new member

[millsie]

Hello all ,
Just joined this site, often check the forums and think I could add some info
40+years marine electrician

[Karanga]

Hi there
Here is a question for ya then...!
I hope you get lots more, so that we can learn from a (ex) professional

I have a 30 year old aluminium cat.

That sort of vintage has obviously seen several iterations of electrical and electronic trickery. It currently has 12v and 240v (via inverter) wiring systems.

I have been clearing out old wiring, since not all has been removed when new stuff put in. For instance, when I installed a new masthead VHF aerial and coax, I removed 6.6kg of radio and TV coax from various nooks and crannies!!

But while digging into the deeper reaches of the electrical area, I found the negative busses for the 12v and 240v and earth bus for the 240v systems. But what surprised me was that these were bolted and connected to the aluminium hull.

Now, I thought everything was meant to be isolated from the hull...
All circuits do have their own positive and negative wires, so no circuits actually use the hull to complete their connection (as far as I have found).
All anodes appear to last well, with little erosion.
So, do I panic about electrons having access to the hull, or do I relax, accepting that some electrons are always going to leak to the hull and so the system might as well be grounded fully?

Tim

[Don C L]

Welcome aboard millsie! Your experience will surely be appreciated here!

[GordMay]

Greetings and welcome aboard the CF, millsie.

[millsie]

Hello Tim,
This is the way we still do Ally boats , actually Llyods approved.
Providing nothing uses the hull as a earth return it works well.
The method behind the madness ,
If a positive or worse, active 240VAC cable touches earth you will blow a fuse/cb
disconnecting the circuit and ensuring you don't lose the ally or your life.
Millsie.

[millsie]

PS Still working,love to be retired.
Millsie