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use of galvanic isolators

I have recently acquired a 64 ft Narrow boat which spends time connected to shore power. I have been advised to fit a galvanic isolator to prevent corrosion. Is this necessary ?

Asked by: Robert Doody  | 2.00pm, Sunday 10 October

WW says:

In a word, yes. The galvanic isolator is fitted in the earth line and creates a break between your boat and anything around it that might have a slightly different electrical potential. This prevents your boat from possibly becoming an anode which is eaten away by surrounding metalwork to which it would otherwise be connected electrically. If you should have a fault on your boat, the isolator immediately reconnects the earth line so that any currents run safely to earth.
The 'Rolls Royce' solution to this problem is an isolation transformer but these are a great deal bigger and more expensive.
Unless you are absolutely certain what you are doing, you would be well advised to get it installed by a professional.

Graham Booth  | 5.07PM, Sunday 10 October

It is important for safety to have the onboard mains electrics earthed to the hull. To prevent possible damage to the boat hull through stray earth currents, a galvanic isolator is essential. If the mains power is not earthed to the hull the RCD safety trip will not work properly (the test button will however work giving a false sense of security).

Rupert Smedley  | 2.48PM, Monday 8 November

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