Polarity Question (1 Viewer)

[Dave and Ginny]

Hi all,

I adding an additional CBE socket on my 2004 Hymer Starline 680. In doing so I’ve discovered that the 230v sockets are wired Blue to Live and Brown to Neutral. I know the 12 volt system is wired about face (red neutral black live) but wasn’t expecting to get it on the mains side.

Is it the norm or has someone got it wrong?

Cheers Dave

 

[Lenny HB]

Continentals don't differentiate between live and neutral as they use double switched MCB's, & sockets or unswitched sockets. However, if the van has been converted to UK sockets they should be wired correctly.

I have had 3 Hymers a 2008 (UK sockets), 2014 & 2017 (both continental sockets) all wired correctly.

 

[63720]

Brown is live, blue is not, yellow and green earths the lot ?

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[Rodders1234]

I have B544 with continental sockets - what would the effect be if they were wired the wrong way and how can I check? Electrics is not my bag.

I use adapters for UK appliances and all works fine. Is it a simple job to replace the continental sockets?

 

[Lenny HB]

I have B544 with continental sockets - what would the effect be if they were wired the wrong way and how can I check? Electrics is not my bag.

I use adapters for UK appliances and all works fine. Is it a simple job to replace the continental sockets?

As they are unswitched sockets to disconnect you have to pull the plug out which obviously disconnects both poles so it doesn't matter if the supply is revered, also you are protected by an RCD.
Normally with Hymer wiring the sockets are all wired the same. If you are worried you could check with a mains socket tester and with adaptors you can just turn them up the other way. If you were using continental plugs you wouldn't know anyway.

Easy to change the sockets, take the chrome bezel off unscrew the socket insert and replace, you can't use the socket cover with UK sockets.

Even easier do what we do, change the plugs on the appliances.

 

[WESTY66]

Even easier do what we do, change the plugs on the appliances.

Love it!! I’d have never thought of that

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[Off da Grid]

It does matter if the wires are reversed on U.K. appliances.
Not wanting to scare you but.
The reason being the live wire to the appliance will go through the switch and possibly any safety devices to prevent electric shock such as fuses or overload cut outs, on the device.
If the wires are reversed even if the safety devices have tripped the appliance could still be in a condition where you could still get a lethal shock.

 

[Rodders1234]

Thank You for your help Lenny. Only owned the MH for 12 months. Recently had a habitation service and I later noticed on the 230v check there was a bracketed comment ‘reversed’.

Everything works ok and I guess it must be safe otherwise they would have said somethin At the garage. Thinking about it there is not much we plug in, bluetooth speaker, phone chargers and low watt heater in the winter to top up the truma for faster heating when we get in.

It is just one of those niggling topics that I don’t undertand

Thanks again as your comments are reassuring.

 

[Rodders1234]

Just seen ‘off the grids’ comment. I think I will speak to the garage that did my habitation service to be sure.

All too complicated for me.

Thanks

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[thebriars]

It does matter if the wires are reversed on U.K. appliances.
Not wanting to scare you but.
The reason being the live wire to the appliance will go through the switch and possibly any safety devices to prevent electric shock such as fuses or overload cut outs, on the device.
If the wires are reversed even if the safety devices have tripped the appliance could still be in a condition where you could still get a lethal shock.

Not true. In a modern motorhome it is the RCD in the consumer unit which will prevent a lethal shock, and that is not polarity dependent.

 

[bigtwin]

It does matter if the wires are reversed on U.K. appliances.
Not wanting to scare you but.
The reason being the live wire to the appliance will go through the switch and possibly any safety devices to prevent electric shock such as fuses or overload cut outs, on the device.
If the wires are reversed even if the safety devices have tripped the appliance could still be in a condition where you could still get a lethal shock.

If folks dont understand the basics of electricity, should they really be inserting metal prongs into a toaster, or taking the covers off appliances while still connected to a potentially live socket?

That is the only way they would be exposed to a live conductor with a ‘reversed polarity’ scenario.

Common sense tells you that you should isolate the electrical supply before delving into appliances whether the L and N lines are transposed or not.

Ian

 

[bigtwin]

Just seen ‘off the grids’ comment. I think I will speak to the garage that did my habitation service to be sure.

All too complicated for me.

Thanks

You have nothing to worry about, there is no need to spend money at a garage. See other comments in this thread.

Ian

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[Off da Grid]

My comment was not only related to the use in vehicle but an rcd will do the job of keeping you safe.
But RCD’s do fail or get stuck in the on position.
When was the last time you tested yours, should be done occasionally by pressing the test button.

 

[thebriars]

My comment was not only related to the use in vehicle but an rcd will do the job of keeping you safe.
But RCD’s do fail or get stuck in the on position.
When was the last time you tested yours, should be done occasionally by pressing the test button.

It might surprise you that you can get RCDs in domestic consumer units too these days. Only been around in one form or another for some 60+ years.

When did I last test mine in the home? Yesterday actually. The motorhome is in storage at the moment and storage is closed.

As for switches on the sockets, like almost all motorhomes, there are none, in the house they are all double pole.

Even so, except in extremely rare occasions the only way you can get a lethal shock in a reverse polarity situation it to take the appliance apart whilst still plugged in, unless it is something like a toaster where you stick a metal object in.

 

[63720]

If polarity doesn't matter why do we colour code the wiring?

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[Lenny HB]

Recently had a habitation service and I later noticed on the 230v check there was a bracketed comment ‘reversed’.

Obviously haven't a clue as you can put a continental plug in either way round.

 

[xsparks]

Switches on 13a sockets in the home are single pole unless otherwise marked.

 

[pappajohn]

If polarity doesn't matter why do we colour code the wiring?

Because our regs are so antiquated.
Reverse polarity is not acceptable in the UK but the wires must still be identified by colour so every accessory is positive wired throughout. Functionally, the colour doesn't make any difference.
A two way switch is different again... Red, blue and yellow (old colours) ..Brown blue grey (new colours) All three are Pos depending how the switch is swiched so conductors still have to be identified at each end to wire correctly or the switch won't work.
Why do Europeans colour code their wiring then ignore polarity.

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[DBK]

If polarity doesn't matter why do we colour code the wiring?

Because in the UK we use fused plugs with the fuse on the live wire. The fuse will blow if the live is shorted to earth or neutral.

Most other countries don't seem to use fused plugs but have the protection on the supply side covering both live and neutral and don't need fuses. Modern UK houses should have the same now but older ones probably won't.

 

[Lenny HB]

Switches on 13a sockets in the home are single pole unless otherwise marked.

Loads of socket manufacturers supply double pole switched sockets they are not marked. Some of the ones that are double pole, Volex, MEM, Contactum.

 

[xsparks]

Loads of socket manufacturers supply double pole switched sockets they are not marked. Some of the ones that are double pole, Volex, MEM, Contactum.

In this case I stand corrected but I would suggest that you ere on the side of safety. I have installed some modern sockets with USB charging points and they definitely are not double pole switched. If you feel inclined to work on electrical equipment it would be better to switch of the mains at the distribution board / fuse board as this has a double pole switch. If working on a motorhome its best to disconnect the mains lead for your own safety. There are some occasions when you need the mains connected to locate a fault but if your not competent you should leave this to a capable person.

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[Odd job]

My comment was not only related to the use in vehicle but an rcd will do the job of keeping you safe.
But RCD’s do fail or get stuck in the on position.
When was the last time you tested yours, should be done occasionally by pressing the test button.

When I was working I did a lot of RCD tests, many failed, nobody ever tests them every month as we should, including me

 

[bigtwin]

In this case I stand corrected but I would suggest that you ere on the side of safety. I have installed some modern sockets with USB charging points and they definitely are not double pole switched. If you feel inclined to work on electrical equipment it would be better to switch of the mains at the distribution board / fuse board as this has a double pole switch. If working on a motorhome its best to disconnect the mains lead for your own safety. There are some occasions when you need the mains connected to locate a fault but if your not competent you should leave this to a capable person.

In summary:

If you know what you’re doing and need to take the covers off anything, isolate the a.c. supply.

If you don’t know what you’re doing, don’t take the effing covers off!

In either case, it matters not a jot if the L and N are transposed!

Ian

 

[thebriars]

Switches on 13a sockets in the home are single pole unless otherwise marked.

Not true. For example, all mine are double pole, certainly no markings on the outside.

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[thebriars]

In this case I stand corrected but I would suggest that you ere on the side of safety. I have installed some modern sockets with USB charging points and they definitely are not double pole switched.

Easy enough to get these with double pole switches. For example:

https://www.screwfix.com/p/13a-2-gang-dp-switched-socket-2-1a-2-outlet-usb-charger-white/9272j

https://www.screwfix.com/p/mk-logic...ed-socket-2a-2-outlet-usb-charger-white/5541x

 

[xsparks]

What I perhaps should have said it's not safe to assume that an item is double pole. If someone needs to know the reason why reverse polarity is a problem with with our system of single pole protection then it's probably safe to assume they won't recognise the difference between sockets.