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Live - Neutral Reversed

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I have a 1000w inverter from Maplins fitted in the boat, after reading on here about using socket testers to check if the wiring is correct i plugged one into the inverter and got the above error. I select where the power comes from by using a lead and 3 pin plug from the RCD and plug that into the inverter or another 3 pin socket that is connected to the shore power connector.

 

I was thinking of fitting a 3 pin socket next to the inverter and wired to the inverter with the leads reversed to give the correct polarity. is this a bad idea.

 

Thanks for any input

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is this a bad idea.

 

 

 

Yes.

 

Sort out the problem do not cause another, possibly dangerous one.

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If it is a Maplin modified sine wave inverter, (maybe it is actually a badged Nikkai one, or similar?"), then in my experience they do not come with the "mains" 230V Neutral bonded to Earth. This is required for safe installation in a boat, if you want your RCD to trip correctly in certain fault conditions.

 

These Maplin inverters should only be used on a permanent boat installation, if the missing Earth to Neutral bond is added. However not all inverters that lack it can be so modified, I think, so making that modification requires quite a bit of research, (there are previous threads about this). Not a good idea unless you fully understand the possible issues.

 

I'm struggling to see a basic mains tester plug giving you reliable information in such circumstances, as I think either what should be "live" or what should be "neutral" will probably both be at a floating voltage relative to Earth, but that isn't a fault condition, it is you possibly using an inverter not suitable to your application.

 

With this degree of uncertainty, I would say reversing the supposed Live and Neutral from the inverter is a very bad idea.

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In other european countries houses are wired for 2 pin plugs. This means you don't know which side of the plug is live, but it still works. One day the live wire is live but another day the neutral wire is the live. I'm sure the EU would have stopped that if it was a big safety problem.

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In other european countries houses are wired for 2 pin plugs. This means you don't know which side of the plug is live, but it still works. One day the live wire is live but another day the neutral wire is the live. I'm sure the EU would have stopped that if it was a big safety problem.

 

Are you saying the polarity of the grid changes? Isn't it just a question of plugging in the appliance either way around, so it doesn't matter that of two different appliances, might be back to front?

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I had a Sterling inverter whose live and neutral were reversed. Its built-in RCD would of course only work if the neutral-earth bonding link was present, but because of the reversal that actually ensured that the live was bonded to earth and the neutral was at 230v relative to earth. What made that particularly unsafe was that every wall socket and every light, which all have single pole switches, became live throughout when it was switched off; or similarly if any breaker should trip or if any plug's fuse should blow.

 

Yes I could have bodged it by swapping the inverter's live and neutral output connection. Suppose at a later date, somebody else had noticed that the wires were "the wrong way round" and had corrected the mistake, or perhaps the inverter were to be replaced by another whose output was correct? In either case the system would then have been restored to a potentially lethal state. The only correct solution is to fix things properly.

 

Sterling tried to convince me that mine was "only a little bit unsafe" because it was "only an inverter". I countered that they would hear from my executors if I was "only a little bit dead" after touching a live wire, and they agreed to repair it.

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If it is a Maplin modified sine wave inverter, (maybe it is actually a badged Nikkai one, or similar?"), then in my experience they do not come with the "mains" 230V Neutral bonded to Earth. This is required for safe installation in a boat, if you want your RCD to trip correctly in certain fault conditions.

 

These Maplin inverters should only be used on a permanent boat installation, if the missing Earth to Neutral bond is added. However not all inverters that lack it can be so modified, I think, so making that modification requires quite a bit of research, (there are previous threads about this). Not a good idea unless you fully understand the possible issues.

 

I'm struggling to see a basic mains tester plug giving you reliable information in such circumstances, as I think either what should be "live" or what should be "neutral" will probably both be at a floating voltage relative to Earth, but that isn't a fault condition, it is you possibly using an inverter not suitable to your application.

 

With this degree of uncertainty, I would say reversing the supposed Live and Neutral from the inverter is a very bad idea.

Thanks for the replies

Could you recommend a inverter that does not cost a fortune as the boat is only used for holidays.

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I think its a case of buying any cheap one but properly testing it to determine if its safe to use, ie RCD will trip in a fault condition and there's no danger of eletrocution from it.

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Thanks for the replies

Could you recommend a inverter that does not cost a fortune as the boat is only used for holidays.

 

 

The trouble is, the electricity doesn't know or care if it is only used for holidays.

 

If the inverter is safe and fit for the purpose its being used for, then the amount of use it gets doesn't really come into it. Other than the tendency of cheap kit to die sooner, perhaps.

 

MtB

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Thanks for the replies

Could you recommend a inverter that does not cost a fortune as the boat is only used for holidays.

 

So - when you die you will 'die happy' because you were on holiday.

 

Compromise on paint, compromise on cupboard space, compromise on engine but NEVER compromise on safety !!!!

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The trouble is, the electricity doesn't know or care if it is only used for holidays.

 

If the inverter is safe and fit for the purpose its being used for, then the amount of use it gets doesn't really come into it. Other than the tendency of cheap kit to die sooner, perhaps.

 

MtB

 

^^ What he said

 

 

So - when you die you will 'die happy' because you were on holiday.

 

Compromise on paint, compromise on cupboard space, compromise on engine but NEVER compromise on safety !!!!

 

^^ and what he said.

 

However, if it's a holiday boat, do you really need an inverter? We have one, but it is pretty well never used.

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However, if it's a holiday boat, do you really need an inverter? We have one, but it is pretty well never used.

 

yes I was thinking that too.

 

About the only thing I use my inverter for is charging my razor. Everything else can be done with 12v, one way or another.

 

 

MtB

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^^ What he said

 

 

^^ and what he said.

 

However, if it's a holiday boat, do you really need an inverter? We have one, but it is pretty well never used.

It has a 240v fridge and tv.

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The vast majority of inverter installations are safe, that's all the OP wants!

 

I'm not actually convinced this is true.

 

I think a lot of people just buy one from Maplin, Argos, Sterling (or whatever) and wire it in - hopefully they have an RCD, but I wouldn't always guarantee it!

 

They probably have little idea whether everything that should be protecting them actually is.

 

Admittedly accidents are doubtless very rare, but this is surely far more to do with the installation never being presented with a potentially dangerous situation to deal with, than the fact it is actually capable of doing so, should that condition arise.

 

How often, for example, does a live cable get chafed through against a metal edge? In normal situations, probably almost never, but it is still sensible to know you are protected should something unlikely like that occur

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Of all the diy inverter installations that I've seen I reckon that less than 1 in 10 is properly and safely connected with earth/neutral bonding, a good earth to the hull, and a functioning RCD. Often it takes only minutes to fix the problems with a short bit of green/yellow wire.

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Well just putting the other side of the picture, loads of houses including all the ones I have ever lived in, don't have RCDs. I think if you were to assess the cause of the OP's life terminating (as it will at some point), the probability of it being due to a shock from his inverter setup is very small.

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Of all the diy inverter installations that I've seen I reckon that less than 1 in 10 is properly and safely connected with earth/neutral bonding, a good earth to the hull, and a functioning RCD. Often it takes only minutes to fix the problems with a short bit of green/yellow wire.

 

You must admit that seeing the neutral connected to the earth doesn't look right to the average person. You wouldn't wire a 13 amp plug like that.

 

I saw my inverter wired with earth and neutral connected, and thought it must be wrong. Further research showed it was correct, but it's not exactly intuitive.

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You must admit that seeing the neutral connected to the earth doesn't look right to the average person. You wouldn't wire a 13 amp plug like that.

 

I saw my inverter wired with earth and neutral connected, and thought it must be wrong. Further research showed it was correct, but it's not exactly intuitive.

 

To be clear though, you can't just do this to any inverter that doesn't appear to have it.

 

Gibbo wrote a detailed description as to how you can investigate whether an inverter is already internally earth to neutral bonded, but, more importantly, how you work out whether one can be modified if it isn't.

 

This seems to be the most relevant post.

Edited by alan_fincher

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Well just putting the other side of the picture, loads of houses including all the ones I have ever lived in, don't have RCDs. I think if you were to assess the cause of the OP's life terminating (as it will at some point), the probability of it being due to a shock from his inverter setup is very small.

 

Houses are not made of steel and dropped in a large volume of water, or possibly worse GRP.

They usually also have one power source not 2 or more.

Added: RCD's also provide some protection against fire.

 

For the OP: Using a lead and plug is bad practice, install a saftey switch.

Edited by forsberg

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For the OP: Using a lead and plug is bad practice, install a saftey switch.

 

This always seems a perfectly cost effective and safe way of doing things to me, if you are never going to get near the limits of capability of a plug and socket.

 

Very clear which power source you are using, and a dangling lead confirms you are connected to nothing.

 

Yes, a fancy switch can achieve this, but if you don't use Kilawatts, what is wrong with the simplistic (and cheap) approach?

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At least the plug and socket for selection between two power sources absolutely 100% guarantees a "break before make" connection. I can't see why it should be a problem.

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This always seems a perfectly cost effective and safe way of doing things to me, if you are never going to get near the limits of capability of a plug and socket.

 

Very clear which power source you are using, and a dangling lead confirms you are connected to nothing.

 

Yes, a fancy switch can achieve this, but if you don't use Kilawatts, what is wrong with the simplistic (and cheap) approach?

 

1. No proper earth connection.

2 Wear and tear of leads and sockets

3. No strain reliefs on leads.

4. Swapping leads in the rain

5. The possability that one or more power sources is not properly earthed so the RCD can not trigger.

( The test button on the RCD only checks the RCD internal function, it does not check for missing Earth or N-E bond whithout which the RCD is of no use.)

6.Leads not fused.

7. Inadequate lead gauge

And so on...

 

Ofc some of this can be prevented, still leads are not for permanent use.

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I have a 1000w inverter from Maplins fitted in the boat, after reading on here about using socket testers to check if the wiring is correct i plugged one into the inverter and got the above error. I select where the power comes from by using a lead and 3 pin plug from the RCD and plug that into the inverter or another 3 pin socket that is connected to the shore power connector.

 

I was thinking of fitting a 3 pin socket next to the inverter and wired to the inverter with the leads reversed to give the correct polarity. is this a bad idea.

 

Thanks for any input

 

Would be best to double check with a filament test lamp or suitably skilled eleccy person before proceeding any further.

 

I suspect the Maplins inverter is supplied without NE bonding, maybe the MSW output waveform gives an unexpected tester result with no earth?

 

So does a suitable test lamp illuminate if SAFELY connected between N and E or L and E of the inverter socket?

 

IF neither, then it's lacking an NE bond, and a clearly labelled and suitably wired plug and socket could provide this.

 

Another way to help check the existence of a functioning earth is connect a suitable test lamp between L and E downstream of the RCD.

 

cheers, Pete.

~smpt~

Edited by smileypete

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Well just putting the other side of the picture, loads of houses including all the ones I have ever lived in, don't have RCDs. I think if you were to assess the cause of the OP's life terminating (as it will at some point), the probability of it being due to a shock from his inverter setup is very small.

In addition, of all the shocks I've had so far in my life none has a ) killed me or b ) caused the RCD in the house to trip.

 

I still don't think 240Vac is a Good Thing to have in a boat though...

 

MtB

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