Bonding N and E killed my suitcase generator

IanR

IanR

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Having followed the threads on bonding inverter generators I bought a separate tail lead and bonded Earth and Neutral in the plug and marked it for Generator only. This appears to be accepted practice on a number of forums including this one.

When I started the Hyundai HY 2000si it ran away at full throttle , I turned it off but it now shows zero output on the AC side and no output LEDs with idle only.

A word to the wise from the experience

check and check again!

Anyone want a nice four stroke engine and a case of bits?
 
IanR said:
Having followed the threads on bonding inverter generators I bought a separate tail lead and bonded Earth and Neutral in the plug and marked it for Generator only. This appears to be accepted practice on a number of forums including this one.

When I started the Hyundai HY 2000si it ran away at full throttle , I turned it off but it now shows zero output on the AC side and no output LEDs with idle only.

A word to the wise from the experience

check and check again!

Anyone want a nice four stroke engine and a case of bits?
Click to expand...

Hi i would be intetested in the motor out of it
 
RichardS said:
I have an earth terminal on the case of my Honda but I've never connected it to anything. I can't see why one would need to.

Richard
Click to expand...

The Hyundai has an earth terminal too. The instruction manual (q.v.) says that the generator should be earthed, using this terminal, if it is used with earthed equipment .

I assume that means if you use 2 wire/ doubly insulated equipment earthing is not necessary

Needless to say I cannot find the version of the manual I was reading this morning. The one I now find just says the generator should be earthed to avoid electric shocks!


Found it page 13 https://hyundaipowerequipment.co.uk...d/?d=0&file=custom/upload/File-1460983261.pdf
 
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VicS said:
The Hyundai has an earth terminal too. The instruction manual (q.v.) says that the generator should be earthed, using this terminal, if it is used with earthed equipment .

I assume that means if you use 2 wire/ doubly insulated equipment earthing is not necessary

Needless to say I cannot find the version of the manual I was reading this morning. The one I now find just says the generator should be earthed to avoid electric shocks!


Found it page 13 https://hyundaipowerequipment.co.uk...d/?d=0&file=custom/upload/File-1460983261.pdf
Click to expand...

I think we have all got bent out of shape on this generator stuff. The way I understand it, if you are on land they say to drive a stake in the ground and earth it. But in effect to join the neutral and earth at the machine? Im with Richard on this one! And joining the earth of the AC system to the negative battery on a boat as Ive seen people in here say!
Stu
 
skipper_stu said:
I think we have all got bent out of shape on this generator stuff. The way I understand it, if you are on land they say to drive a stake in the ground and earth it. But in effect to join the neutral and earth at the machine? Im with Richard on this one! And joining the earth of the AC system to the negative battery on a boat as Ive seen people in here say!
Stu
Click to expand...

Indeed. Vic's manual says the generator should be earthed if it is being used to power equipment which is connected to earth.... But surely on a boat none of the equipment is earthed unless you are connected to shorepower but then you wouldn't be using the generator, of course.

Richard
 
The reason for N-E connection is to give RCCDs a chance to work. It is that bonding that creates a circuit for a conductor to equipment case fault to trip the RCCD.
Now then, in the case where there is no local ground then there is also no path though people for a fault to conduct, so 1 fault wont harm you. 2 faults are likely to cause a current tip to go, so no problem there.
However boats are notoriously wet, or at least damp places, so relying on the insulation of a plastic hull is possibly a bit hopeful.

What is interesting is that there was sufficient energy in a L-E connection to kill the genny, perhaps they are built with 4Vac on the neutral already? Good for using RCCDs to detect a N-E fault in the equipment.
 
RichardS said:
Indeed. Vic's manual says the generator should be earthed if it is being used to power equipment which is connected to earth.... But surely on a boat none of the equipment is earthed unless you are connected to shorepower but then you wouldn't be using the generator, of course.

Richard
Click to expand...

I take what the manual says: "Make sure to ground/earth the generator when the connected appliance is grounded/earthed", to mean equipment with 3 core wiring with which the metal case would normally be connected to the earth wire as opposed to doubly insulated equipment with only 2 core wiring.

I imagine the OP's intention was to emulate normal mains wiring in which the neutral is earthed at source ( eg substation, pole transformer or whatever). Its the earthing that makes the neutral a neutral
I believe it is possible with some generators, possibly the small Hondas ?? but clearly not with Hyundai.

It is probable that the output from the Hyundai has the equivalent of a centre tap earth ie each conductor being 115 volts relative to the earth conductor. (This I believe is common with inverters) Connecting one of those to the earth conductor effectively shorted out one half of the output with disastrous consequences
 
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Vic

With my little honda I connected the neutral to the earth and also to the metal case of the generator which was also connected to and earthing plate connected to the metal mooring jetty below the waterline.

This provided double earth return paths so and live to earth fault outside the generator will have 2 potential routed for the leakage current to flow and tripping the RCD.

This will not do anything to trip the RCD if there is an internal live to earth fault inside the generator itself and no leakage current can flow bypassing the RCD so the RCD will not trip as it is external to the internal generator leakage.
 
Spoke to Genpower the uk agent for Hyundai. The technical expert says that it would be acceptable to bond the earth and neutral in the plug. He considered the failure of the inverter as coincidental " which is unlucky!"

Luckily they are up £300 as I have purchased a replacement inverter module to repair the unit although I am reluctant to repeat the "test" to see if it happens again.

I have just checked the cable tail and it is wired ok as tested with a volt meter.

I guess next time I might try earthing the generator via the tag to the AC earth in the boat, unless of course the experts think this is unsafe.

Thank you to all for your inputs.
 
IanR said:
Spoke to Genpower the uk agent for Hyundai. The technical expert says that it would be acceptable to bond the earth and neutral in the plug. He considered the failure of the inverter as coincidental " which is unlucky!"

Luckily they are up £300 as I have purchased a replacement inverter module to repair the unit although I am reluctant to repeat the "test" to see if it happens again.

I have just checked the cable tail and it is wired ok as tested with a volt meter.

I guess next time I might try earthing the generator via the tag to the AC earth in the boat, unless of course the experts think this is unsafe.

Thank you to all for your inputs.
Click to expand...

Earthing the generator to the AC system earth should cause no problems. but it may not acheive anything worth while without an earthing stake driven into the seabed :) It may connect anyway if you are plugging your genny into the shorepower inlet ....... I would have to check that out to be sure one way or the other , I think.

For an RCD to be fully effective ( that includes the one installed in your shorepower consumer unit if you are connecting that way) the neutral must be bonded to earth at the supply ...... as you intended doing in the first place.

when you have fitted the new gubbins to the genny check for any existing connection between the earth and the two output conductors. If connection found go no further without advice from Hyundai / Genpower.
If no connection found bond the "neutral" to the "earth" with a small fuse. If the fuse does not blow increase it to a sensible value ( 10 amps max) but keep in in the circuit
 
VicS said:
....

For an RCD to be fully effective ( that includes the one installed in your shorepower consumer unit if you are connecting that way) the neutral must be bonded to earth at the supply ........
Click to expand...
That is not exactly true.
The impedance from N to E must be significantly less than required to trip the RCD.
230V/30mA is about 7kohms.
So you could 'bond' using an impedance (and that includes inductance!) of hundreds of ohms without stopping the RCD from being effective.
An RCD will also trip if a floating neutral is shorted to ground.
Although your home Neutral is notionally zero volts, short it to earth and the trip will almost always go.
 
lw395 said:
That is not exactly true.
The impedance from N to E must be significantly less than required to trip the RCD.
230V/30mA is about 7kohms.
So you could 'bond' using an impedance (and that includes inductance!) of hundreds of ohms without stopping the RCD from being effective.
An RCD will also trip if a floating neutral is shorted to ground.
Although your home Neutral is notionally zero volts, short it to earth and the trip will almost always go.
Click to expand...

Perhaps that is what the OP should do ?

I got the idea of a fuse from one of Sterlings instruction sheets
 
lw395 said:
That is not exactly true.
The impedance from N to E must be significantly less than required to trip the RCD.
230V/30mA is about 7kohms.
So you could 'bond' using an impedance (and that includes inductance!) of hundreds of ohms without stopping the RCD from being effective.
An RCD will also trip if a floating neutral is shorted to ground.
Although your home Neutral is notionally zero volts, short it to earth and the trip will almost always go.
Click to expand...

That would reduce the potential to detect and disconnect a circuit with a N - E fault.
 
RichardS said:
I'm pretty sure that those of us who have never earthed their suitcase gennies and lived to tell the tale are all asking "Why bother with all this?"

Richard
Click to expand...

Ahh, that one is easy...
Those who didnt live to tell the tale, err, arent here to tell the tale?

Why bother?
How many times has any electrical installation or equipment you have used had a fault that was only detected due to an earthed supply?
Of those faults, how many would only have shown up when you made contact with the equipment?
The answer is probably none or very few. These faults are, thankfully, rare. But if undetected can be exceedingly painful (I am quite a connoisseur of electric shocks), or even fatal.
 
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