

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1 hour ago, Boater Sam said:

Baloney.  There is no substitute for solid copper unless its silver or gold!

That's a bit simplistic, a look at the wiring looms of today's vehicles shows a big reduction in the size and stiffness of most cabling. 

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49 minutes ago, Sea Dog said:

Unfortunately, it seems we've had enough of science and experts...

 

:banghead:

Science is fine so long as its not rammed down yer throat by school kids ?

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21 minutes ago, BWM said:

That's a bit simplistic, a look at the wiring looms of today's vehicles shows a big reduction in the size and stiffness of most cabling. 

That’s down to two reasons. 
 

  • Modern cable is ‘thin wall’, meaning that the insulation is both thinner and more flexible. 
     
  • Modern cars rely on a lot more relays to switch high currents devices, so the cables often carry little more than a signal current. 
     

Nobody has invented less resistant copper - it’s the same copper as we’ve used for a hundred years or more. 

2 hours ago, BWM said:

I was under the impression that modern cable is more efficient and can pass more current for their size?

That simply isn’t true. In fact, modern regulations have increased the size of cables for any given current rating compared to say 50 years ago. 

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37 minutes ago, WotEver said:

That’s down to two reasons. 
 

  • Modern cable is ‘thin wall’, meaning that the insulation is both thinner and more flexible. 
     
  • Modern cars rely on a lot more relays to switch high currents devices, so the cables often carry little more than a signal current. 
     

Nobody has invented less resistant copper - it’s the same copper as we’ve used for a hundred years or more. 

That simply isn’t true. In fact, modern regulations have increased the size of cables for any given current rating compared to say 50 years ago. 

I have probably simplified the physical size of the wire against the size of the core, not being an electrician. Has been interesting to find out that this is mainly down to the insulation. I'm sure that last time i bought some the retailer said that the core was more efficient, having more strands but i may have misunderstood. 

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20 minutes ago, BWM said:

I have probably simplified the physical size of the wire against the size of the core, not being an electrician. Has been interesting to find out that this is mainly down to the insulation. I'm sure that last time i bought some the retailer said that the core was more efficient, having more strands but i may have misunderstood. 

More strands makes cable more flexible. That’s why many of us use welding cable when we need big fat cables. 70mm2 welding cable with 624 strands, or Oceanflex with 912 strands, or even some of the newer very flexible battery cable with 1330 strands is much more bendy than a cable with say only 200 strands. 

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6 hours ago, BWM said:

I was under the impression that modern cable is more efficient and can pass more current for their size?

Its not the current carrying capacity that is normally the problem on boats, its usually down to volt drop.  Very few cables on boats have their size limited by the current carrying capacity

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1 minute ago, ditchcrawler said:

Its not the current carrying capacity that is normally the problem on boats, its usually down to volt drop.  Very few cables on boats have their size limited by the current carrying capacity

Tis unfortunate that few builders of long boats realise that.

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9 minutes ago, Alan de Enfield said:

Tis unfortunate that few builders of long boats realise that.

When you look at some of the basic things that come up on here, Fridge and water pump wiring too small and plumbing pumps in solid pipe, no expansion of calorifiers etc

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I've now changed the pump and added hoses. I just connected the flexible hose to the existing connections with convertors in the end and it seems to be a good fit (surprisingly!). The pump runs much quieter (and the taps no longer vibrate!) but is still nice and audible (background hum now..). I like the idea of seeing the water come in/out of the pump and as the pump is more accessible I'm more likely to winterise properly (remove hoses and drain etc). Thanks to everyone who helped me on here!

20191214_103633.jpg

  • Greenie 1

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19 minutes ago, robtheplod said:

I've now changed the pump and added hoses. I just connected the flexible hose to the existing connections with convertors in the end and it seems to be a good fit (surprisingly!). The pump runs much quieter (and the taps no longer vibrate!) but is still nice and audible (background hum now..). I like the idea of seeing the water come in/out of the pump and as the pump is more accessible I'm more likely to winterise properly (remove hoses and drain etc). Thanks to everyone who helped me on here!

20191214_103633.jpg

The foil tray is an excellent idea. Very cheap, keeps the floor and bilge dry and lets you spot leaks quickly from a pump that is on its way out. Seen recommendations to use a tray before, but a foil one is an excellent size and shape, provided you eat the lasagna first! (Yes I know you can buy just the trays)

 

Jen

  • Haha 1

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The problem I had before was it was pretty impossible see what was leaking. Moving the pump away from the pipes gives me more of a chance plus the tray will help. My only concern is if the pump leaks and fills the tray this wont help the pump electrics, so I've put in a cheaper leak detector. The pump will only be live when we're on the boat so hopefully this will work ok!

 

As it turns out the leak was from the filter, so I now have the added benefit of a spare pump!

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1 hour ago, robtheplod said:

I've now changed the pump and added hoses. I just connected the flexible hose to the existing connections with convertors in the end and it seems to be a good fit (surprisingly!). The pump runs much quieter (and the taps no longer vibrate!) but is still nice and audible (background hum now..). I like the idea of seeing the water come in/out of the pump and as the pump is more accessible I'm more likely to winterise properly (remove hoses and drain etc). Thanks to everyone who helped me on here!

20191214_103633.jpg

I used a plastic tray that they sell meat in and also  added one of these "9V Water Leak Alarm Flood Level Overflow Detector Sensor Pool Home Security UK"

image.png

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On 09/12/2019 at 11:46, robtheplod said:

Thanks so much for the replies. Will defiantely implement the flexible hoses and move bits about. I'm tempted to put the pump within a large foil turkey tray to keep an eye out for leaks. I have one of these cheap Chinese water detectors which I could mount in it...… good idea, bad idea or silly idea???!!

I mount mine in a foil tray, heal and easy way.

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On 11/12/2019 at 07:36, Boater Sam said:

Baloney.  There is no substitute for solid copper unless its silver or gold!

multi-strand for proper boaters

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