Reverse polarity when using portable genny??

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curlysue

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We have a light that illuminates to warn us when we plug into shore power and there is reverse polarity. Normally if this happens we simply change the wiring in the shore power lead and problem sorted. However, we recently bought a Kipor 2000 portable genny and when we connected it into our shore power socket to top up the batteries the warning light came on, very dimly I might add. OK, we'll change the wiring in the lead as usual......changed the wiring.....same thing........changed back.....same thing.......mmmm.
As I say it was only very dim, but on all the same. The Kipor has a SMART regulator if that means anything, which was on as per the booklet. Anybody got any ideas.
 
The reverse polarity light is between the neutral and earth of your shoreline.
Its designed to show if you connect the shore supply incorrectly due to faulty wiring in the lead or in the marina/on the pontoon.

Your Kipor is very probably a floating earth genny, so you get 115V voltage between live and earth and 115V between neutral and earth. You will see 230V between live and neutral, so you get the desired supply, but it will light your RP light.

Note that your RCD's will not trip if a fault develops when the genny is plugged in.
 
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Because your generator is not earthed to the shorepower earth I think.

The "problem" has been on here before. Maybe you can do some searches and find what was said before
 
Normal.



In a shorepower feed, the neutral is earthed at the distribution transformer (electricity substation).

In most small generators, the alternator is not connected to the frame or earth of the generator, so both live and neutral are floating with respect to earth, hence to dim glow of the reverse polarity light.


In larger generators, or one installed on a boat, the neutral is connected to earth at the alternator , this is exactly the same as a shorepower supply, the only proviso being, the changeover switch between generator & shorepower must switch both live & neutral..


Short answer, nothing to worry about !
 
Check to see if your genny maker allows neutral-earth bonding.
I know it's permitted on the Honda EU10/EU20 series. This stops the RP light coming on and will allow the RCD to trip in the event of earth leakage.
 
Barry Jones said:
Note that your RCD's will not trip if a fault develops when the genny is plugged in.
Click to expand...

No?

RCDs detect an imbalance between the current flowing into the circuit and what flows back out. That's why they have a connection to both live and neutral. They don't have a connection to earth, and as far as I know their mode of operation has nothing to do with earthing.

I'm not an expert though - anyone else care to comment?

Pete
 
prv said:
No?

RCDs detect an imbalance between the current flowing into the circuit and what flows back out. That's why they have a connection to both live and neutral. They don't have a connection to earth, and as far as I know their mode of operation has nothing to do with earthing.

I'm not an expert though - anyone else care to comment?

Pete
Click to expand...

You are right in that they detect an imblance in the current flowing in the live and neutral.

In the normal situation, in your home for example, that imbalance is the result of current flowing through you to earth if you touch the live conductor. The rcd trips at a low enough current and quickly enough to hopefully prevent electrocution.

If one conductor of the generator output is not earthed to form a neutral and the generator earth not connected to the shorepower system earth then there is no return path through you and no imbalance will result so the RCD will not trip.

AFAIK, but check the wiring diagram in the manual, one conductor of the Kipor is earthed to its frame but that may not be connected to an earth conductor in the output cable. To complete the earth bonding it may be necessary to connect the Kipors earth terminal ( which on land should be connected to an earthing stake) to the shore power earth conductor.
 
AFAIK, but check the wiring diagram in the manual, one conductor of the Kipor is earthed to its frame but that may not be connected to an earth conductor in the output cable. To complete the earth bonding it may be necessary to connect the Kipors earth terminal ( which on land should be connected to an earthing stake) to the shore power earth conductor.
Click to expand...
I think thats wrong.. sorry. The output appears to be fully floating
 
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VicS said:
You are right in that they detect an imblance in the current flowing in the live and neutral.

In the normal situation, in your home for example, that imbalance is the result of current flowing through you to earth if you touch the live conductor. The rcd trips at a low enough current and quickly enough to hopefully prevent electrocution.

If one conductor of the generator output is not earthed to form a neutral and the generator earth not connected to the shorepower system earth then there is no return path through you and no imbalance will result so the RCD will not trip.
Click to expand...

So if there's no path through me, do I still get electrocuted?

Pete
 
prv said:
So if there's no path through me, do I still get electrocuted?

Pete
Click to expand...

You get electrocuted if the current can flow from one conductor through you to the other.
A bit like the old tram rails. You get electrocuted if you stand on the rail and also hold the overhead power line.
 
If you get a live-to-case fault on a mains item, you can end up with a boat at mains potential on its earth points.
Fine until you touch the genny with wet hands, after a rain storm etc while holding a piece of metalwork, then you end up with 230V across you.

This is a totally separate issue to holding the live and neutral simultaneously - no RCD will save you from that.
 
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