Portable genny - works OK - but can I use it??

[Richard10002]

Not sure whether this should be a new thread, but that's what I thought best:


Connected the portable genny to the marina input and found that the polarity reversed light was on on the main board. Added my polarity reversing adapter to the cable – NO CHANGE???

Checked all the plugs on all the cables – all fine.

Bit the bullet and turned on the main breaker switch, (and RCD), turned on the AC battery charger, and it started charging at about 10A and 12.9V, (batteries only 20% discharged).

Turned the battery charger off, turned the AC sockets on, and all seemed fine. Plugged my 3 pin AC system tester into an AC socket and, lo and behold, polarity OK, but NO EARTH!

Whilst I am no expert, logic suggests that the polarity reverse sensor on the main board must actually be sensing no earth.

So, can I use the genny to charge the batteries if I stay away from it and the cable whilst it’s running, and leave the AC sockets turned off at the board.

Would it be better to earth it, say to the hull anode, or somewhere else.

Please note, during my various trials above, I kept checking the inverter system, and the polarity is fine, and it is earthed.

So, how can I find where the inverter system is earthed from and to, and could I connect the Genny to the inverter earth system, (where it exits to earth), if I can find it.

Any comments welcomed, although I’m sure there will be a diversity of opinion.

Richard

 

[VicS]

If used on a boat i think the genny "neutral" should be bonded to its "earth" which should also be connected to its casing and the "earth" should be connected to the boat's "earth" system.

Unless the neutral is earthed and the earth system is contiuous your RCD will not give the level of protection it should.

But what would I do .... nothing probably, just use it as it is.

Sorry too confusing, enough earth around to grow a crop of spuds!

 

[Richard10002]

Vic,

I'm pretty sure that the Genny earth is connected to the neutral on the AC socket. There is a green and yellow wire which is connected to the earth, and it dissappears into the casing towards the AC socket - or could it be going elsewhere.

I'm not averse to connecting to the boats' earth if I can find it, but I dont really know what I'm looking for, other than there is a yellow and green wire connected internally to the hull anode bolt - not sure where this comes from, but I guess I could/should try and trace it.

 

[billskip]

Standard PME ( Proctective Multiple Earth ) systems are used in house wireing.

Basicly a house is supplied with a single cable with a steel armour wire covering.

The inner cable is the line and the outer steel wire is the neu/earth.

So therefor your genny COULD supply the line and neu/earth as two wires.
BUT NORMALLY THE 220v OUTLET FROM A genny has a three pin connection (1 line.. 2 Neut... 3 earth

As you are on a boat and I presume you are afloat you can run an earth wire back to the genny from your 220v socket outlets. (if your genny only has 2wire outlets)

You must understand that you should be ok providing you stay on the boat and dont go shore or jump in the water with electrical equipment.

Imho I would NOT connect earth to an electrode on your boat as it will possibly eat the electrode a bit rapid if you have any current leakge to earth. if you wish to drop an old anode on a bit of wire over the side ok, but this may also have an effect on your boat anodes.

Any leakage to earth (normally above 30ma) should trip your RCCD (Residual Current Curcuit Device) on the genny. but if you have say 10/15ma leakage the device will not trip and you will be very quickly eating away your boat anode if conected to them.

Have respect for electricity you cant see it or smell it, but you can definatly feel it!

My best advice to you is get a qualified electrician to Check your installation

 

[billskip]

I dont wish to answer for vic but just in case he has gone for a bevvy,

The wire you can see connected to your hull anode bolt is to ground all the bits of metal work engine tanks etc and is designed to proctec these bits from electrolisis fro the boats 12v supply.

Your shore power line should be three wires and one of them should be connected to you mains earth and batterycharger it battery charger has a metal case.

AS said IMHO I would not connect mains supply to my anode.

 

[cliff]

With the genny switched OFF and nothing connected check for continuity between the "earth" connection on the genny casing, frame, housing and the "earth" connection on the outlet.
Also check between the "earth" connection on the genny casing, frame, housing and the neutral connection in the outlet. This will tell you if the neutral is bonded to the earth connection or not.
--------------------

"Artificial intelligence is no match for natural stupidity"
sailroom <span style="color:red">The place to auction your previously loved boatie bits</span>

 

[Guest]

Cliff beat me to it ... Genny off ... switches off ... meter casing to neutral in socket - if continuity - then genny is neutral to casing earth bonded.

But I also agree with another - bonding the earth to the boat could induce anode consumption ...

I have used my Wolf 800 as is on the boat and got away with it ... in fact like many people - I do not earth stake it when working out on the estate - just carry to point of work ... start and connect up equipment - do job ... stop and go home. No rod in ground etc. Yep - silly me !! Silly most other people as well ....... /forums/images/graemlins/wink.gif

 

[rogerthebodger]

Interesting info on mains earthing for boats here

 

[Guest]

[ QUOTE ]
Interesting info on mains earthing for boats here

[/ QUOTE ]

Interestingly ALSO highlights the SWIMMER scenario !

 

[rogerthebodger]

I was reading charlie wings electrical wiring book the weekend and he has some simular scenario but he and calder say no earth connected shore power at the boat.

IMHO for a swimmer to get a shock or kill the neutral and earth wire to shore power connection must be open circuit. The live must be shorted to the hull or anode bonding and the earth through the water must be high resistance (earth leakage current flow less than 30mA) to prevent the RCD from triping.and if when swimmer touches the shore if the current increased to a combined 30mA the RCD should trip.

IMHO a possible scenario but on a well maintained sustem very unlikly.

These faults could be very easy to pick up with 2 neon lindicaot lamps connected live to earth neutral to earth of with a cheap earth / phase tester like this

 

[VicS]

[ QUOTE ]
he and calder say no earth connected shore power at the boat.


[/ QUOTE ] I dont know how old that advice is but i think the current "best practice" is for the boat to be connected to the shore power earth.
There is going to be some sort of connection via stern gear and anodes and the water anyway so you will not have a situation in which the boat is totally isolated fron the shore earth even if you do not make the connection with the shore power cable.

Regarding swimmers i believe they are at risk in fresh water not salt water because of the conductivity of the two compared with the human body. It requires a fault and a defective RCD though to create the danger in the first place.

However none of this is relevant to the original question!

 

[Richard10002]

[ QUOTE ]

Please note, during my various trials above, I kept checking the inverter system, and the polarity is fine, and it is earthed.

So, how can I find where the inverter system is earthed from and to, and could I connect the Genny to the inverter earth system, (where it exits to earth), if I can find it.



[/ QUOTE ]

Having thought a bit more about this, I looked at the instructions for the inverter, which state that it must be grounded.

Given that the electrical panel, (and the world/earth), doesnt know whether it is being fed by an inverter, or a generater, or shore power, or whatever, and given that the inverter is grounded, surely all the problems being discussed regarding the earthing of the generater are actually in existence due to the earthing of the inverter.

In which case, if I can find where the inverter is earthed to, and earth the genny to the same point, surely I cant cause any worse problems than have been happily existing for years with the inverter?

That's not to say there arent any problems with the earthing of the inverter?

Any thoughts?

 

[Guest]

Any thoughts ...

Yep - I have various books on this subject ... covering both 12 and 240V ... not one agrees with another.

Similar to above thread really !! Seems there is no definitive answer. I have even asked electricians and they don't agree ... OK - domestic house stuff - yes - agree .... Boats ... No.

So what is answer ? Especially when one will quote ex one book ... another will quote ex another book ... etc. etc.

 

[hshaky]

Don't think you should be using Portable genny as it has the wrong sine wave and could damage your battery charger and other bits.

 

[rogerthebodger]

Sorry Vic I did not make my self clear.

The earth line of the boat must be connected to the shore power earth through the shore power connection through a Gal Iso.

This earth connection should not be connected to the earth bonding on the boat.

Internal generated mains power must have the neutral and the earth bonding of the boat connected at the boat.

This implies that the selector switch must also switch the earth of the shore power.

 

[rogerthebodger]

Onboard mains supply.

Generator or invertor the same.

Neutral and case earth connected togerher and to earthing point on boat.

Shore power neutral and earth is connected at substation. Shore power connection must have seperate live neutral and earth.

Earth connected to earth point on boat but the neutral must NOT be connected to earth at boat as it is already connected at substation as above.

ALL IMHO

 

[Richard10002]

[ QUOTE ]
Don't think you should be using Portable genny as it has the wrong sine wave and could damage your battery charger and other bits.

[/ QUOTE ]

Newmar HDM 20/12-40

"Some generators may not provide a perfect sinewave similar to that provided by shore power. As such, a reduction in charger performance may be encountered when switching from shore to ships' power"

 

[Anonymous]

It looks as though your present system with the tester showing 'no earth' is floating - which is one of the safest possible types of system. It in inherently safe and is the same type as used on building sites to reduce the risk of shock.

I suggest you leave it as is until you get tucked up in your winter berth then you can dig out or produce a wiring schematic for your boat.

Try not to be tempted by your natural curiosity to touch live wires /forums/images/graemlins/wink.gif

 

[Anonymous]

[ QUOTE ]
}Neutral and case earth connected togerher and to earthing point on boat.

[/ QUOTE ]If you do this, and use a selector switch to choose 'Shore', 'Generator', 'Invertor', 'Off' then that switch MUST be two pole otherwise you are grounding the local boat earth to the public N and you boat wiring could carry tens or even hundreds of amps under unbalanced fault conditions.

 

[Richard10002]

[ QUOTE ]
Try not to be tempted by your natural curiosity to touch live wires /forums/images/graemlins/wink.gif

[/ QUOTE ]

David,

Thank you and dont worry - I have no natural curiosity to touch live wires - If I intend going near one, it's with a tester, rather than my finger.

BTW - when connected to shore power, there is an earth, but then I guess being connected to the elctric world, rather than floating in the sea, there probably has to be one.

My curiosity is aroused by the fact that the inverter is/must be earthed so, in your terminology, the system is not "floating" when the inverter is on, and is therefore less safe - which it has been for 4 years now.

a schematic - now that's going to be a challenge!

Richard