Electrical Box Wiring Correct?

[Mrjlh]

Renting a house and noticed many of the florescent lamps glow when off. This tells me there still is a small current flowing. Checked the main circuit box and something just doesn't look right to me. Appears the "Hot" and "Neutral" are reversed. See Photos. Am I correct or is this wiring OK? Haven't checked the wall plugs and switches yet. They just added an A/C and thought maybe they screwed it up but it looks as if this the the way it's always been. Maybe Crosey has a comment. Thanks for any input.

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[InterestedObserver]

Going strictly by the wire colors things are reversed. Line (L) should be the black, switched conductor and neutral (N) should be the white conductor. The circuit breakers should be located in the black conductors. But then no voltage readings, L-L and L-N and L-G (Earth), have been provided for an accurate system analysis.

[Crossy]

Indeed ^^^, you need to verify if the switched conductors are indeed live (despite their being the wrong colour).

Several ways to do this, if you have a neon-screwdriver then it should light up on the common of the MCBs, a multimeter should read about 220V between the same point and earth (a big screwdriver in the ground will be a good enough earth).

Fluorescents glowing when 'off' is invariably caused by the switch being in the neutral rather than the live, this would also apply if you have L & N reversed in your electrical box.

[Mrjlh]

I just confirmed my suspicions, all the switched lamps have a current with the switch off. I used a nifty little device I got stateside. It's called a non-contact Circuit Alert by Gardner Bender. Works on all voltages. Push the button and it "beeps" very slowly but as you approach the circuit being tested it starts beeping more rapidly as you get closer and a led light flashes. I've had electricians here tell me the line was dead but I've proved them wrong every time.

Thanks for the input and your help. I felt there was something wrong and the box just didn't look right. Time to call the house owner. I could but I'm not about to tackle this problem. I'll print out the pictures and give them to the owner.

Thanks again Oh Great Ones!!

[electau]

As Crossy states, the neutrals are switched. Black is the line (active) conductor, white (or grey) is the neutral conductor.

The switching must be in the line (active) conductor. There must be no switch in the neutral conductor unless the line and neutral are switched simultaneously, ie, double pole switching. Switching in the neutral only can cause a hazardous situation.

It is a common electrical defect in Thailand caused by not carrying out polarity tests.

Edited August 22, 2011 by electau

[Mrjlh]

Home owner says he talked to his "experts". They say nothing is wrong. Yet he hasn't even seen the problem himself. It's OK the way it is according to his experts.. Try to educate some some people and the ignorance factor just won't go away. So when he comes over I'll have him change a light that needs fixing. He'll get the same surprise I got!

[elgato]

Indeed ^^^, you need to verify if the switched conductors are indeed live (despite their being the wrong colour).

Several ways to do this, if you have a neon-screwdriver then it should light up on the common of the MCBs, a multimeter should read about 220V between the same point and earth (a big screwdriver in the ground will be a good enough earth).

Fluorescents glowing when 'off' is invariably caused by the switch being in the neutral rather than the live, this would also apply if you have L & N reversed in your electrical box.

I concur with Crossy. Also the previous post to his mentioned the color codes are off which normally isn't a problem if the wrong color "code" is followed through from the box (supply) to the appliance/light (load).

[Artisi]

Indeed ^^^, you need to verify if the switched conductors are indeed live (despite their being the wrong colour).

Several ways to do this, if you have a neon-screwdriver then it should light up on the common of the MCBs, a multimeter should read about 220V between the same point and earth (a big screwdriver in the ground will be a good enough earth).

Fluorescents glowing when 'off' is invariably caused by the switch being in the neutral rather than the live, this would also apply if you have L & N reversed in your electrical box.

Crossy;

any comment on fluoro's "flashing" when switched off, the house we are currently staying in has a flashing fluoro - 1 of a 2 lamp setup, the other fluoro lamp has no ceased to come on (dead I guess) but interestingly the flashing lamp no longer flashes.

[Crossy]

Crossy;

any comment on fluoro's "flashing" when switched off, the house we are currently staying in has a flashing fluoro - 1 of a 2 lamp setup, the other fluoro lamp has no ceased to come on (dead I guess) but interestingly the flashing lamp no longer flashes.

If these are CFLs (Compact Fluorescent Lamps) or fluorescent tubes with electronic ballasts then this is quite common.

It's caused by capacitive leakage in the switch wiring gradually charging up the reservoir capacitor in the ballast, once it reaches sufficient voltage the electronics will briefly fire up the tube, giving a flash every few minutes. This is particularly prevalent in multi-way switching (stairs etc.) with long intermediate runs.

A low wattage conventional lamp in the circuit will be a simple solution, if you don't want another lamp a 0.1uF X Rated 250V AC capacitor across the lamp holder will kill the flashing dead.

Alternatively, you could try more expensive CFLs which often have the additional components built in.

[Artisi]

Crossy;

any comment on fluoro's "flashing" when switched off, the house we are currently staying in has a flashing fluoro - 1 of a 2 lamp setup, the other fluoro lamp has no ceased to come on (dead I guess) but interestingly the flashing lamp no longer flashes.

If these are CFLs (Compact Fluorescent Lamps) or fluorescent tubes with electronic ballasts then this is quite common.

It's caused by capacitive leakage in the switch wiring gradually charging up the reservoir capacitor in the ballast, once it reaches sufficient voltage the electronics will briefly fire up the tube, giving a flash every few minutes. This is particularly prevalent in multi-way switching (stairs etc.) with long intermediate runs.

A low wattage conventional lamp in the circuit will be a simple solution, if you don't want another lamp a 0.1uF X Rated 250V AC capacitor across the lamp holder will kill the flashing dead.

Alternatively, you could try more expensive CFLs which often have the additional components built in.

Thanks for the info, it is as I suspected and your technical description is appreciated.

[Crossy]

To carry on from my previous post, NPE have the requisite capacitor http://www.mynpe.com/more.php?data=136293017410 at the heady price of 2.5 Baht each

If you can't get to an NPE then print the page and take to your local TV repair man, he should have something suitable

[WarpSpeed]

Yep I just made a post regarding this crossing of neutral and line wires when wiring up the panel in another thread, it is a common, dangerous and potentially deadly practice here due to not having a proper ground which would prevent such incompetence from occurring being as they would dead short immediately if they were so wired. Instead now they just shock you by running voltage backwards through switches and the like so that the switch just disconnects the neutral line instead of the power line energizing everything downstream....

[electau]

Yep I just made a post regarding this crossing of neutral and line wires when wiring up the panel in another thread, it is a common, dangerous and potentially deadly practice here due to not having a proper ground which would prevent such incompetence from occurring being as they would dead short immediately if they were so wired. Instead now they just shock you by running voltage backwards through switches and the like so that the switch just disconnects the neutral line instead of the power line energizing everything downstream....

An earthing system will not be affected if the line and neutral are reversed on a TT system as there is no connection between the neutral and main earth.

On an MEN system the neutral is earthed and reversal of the line and neutral will cause the earthing system to rise in potential (voltage). It is limited by an effective main earth and electrode. Automatic disconnection does not occur. This is a potentially hazardous situation.

On a final subcircuit with an MEN system the line and neutral are reversed the neutral will be switched which may cause a hazardous situation as the equipment connected is not isolated from supply if the switch is operated.

A switch must operate in the line conductor only unless the line and neutral are switched simultanously on a final subcircuit from a switchboard.

The problem will not occur if correct polarity tests are carried out initially.

　

[WarpSpeed]

Yep I just made a post regarding this crossing of neutral and line wires when wiring up the panel in another thread, it is a common, dangerous and potentially deadly practice here due to not having a proper ground which would prevent such incompetence from occurring being as they would dead short immediately if they were so wired. Instead now they just shock you by running voltage backwards through switches and the like so that the switch just disconnects the neutral line instead of the power line energizing everything downstream....

An earthing system will not be affected if the line and neutral are reversed on a TT system as there is no connection between the neutral and main earth.

On an MEN system the neutral is earthed and reversal of the line and neutral will cause the earthing system to rise in potential (voltage). It is limited by an effective main earth and electrode. Automatic disconnection does not occur. This is a potentially hazardous situation.

On a final subcircuit with an MEN system the line and neutral are reversed the neutral will be switched which may cause a hazardous situation as the equipment connected is not isolated from supply if the switch is operated.

A switch must operate in the line conductor only unless the line and neutral are switched simultanously on a final subcircuit from a switchboard.

The problem will not occur if correct polarity tests are carried out initially.

　

Yes it will, because the imbeciles here use it as a neutral as it does not distinguish.. The rest of your post is what I posted in the other thread.

Your final line echoes what I said over there too and is the crux of the issue here..

Edited September 12, 2011 by WarpSpeed

[electau]

In reply to post #14.

If correct polarity tests are carried out switching in the neutral conductor only will not occur, as this is part of the testing and verification process when connecting an installation, additions, or repairs to an electrical installation.

1 Visual checks.

2.Earthing.

3.Insulation

4.Polarity tests.

Above are some of the tests required.

If a defect is found it is rectified immediately.

However these tests are not carried out in Thailand so serious defects can and do occur in electrical installations.

An earthing conductor, or a conductor coloured green or green /yellow must never be used as a current carrying conductor in normal operation and a switch must never be connected in an earthing conductor.

　

Edited September 13, 2011 by electau