Another electrical question.

[glynnffc]

When I have to run a wire from the negative bus bar to the anode, how do I work out the size of cable? This cable carries the whole boat load of stuff , but surely can't be sized according to the usual formula.

Sorry for two in a row , but I am puzzled!!!!!!

 

[Cloven]

I may be wrong but the usual arrangement is to run a wire from the anode to the engine block as in most circuits, the engine block is connected to the battery negative and so to the rest of the circuit.

 

[pappaecho]

as the current and voltage are minute, the wire can be small in x sectional area

 

[ShaunG]

Hi Glynn,

If you are connecting the DC Negative to the Anode to tie the ground systems together then it is usually recdomended that 4mm2 is used, however from your post it would seem that you are linking the whole negative system to the anode from the bus bar, in this case the potential current would be the total of all your current drawn if the anode is to be used as ground. As said above the engine/battery should be connected as negative and then the engine/battery - connected to the anode

 

[nimbusgb]

[ QUOTE ]
I may be wrong but the usual arrangement is to run a wire from the anode to the engine block as in most circuits, the engine block is connected to the battery negative and so to the rest of the circuit.

[/ QUOTE ]

The engine block is not always connected to the battery negative. In some systems the engine operates isolated from the rest of the systems ( my benne does it this way ).

 

[VicS]

The the important fact is that the anode should be connected to the item(s) it is to protect with a good low resistance connection. The wiring should not be carrying any other current so on that score the negative bus bar may not be the most appropriate. Commonly to the engine block if that is the way in which you are attempting to protect the stern gear

MG Duff recommend 4mm². Quite heavy and not small at all as suggested earlier!

see http://www.mgduff.co.uk/pdfs/Fitting_Instructions.pdf

 

[William_H]

It is not clear from your post if current (other than electrolysis current) will actually flow through the wire connected to negative bus bar. If the bus is used simply as a convenient negative connection and nothing else is connected to the wire then no other current as it should be.
In this case the size of the wire is purely dictated by robustness needed for a wire in the bilges which may not be checked often and which if damaged (physical or corrosive) could cause problems that do not immediately show up. So go for a wire size that is tough enough to last. olewill