Switch the Load or the Neutral

**HINO** · 20-08-2008, 06:36 PM

Ok all you electrical gurus and wanna be sparkies!

Please settle a question?

A subject of the Queen from the Island nation

who lives in LOS and is building a house and claims to be a trained electrical engineer has told me that in British electrical standards the wiring to a light fixture is done by running the neutral through the switch and the load directly to the light fixture. In other words switching the neutral to get the light to shine.

I am one of those from the break away country 6 or so hours from the Isles

and all I know of the wiring standards in the USA is the supply side load wire is run to the switch and then to the light fixture and the neutral directly to the light. In other words switching the load to get the light to shine.

So, most Brits I know are always right because they say so and I guess this is the case here also?

Someone please teach me the correct method to wire a light fixture?

Thanks I am never too old to learn something new. I know this is LOS and either way works?

**dirtydog** · 20-08-2008, 06:42 PM

Take your choice, if it is likely to get wet, ie bathroom etc then stick the neutral in the switch.

For flourescents chuck the live in the switch otherwise they glow and flicker.

**Thetyim** · 20-08-2008, 06:56 PM

^
Bugger you got there first.

I will now pre-empt the next question.

The switch should be fixed upside down in Thailand so that on is off and off is on
TiT

**DrAndy** · 20-08-2008, 07:17 PM

and should be located behind the door when you open it

**Thetyim** · 20-08-2008, 07:21 PM

^
No.
The switch should be located as close the the light fitting as possible to save 10 baht on the wiring.
Whatever you do don't locate the switch near the door or you will miss out on all the fun of stumbling around the walls when you come back from the pub

**HINO** · 20-08-2008, 07:44 PM

I plead to be an ignoramus,,

the black insulated in your drawing is the load?

**andy55** · 20-08-2008, 07:56 PM

always break the live wire not the neutral

**dirtydog** · 20-08-2008, 08:02 PM

^Trouble with that is that most bathrooms in Thailand are completely wet and often the switch is in the bathroom, yeah I know it's dumb but thats Thailand for you, if thats the case we run the neutral through the switch.

**lom** · 20-08-2008, 08:53 PM

Originally Posted by dirtydog

if thats the case we run the neutral through the switch.

It is still so wrong to do that.
You ALWAYS break the live wire, no exception to that rule. You are allowed to break both live and neutral with a 2-pole switch though.

Breaking only the neutral wire in wet areas is nothing more than creating a false impression of security.
And anyone who can't afford a few hundred bahts extra on a splash-proof installation deserves to get electrocuted.

**highonthai** · 20-08-2008, 10:03 PM

Am I wrong? but, there is no neautral in a 220/240 volt system...

**lom** · 20-08-2008, 10:10 PM

Originally Posted by highonthai

there is no neautral in a 220/240 volt system

There sure is.
The 220 Volt is the phase to neutral voltage in the 380 Volt 3-phase system.

**highonthai** · 20-08-2008, 11:15 PM

Would this be considered the high leg? Of a 3 phase sytem?

**lom** · 21-08-2008, 12:32 AM

No, high leg is only present in a 3-phase delta system.

This is a 3-phase Y-system where all legs are equal.
380 Volts between any phase to phase , 220 Volt between any phase to neutral.

The center of the Y is the neutral point, the outer points are the three phases.
Look at the letter Y and it will all become clear

The distances between the points are directly related to the voltage.

**Tao** · 21-08-2008, 04:34 AM

Originally Posted by DrAndy

and should be located behind the door when you open it

I've got one of those! It's my own fault though as i asked them to change the side that the door opened at the last minute.

**HINO** · 21-08-2008, 07:36 AM

So do I conclude that this fine British gentleman trained as an electrical engineer is quoting standards incorrectly or did I somehow mis-interpret what he said because of a language problem? I know we don't speak the same language.

I would never "break" the neutral in a light circuit even if the switch is in the wet area. They make switches for this purpose. The places I have seen using a switch in the wet area are wired wrong from start to finish so its not just the wet area that are a concern.

**lom** · 21-08-2008, 08:28 AM

Originally Posted by HINO

I would never "break" the neutral in a light circuit even if the switch is in the wet area. They make switches for this purpose. The places I have seen using a switch in the wet area are wired wrong from start to finish so its not just the wet area that are a concern.

Looks like you already know how to do it so why take any notice of the ideas of a
guy from the backward country?

**baldrick** · 21-08-2008, 10:05 AM

and make sure you have correctly installed earth leakage and a real ground stake .

**Marmite the Dog** · 21-08-2008, 11:03 AM

Originally Posted by Thetyim

The switch should be fixed upside down in Thailand so that on is off and off is on

I changed them all in one of my apartments. Easily done and much more sensible. I was going to put proper plug sockets in as well, but never got round to it.

**The_Dude** · 21-08-2008, 01:25 PM

Sounds like this board has a few sparkys!

If you are running electrical in the bathroom or anywhere with potential for electrical shock a GFCI/RCD should be installed. Always switch your hot lead (never the neutral). And, in we pull 2 hots a neutral with ground wire as per NEC. In Thailand do as you please is the code evidently!

**DrivingForce** · 21-08-2008, 05:06 PM

^ Beat me to it.

That same sort of famous British electrical engineering was applied to the MG's and the Triumphs too.. Where are they now??

Originally Posted by dirtydog

^Trouble with that is that most bathrooms in Thailand are completely wet and often the switch is in the bathroom, yeah I know it's dumb but thats Thailand for you, if thats the case we run the neutral through the switch.

Should have a GFCI (ground fault circuit interrupter)
This is why other appliances shock you, You can't reverse the polarity like this because it energizes the neutral half of the electrical bar especially when there is no grounds to cause a short circuit..

Originally Posted by highonthai

Am I wrong? but, there is no neutral in a 220/240 volt system...

You're thinking standard American where the voltage is split into 110v sides and too make 220v both sides need to be live without a neutral.

**HINO** · 21-08-2008, 06:51 PM

Originally Posted by lom

Originally Posted by HINO

I would never "break" the neutral in a light circuit even if the switch is in the wet area. They make switches for this purpose. The places I have seen using a switch in the wet area are wired wrong from start to finish so its not just the wet area that are a concern.

Looks like you already know how to do it so why take any notice of the ideas of a
guy from the backward country?

I only know the Gent in a hopefully friendly sort of way and we've never tipped a pint together. We discuss his house building and I ask a lot of questions. When we talked about his electrics and he quoted me this British reg about lights and switches, who am I to argue? I just responded in the US of A our code would never allow this.

**DrivingForce** · 21-08-2008, 09:32 PM

^ you have to understand the Brits are still trying to grasp this whole electrical concept..

That's also why 2 of their electric F1 concept cars have electrocuted a couple of their mechanics, hence they've had to shelve the idea for now until they fully grasp the concept..

Though there have been a couple of Brits that have answered on here that seem to have some basic concept though, based on their answers..

**andy55** · 21-08-2008, 11:34 PM

well ive been an electrician since 1968 i live in the uk not thailand btw

**andy55** · 23-08-2008, 04:47 AM

the end

god save our gracios queen
long live our gracious queen
god save the queen

dah dah dah dah --
ever victorious
the live to reingh over us
neutral is the foe of ussssss (
god saaaave the queeen

**More Volts Igor** · 28-08-2008, 03:55 PM

I don't believe it is EVER acceptable to break only the neutral.

A neutral switch when ON will have neutral voltage (OV) both sides, BUT when OFF the live voltage will zip through the light bulb and make one switch terminal hot. So, switching the neutral does not make anything safer, wet or dry

It is possible that the OP's friend is referring to the standard UK light wiring technique of running L & N to the ceiling rose and running a dropper down to the switch, rather than supplying power to the switch and having an 'upper' to the rose (as seems to be the Thai way).

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