Cost of rewiring

[Tony Brooks]

Thanks Sam, I am just sorry this is far from an isolated case.

 

Here you are Erik - I can email it to anyone who wants it. Lots of questions now I suspect. Knowledgeable comments from other welcome.

 

 

I suspect the positive side of the bus bar is a later addition and there is another thick wire running form the domestic isolator to the domestic fuses/distribution board. If so this can stay in place and ignore the cable marked X

Edited August 31, 2018 by Tony Brooks

[WotEver]

2 hours ago, Tony Brooks said:

Thanks Sam, I am just sorry this is far from an isolated case.

 

Here you are Erik - I can email it to anyone who wants it. Lots of questions now I suspect. Knowledgeable comments from other welcome.

 

 

I suspect the positive side of the bus bar is a later addition and there is another thick wire running form the domestic isolator to the domestic fuses/distribution board. If so this can stay in place and ignore the cable marked X

Excellent diagram Tony. Better than the one I knocked up a couple of weeks ago for someone else. 

[Boater Sam]

Smashing diagram Tony, have you been saving your art skills for this post?

[Tony Brooks]

37 minutes ago, Boater Sam said:

Smashing diagram Tony, have you been saving your art skills for this post?

No lots of opportunity doing stuff for my course notes and the magazine. It is all done on a very ancient pre-windows GEM based vector drawing program that stopped being updated with W97. Now running under WINE on Linux. Regrettably I can't offer the vector file as its in a closed and now defunct format.

 

I think the diagram is probably poorly laid out, too many crossing lines.

Edited August 31, 2018 by Tony Brooks
Edited to remove idiot suggestion

[Mike Adams]

Just one question about your wiring diagram. If you close the LH master switch that would enable the engine to start but if the RH is left open is there not a potential for the alternator to have its output o/c which I understand is not a good idea.

[Tony Brooks]

7 hours ago, Mike Adams said:

Just one question about your wiring diagram. If you close the LH master switch that would enable the engine to start but if the RH is left open is there not a potential for the alternator to have its output o/c which I understand is not a good idea.

The thing that damages alternators is when their output is open-circuited when they are running and energised not simply started with the output open circuit. IN any case the VSR should connect the two banks as the voltage stars to rise so the alternator will still be charging the engine bank. In any case any domestic loads that are turned on will present a load to the alternator.

 

As with so much boat stuff its a compromise. Do you connect the alternator to the engine battery and take the risk that we know is real of burning out the relay contacts with full alternator output augmented by the higher starter battery output into a flat domestic battery or do you avoid that but leave the theoretical danger that you describe. Your scenario is probably no more likely that someone turning a master switch off with the engine running yet we rather tend to ignore that one and it does not seem to lead to many failures.

 

Now, IF the BSS was less blinkered they would accept that the diodes in the alternator, in effect, isolates the supply off when the engine is stationary and allow the main charging lead to be connected to the other side of the master switch than what you point out could not happen. I am fairly sure hundreds of boats are wired like this and the BSS inspectors do not check so pass them but I can not be seen to condone working against the BSS. I also suspect some owners modify the wiring at the master switch before and after their BSS examination.

[Mike Adams]

Unless I am missing something with the RHs switch o/c B+ on the alternator is not connected to anything other than any load on the bus bar. I not sure some electronics would like this as you have a 3 phase wave form of unknown voltage peeks. Interesting point on the BSS -it has never come up in any of my inspections. Yes but if the RHS is open and say an electrical load (lamps) are on and you swith off the lamps the alternator becomes o/c. Is it not better to have one switch on the negatives?

 

[Chewbacka]

59 minutes ago, Tony Brooks said:

The thing that damages alternators is when their output is open-circuited when they are running and energised not simply started with the output open circuit. IN any case the VSR should connect the two banks as the voltage stars to rise so the alternator will still be charging the engine bank. In any case any domestic loads that are turned on will present a load to the alternator.

 

As with so much boat stuff its a compromise. Do you connect the alternator to the engine battery and take the risk that we know is real of burning out the relay contacts with full alternator output augmented by the higher starter battery output into a flat domestic battery or do you avoid that but leave the theoretical danger that you describe. Your scenario is probably no more likely that someone turning a master switch off with the engine running yet we rather tend to ignore that one and it does not seem to lead to many failures.

 

Now, IF the BSS was less blinkered they would accept that the diodes in the alternator, in effect, isolates the supply off when the engine is stationary and allow the main charging lead to be connected to the other side of the master switch than what you point out could not happen. I am fairly sure hundreds of boats are wired like this and the BSS inspectors do not check so pass them but I can not be seen to condone working against the BSS. I also suspect some owners modify the wiring at the master switch before and after their BSS examination.

This is my understanding - Unlike lpg where the bss examiner is required to view the pipe for joints etc - including using a mirror or the customer removing panels etc - the requirement for cable switching is a visual check where it is visible, so if the examiner can see the cable is ‘on the wrong side of the switch’ then they should fail it, but if not visible the examiner should pass it.  Nor is there any requirement for the customer to answer any questions concerning wiring etc, so the examiner should not ask.  That is one reason the examiner may pass many boats.  Also the examiner may be aware that all normal vehicles are designed with the alternator permanently connected to the battery so may choose to not look too deeply.  I also suspect the risk of fire from a wonky switch is far greater than the risk of fire from a failing alternator, but then BSS does not always seem to consider the implications of their requirements, Gas fridges being a good example where more have died from CO poisoning from a generator running an electric fridge than ever died by CO poisoning from a fridge.  Maybe that is why they now want CO monitors...........

 

[Tony Brooks]

22 minutes ago, Mike Adams said:

Unless I am missing something with the RHs switch o/c B+ on the alternator is not connected to anything other than any load on the bus bar. I not sure some electronics would like this as you have a 3 phase wave form of unknown voltage peeks. Interesting point on the BSS -it has never come up in any of my inspections. Yes but if the RHS is open and say an electrical load (lamps) are on and you swith off the lamps the alternator becomes o/c. Is it not better to have one switch on the negatives?

 

First of all the diagram is for one specific boat that probably has another positive connection to the domestic fuse box and it's bus bars.

 

What did you not understand about the rising voltage would close the VSR & present the engine battery as the load.

 

What do you not understand about "the danger is disconnecting a running alternator from the load, not energising one when  open circuit. It takes time, maybe not much but still time for the voltage on the alternator to rise as it energises where as an open circuit is instantaneous. That time gives the regulator plenty of time to clamp the voltage thus preventing spikes. In fact that alternator may well contain a zener diode specifically to clamp any voltage spike to a safe level.

 

I agree the generating part of the alternator is three phase but once it has passed all three sets of diodes its DC with a ripple on top with, once the regulator has started working an RSM (if you can say that bout ripply DC) of about 14 to 14.2 volts in this case.

 

The thing that does the damage when a RUNNING alternator is open circuited is the almost immediate collapses of the stator magnetic field inducing one large voltage spike. There will not be a sudden collapse if its started open circuit.

 

I am not willing to waste any more time of this theoretical and pointless debate. The diagram is as far as I know the best compromise for the OP.

[bizzard]

Anyway, 99% of folk automatically, always, as a matter of course, or subconsiousely switch both isolator switches on BEFORE starting the engine. There's always going to be a 1% of goons that forget, don't, or think they know better.  I think TB's diagram is lovely, as good as the LT underground railway map any day, although mainly Central line.

Edited September 1, 2018 by bizzard

[WotEver]

4 hours ago, Mike Adams said:

Is it not better to have one switch on the negatives?

Absolutely not, and it’s one of the best ways I know of potentially starting a fire. 

[TheBiscuits]

1 minute ago, WotEver said:

Absolutely not, and it’s one of the best ways I know of potentially starting a fire. 

I prefer matches or a lighter...

[MtB]

I've never had a potential fire...

[WotEver]

1 minute ago, TheBiscuits said:

I prefer matches or a lighter...

They require the expenditure of energy...

Just now, Mike the Boilerman said:

I've never had a potential fire...

Never had a fuse blow, huh? Can’t happen without potential

[Mike Adams]

If it is an Incomplete diagram then I cannot comment further. In terms of battery isolation, it cannot make any difference if the battery isolator is in the negative lead. We always disconnect car batteries by removing the negative first which avoids any chance of the spanner contacting the body if disconnecting the positive first.

[Tony Brooks]

22 minutes ago, Mike Adams said:

If it is an Incomplete diagram then I cannot comment further. In terms of battery isolation, it cannot make any difference if the battery isolator is in the negative lead. We always disconnect car batteries by removing the negative first which avoids any chance of the spanner contacting the body if disconnecting the positive first.

Well, yes it can make a big difference. Cars are not boats and boats are allowed certain circuits to bypass the master switch. If you open circuit the negative then under certain circumstance damage can occur or even set fire to the boat. t is to do with current trying to get to negative via cables and maybe equipment  not designed for that purpose.

[WotEver]

34 minutes ago, Mike Adams said:

In terms of battery isolation, it cannot make any difference if the battery isolator is in the negative lead. 

Yes it can. A huge difference. The difference between starting a fire and not doing so. 

[Erik.narrowboat]

On 31/08/2018 at 15:31, Tony Brooks said:

Thanks Sam, I am just sorry this is far from an isolated case.

 

Here you are Erik - I can email it to anyone who wants it. Lots of questions now I suspect. Knowledgeable comments from other welcome.

 

 

I suspect the positive side of the bus bar is a later addition and there is another thick wire running form the domestic isolator to the domestic fuses/distribution board. If so this can stay in place and ignore the cable marked X

Thank you, this is great. I have been trying to identify each of the wires. I have no doubt your diagram is correct, but there are obviously a lot of other wires plus the wires that go to the ignition ate no hidden behind panels and are wrapped together so I can't trace them. I have added a photo (first photo) to show where things are. It's not a great photo but what you see it the electrics cupboard on the bottom left and the ignition on the to right. Just to give an idea of why I can't trace the wires to the ignition.

 

I was also wondering if the bus bar you are showing is the existing one or a new one?

I have taken a photo of the panel above that the wires on the bus bar connect to (photo 2).

 

I found another relay (photo 3) that connects the engine and domestics master switches and has two more wires that go to the bus bar and possibly the ignition. It is 120 amps. Could this be the one in your diagram going from the engine master switch with the text 'feed to ign switch - should be fused at 50 amps'?

 

The wire with a red X seems to be connected as you said.

 

There is also an alternator regulator they connects to the bus bar and possibly the ignition.

 

I hope this makes sense. I'm just trying to comprehend all the information before starting to change anything.

I am debating whether I should try to do it myself or pay someone to help with the right instructions. On the one hand I hesitate to try myself as there seem to be some dodgy connections, on the other hand with all the great support here I feel it would be more satisfying and also a good exercise to do it myself. Having knowledge of the systems on my boat will surely not hurt.

 

 

 

[bizzard]

Looks like a Harborough marine boat.

[WotEver]

17 minutes ago, Erik.narrowboat said:

I found another relay (photo 3) that connects the engine and domestics master switches and has two more wires that go to the bus bar and possibly the ignition. It is 120 amps. 

That sounds like it could be the split charge relay. Can you measure the voltage on the pins with engine running and not running?

 

And clean off all that nasty green corrosion. 

Edited September 2, 2018 by WotEver

[Erik.narrowboat]

Forgot to include the photo

I'm now away running some errands but will measure the voltage when I'm back

7 minutes ago, bizzard said:

Looks like a Harborough marine boat.

It is, how can you tell?

[bizzard]

1 minute ago, Erik.narrowboat said:

Forgot to include the photo

I'm now away running some errands but will measure the voltage when I'm back

It is, how can you tell?

That view through the back doors. The taffrail, gas bottle boxes ect. Lister SR2?

[Erik.narrowboat]

https://canalplan.org.uk/boat/66789

It's this boat

[bizzard]

4 minutes ago, Erik.narrowboat said:

https://canalplan.org.uk/boat/66789

It's this boat

Don't know where they got 36hp from, unless its  since beenfitted with a BMC engine. It would have normally have had either a Lister SR2-13hp or a SR3-18hp. Looks like its another Harborough marine boat behind you too.

[Erik.narrowboat]

It has a BMC 1.8. is/was Harborough marine a good boat builder