Obvious to many, I’m sure.

[CamperJack]

I have always thought red was positive and black was negative. But I’m half way through installing my Fiamma turbo vent and it has blue and brown wires!

Which is which please?

Thanks in advance!

By the way the hole cutting in the van roof was remarkably easy and it all fits!!

 

[The Old Man]

https://householdquotes.co.uk/british-wiring-colours/

• Blue

This is the neutral wire

• Brown

This is the live wire

• Green & Yellow

This is the earth wire

 

[suavecarve]

bLue goes left and bRown goes right on a plug.

You just need to find out whether the left is positive or negative now !

My first answer on electrical matters on here.

I m with you in that I really dont know !!!

 

[SandraL]

12v continental wiring brown is often ground, so negative. Blue wire positive or live.
Yes it doesnt sound right to me either but my hymer is like this.
Assume fan is 12v.....

 

[Clipgate]

IEC (most of Europe) AC power circuit wiring color codes

Function	label	Color, IEC
Protective earth	PE	green-yellow
Neutral	N	blue
Line, single phase	L	brown

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[peterc10]

https://householdquotes.co.uk/british-wiring-colours/

• Blue

This is the neutral wire

• Brown

This is the live wire

• Green & Yellow

This is the earth wire

That's for 230v AC mains wiring in UK houses only.

But the OP has a 12v DC fan made by an Italian company, so why would they stick to that convention? The 12v wiring for German motorhomes usually use blue to denote positive, so I suspect it is more likely to be that. But my guess is that the instructions that came with the fan will tell you.

 

[Stealaway]

Always test DC 12v circuits. The Germans have a confusing system. Positive is blue in my van.

 

[LesW]

When the colours first started to change I used to think, which colour is nearest to red.. Brown.

It worked for me..

 

[peterc10]

When the colours first started to change I used to think, which colour is nearest to red.. Brown.

It worked for me..

Yes, but that is only for 230v AC, and was the reason that when the colours were changed brown was designated as "live". But in the rest of Europe, were switches operate on both poles, there is no need for them to differentiate between live and neutral in the way that the UK does, where switches are often single pole. And if you think about it brown is a much more neutral colour than blue, so logic says it should be the other way around.

But all irrelevant for a 12v DC system, which is what the OP is working on.

 

[Lenny HB]

Fairly standard in Motorhomes Blue live, Brown negative /ground (logical really brown is the colour of ground ).
Vehicles use brown for ground as well.

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[ctc]

12v continental wiring brown is often ground, so negative. Blue wire positive or live.
Yes it doesnt sound right to me either but my hymer is like this.
Assume fan is 12v.....

If you want to be really pedantic about , Hymer are right, what we call the positive is for the battery wrong. The error was made many years ago and it doesn't matter.

 

[Two on Tour]

The Eura Mobil we had was blue = positive and brown = negative as I found out the first time I went to wire in something without checking with a test meter.

 

[Captain Yoghurtpot]

bLue goes left and bRown goes right on a plug.

You just need to find out whether the left is positive or negative now !

My first answer on electrical matters on here.

I m with you in that I really dont know !!!

Learnt something in the spelling there with bLue and bRown (Left and Right in capitals).
Will be easy explaining to grandkids.
Excellent!

 

[pappajohn]

Get it wrong it'll either blow a fuse or run backwards.

 

[CamperJack]

But my guess is that the instructions that came with the fan will tell you.

That would be too easy...

They don't, that I can see anywhere. Also the wiring diagram just says "fuse". Doesn't bother to give an amps rating.

Yes it is 12V.

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[CamperJack]

Get it wrong it'll either blow a fuse or run backwards.

Just go for it then? Shouldn't break it?

 

[Captain Yoghurtpot]

Learnt something in the spelling there with bLue and bRown (Left and Right in capitals).
Will be easy explaining to grandkids.
Excellent!

For plugs, that is!
All else, I leave well alone and get someone in .

 

[peterc10]

That would be too easy...

They don't, that I can see anywhere. Also the wiring diagram just says "fuse". Doesn't bother to give an amps rating.

Yes it is 12V.

In that case the wire that goes to the fuse is the positive one

 

[CamperJack]

In that case the wire that goes to the fuse is the positive one

Rather stupidly they have both wires running to the fuse. In a black and white diagram too!

 

[peterc10]

Rather stupidly they have both wires running to the fuse. In a black and white diagram too!

View attachment 408379

I assume that the "red" plug can only plug in one way "up". If so it is probable that the connector on the red plug furthest from the white plug should be the positive.

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[CamperJack]

Always test DC 12v circuits. The Germans have a confusing system. Positive is blue in my van.

How do you test it? It's just two wires coming out of a fan. It's not connected to power.

 

[tonyidle]

The blue is +ve and the brown is -ve (or 0v or ground). There is no reason ever to assume low voltage DC wiring has anything to do with mains wiring or it's colour code.

 

[tonyidle]

Always test DC 12v circuits. The Germans have a confusing system. Positive is blue in my van.

The Germans (and most other Continental vans) aren't confusing. They just don't have the weird UK hang-up that tries to equate mains AC with low voltage DC wiring colours.

 

[Jimbohorlicks]

Best to get yourself a multimeter. Cheap and will save all those doubt about wiring. They soon indicate who h is +ve and negative and as a simple check you can use the same 12v settings on a AA battery to check polarity.

 

[Jimbohorlicks]

How do you test it? It's just two wires coming out of a fan. It's not connected to power.

Failing the multimeter check you can always stick your tongue on one of the wires.

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[DBK]

I have always thought red was positive and black was negative. But I’m half way through installing my Fiamma turbo vent and it has blue and brown wires!

Which is which please?

Thanks in advance!

By the way the hole cutting in the van roof was remarkably easy and it all fits!!

As suggested by Jimbohorlicks get a cheap multimeter from somewhere like Toolstation or Screwfix. It will cost around £10 and you can't safely work on your MH without one.

 

[dabhand]

And don’t forget Black Wires Matter! All the negs on my first van were black

 

[tonyidle]

I think maybe the OP was trying to identify the wires coming from the fan rather than those sticking out of the ceiling.

 

[dabhand]

I think it’s been said further back you could just connect it and see what happens, a multimeter would be best though

 

[Two on Tour]

If the fan runs either suck or blow then just wire it up to a 12v battery and if the switch is set to suck and it sucks and the blow, blows then , if not reverse the wiring.