Electrical

[jeb]

Whilst tinkering with my alde boiler today I managed to accidentaly dislodge the negative cable, I was a bit puzzled at first if indeed it was the negative connection to the Alde because the boiler was still running. It soon became apparent that it was indeed the negative to the Alde so I turned the power off,out of curiosity I turned the power back on and the boiler fired up without the negative connected. Is this normal ?

[Gibbo]

Whilst tinkering with my alde boiler today I managed to accidentaly dislodge the negative cable, I was a bit puzzled at first if indeed it was the negative connection to the Alde because the boiler was still running. It soon became apparent that it was indeed the negative to the Alde so I turned the power off,out of curiosity I turned the power back on and the boiler fired up without the negative connected. Is this normal ?

 

Yes.

 

It's probably picking up a negative from the hull via another route. Like a gas pipe (!!!!) or water pipe. Or possibly the casing touching the hull.

 

I don't like conductive gas and water pipes for this very reason. I like to put a small insulated section in them.

 

Gibbo

[Keeping Up]

I don't like conductive gas and water pipes for this very reason. I like to put a small insulated section in them.

Is that permitted for gas pipes?

[Gibbo]

Is that permitted for gas pipes?

 

I've no idea I haven't done installations for a long time. But I don't see why not. The pipes to the gas bottles are rubber. There are rubber gas pipes inside many gas burners. Things may have changed. I dunno.

 

Gibbo

[jeb]

Yes.

 

It's probably picking up a negative from the hull via another route. Like a gas pipe (!!!!) or water pipe. Or possibly the casing touching the hull.

 

I don't like conductive gas and water pipes for this very reason. I like to put a small insulated section in them.

 

Gibbo

 

Thanks Gibbo

I was thinking gas pipe and is now certain, but how to insulate the pipe where it exits the gas locker and passes through the front bulkhead. Hmm

[dor]

I shouldn't worry about the gas pipe. The current is only very small. it is probably earthing through the flue as well. But reconnect the direct negative.

Edited November 20, 2008 by dor

[jeb]

I shouldn't worry about the gas pipe. The current is only very small. it is probably earthing through the flue as well. But reconnect the direct negative.

 

Would there be enough current to power my tunnel light and horn ?

 

NO NO NO only joking

 

Thanks Dor

[simonk]

Whilst tinkering with my alde boiler today I managed to accidentaly dislodge the negative cable, I was a bit puzzled at first if indeed it was the negative connection to the Alde because the boiler was still running. It soon became apparent that it was indeed the negative to the Alde so I turned the power off,out of curiosity I turned the power back on and the boiler fired up without the negative connected. Is this normal ?

 

I found this with my Alde installation too. Strange readings were happening as the DC system was not earthed to the hull (no discussion required on that...). It is now but I thought it a good idea to stop these spurious hull connections in any case - since my boat is 24V and the Alde needs 12V I used an isolated DC-DC converter so that sorted it out. If you look inside the Alde there is a connection from the -ve input to the metal work - I tried removing this but the ignition spark seemed to click constantly.

 

(The other place I found a spurious hull earth was between a negative pin and the shell in one of those 3-pin 'oudoor' plugs for the front light and horn, via a retaining screw).

[chris w]

(The other place I found a spurious hull earth was between a negative pin and the shell in one of those 3-pin 'oudoor' plugs for the front light and horn, via a retaining screw).

Another favourite hull connection is if you have a radio aerial fitted through the roof and you didn't cut the braid in the aerial lead and fit an RF bypass capacitor across the cut.

 

Chris