Full electrical configuration

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rick.jones
rick.jones's picture
I'd also like to add a tip

I'd also like to add a tip regarding feeding cable through difficult runs (e.g. in the ceiling or through the bilge space). Once you've fed something through to find the route, pull a piece of strong synthetic cord (so it won't rot) through. Then use that to pull your cable(s) through, and at the same time include another length of cord. Leave this cord in place, with the ends tied off so they don't get lost. Then when you want to thread another cable (almost inevitably!) you've got the cord there ready to use.

And of course if you do use that cord, pull another one through to replace it!

Rick Jones (Treasurer) 1994 Mac 19 "White Lightning", Isle of Wight

david.claassen
david.claassen's picture
Great idea, Rick! I should

Great idea, Rick! I should get started on this plan later in the week, and will keep asking questions until I get it done. Has anybody placed their rotary selector switch directly under the last step of the companionway ladder? That seems to be the easiest solution cable-wise...my theory being that it is a pain to get at regardless...

David Claassen

"Logan's Run"

2006 26M

roly.simpson
That's exactly where mine is

That's exactly where mine is Dave and I think also noted same on John Pompeii boat . It's easy to run thick cables to it from batteries but a bit awkward to reach to attach wiring. Ideally best to feed a single cable off the outflow terminal to go to a positive bus bar /fuse board / connection post.

Happy scrabbling!

Roly

john.pompei
john.pompei's picture
Hi David,

Hi David,

Yes, Roly is correct my 3 position switch is under the steps and it seems OK there.

During the lockdown I moved the bilge pump switch next to the 3 way one, before it was next to the other isolator behind the galley and was easy to knock on unintentionally.

Regards,

John

roly.simpson
Can anyone tell me how to be

Can anyone tell me how to be sure that my coolbox does not bridge the AC/DC separation as noted by Rick. It is a proper Dometic cooler bought from yacht chandler and the manual says that it automatically cuts out DC once AC switched on. Hence I have both plugged in so that AC will take over once shore power connected. Manual makes no mention of the specific issue.

Roly

rick.jones
rick.jones's picture
Hi Roly

Hi Roly

Do you have a test meter that will measure resistance or continuity? (I.e. the ohms setting)

You need to unplug the coolbox, then measure between the earth pin on the mains plug, and the outer connection on the 12v plug. There should be no continuity (infinite ohms). That's to say no difference in reading between touching the pins and not.

If you get any measurable resistance then the circuits are not isolated.

Rick Jones (Treasurer) 1994 Mac 19 "White Lightning", Isle of Wight

roly.simpson
Hi Rick. I do have a meter

Hi Rick. I do have a meter but Im not quite clear. It seems that the plugs will definately be isolated since one comes direct from shore power and one from the battery. Did you mean the sockets in the cool box? Otherwise the only way I could see a connection would be through my charger that is also lugged into the 3 socket camping style cicuit breaker box.

Roly

rick.jones
rick.jones's picture
Hi Roly

Hi Roly

Yes, I mean test the coolbox itself, when it's not plugged in. You're trying to determine if the circuitry in the box bridges the 12V and mains earth. I think it's highly unlikely that it would.

I would expect the charger to be fully isolated.

Rick Jones (Treasurer) 1994 Mac 19 "White Lightning", Isle of Wight

david.claassen
david.claassen's picture
I've started moving things.

I've started moving things. When removing the old shore power lead, I was a bit surprised to see the negative earthed to one of the 12v breaker panels. Is this normal?

David Claassen

"Logan's Run"

2006 26M

rick.jones
rick.jones's picture
Hi David

Hi David

Not sure what you mean by "negative" relating to the shore power lead. Mains has live (brown), neutral (blue), and earth (green/yellow). L & N should never be connected to anything other than 240V equipment. On, for example, a steel hull vessel, earth would be connected to the hull for safety. But this can set up an electrolytic circuit through the water, resulting in corrosion of the boat (which can be severe and fast).

With a GRP hull, there is nothing particular to earth, so there's nothing to be gained by connecting to the 12V circuit. But maybe that's what someone has done? It will create a corrosion problem with the outboard, so best to keep mains and 12V completely separate. If they are kept connected then you should plug shore power via a galvanic isolator.

Rick Jones (Treasurer) 1994 Mac 19 "White Lightning", Isle of Wight

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