AC grounding plate

Things 12V and 24V
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terryk
Posts: 320
Joined: Wed Jan 10, 2007 10:37 pm
Location: Gosford

AC grounding plate

Post by terryk » Tue Jun 10, 2014 9:38 pm

Hi builders, a 240v question. I guess all the cats capable of having 240v shore power on board have an AC grounding plate attached to your hull below the water line?? I read somewhere that this is now law.
Cheers
terryk

DA
Posts: 16
Joined: Wed Sep 08, 2010 4:56 pm
Location: sunshine coast

Re: AC grounding plate

Post by DA » Sun Jun 29, 2014 10:13 pm

I dont have grounding plate but went with Sure Power Solutions 3 Way Reverse Polarity Module (3WMCRL)

Sure Power Solutions 3 Way Reverse Polarity Module
With current 240Volt AC electrical safety rules and regulations for boats becoming increasing stricter, Keoghs Marine Electrics is proud to offer a real solution which improves electrical safety on vessels. The Surepower PEC Module is a Electronic monitoring self diagnostic module with LED indication senses the incoming 240 Volt AC Shore Power polarities and earth continuity. The three LED indicators advise if (1) Shore Power is Correct(2) Supply Polarity Faulty(3) Supply Earth FaultIf the polarity is correct and the earth is present then the module will switch 240volts to energise a contactor allowing power to go to the switchboard giving you sure power.The LED display can also be also repeated in a second location i.e. At the Circuit Breaker board with an optional extra panelThe Polarity and Earth Continuity Module can be applied under the Australian Standard Wiring Rules for Pleasure craft section AS3004.2: 2008 S5.5.3.2 AC. (Protection against reversal of polarity in the supply lead) And The National Standard for commercial vessels NSCV Part C Section 5 Subsection 5B (Electrical) Paragraph 4.7.1.c (Shore Supply) The Surepower PEC Module is manufactured and complies with AS/NZS 3100:2002

terryk
Posts: 320
Joined: Wed Jan 10, 2007 10:37 pm
Location: Gosford

Re: AC grounding plate

Post by terryk » Tue Jul 01, 2014 7:45 pm

Thanks DA, more info to get my head around :!:
cheers
terryk

dennisail
Posts: 61
Joined: Tue Feb 19, 2013 1:42 pm

Re: AC grounding plate

Post by dennisail » Fri Sep 26, 2014 3:28 pm

I cant think of a better way to promote corrosion than connecting shore power to your boat then using a grounding plate.

Use an isolation transformer, or run everything off the inverter and have the charger big enough to handle loads. That will work in most cases where air cons etc aren't being used. That way your boats electrical system will be isolated from the rest of the marina and currents from other sources wont be encouraged to flow through your boat. And fault currents wont be encouraged to flow from electrical faults through your body to the water.

When I looked at the Australian standards a while a go I did not see anything about grounding plates (maybe I did not look hard enough). I did see the mandatory use of RCDs even on inverters!

This makes pretty much no sense at all since the only way you can get shocked with an inverter is to get between the 2 phases, in which case an RCD will do nothing. You can be standing in water and grab a phase and nothing should happen since the output is isolated from earth (or should be, better check your inverter before you try this :lol: ). So an RCD would do nothing again. An RCD will also do nothing on a shore power supply if you get between A and N unless your body is grounded. The difference is current will flow if you get between ground and A on shore power. BTW this only happens because our shore power distribution system is designed this way, there is no magical tendency for electricity to flow to earth.

So what do they make you do? They actually make you create a false earth by creating an MEN link by joining one phase of the inverter to the earth wiring. This then creates all the dangerous situations of shore power where before there were none, just so that an RCD will then work.

The only way this system is safer that then leaving the 2 phases isolated from earth is in case one phase livens up the chassis of one appliance (say the toaster) then the other phase livens up another appliance (say the old metal case drill). THEN you touch BOTH the toaster AND the drill at the same time while they are on! Seems to me the amount of problems it solves is just as bad as how many it creates.

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