Dual Wires Lighting Up in Wall Lamps: Phase & Neutral Wiring in 1960s Apartment Block

I have a question about a strange situation that I noticed by chance in all the wall lamps in the apartment.
Well, to each of them there are two wires, i.e. there should be phase and neutral.
However, when the switch is off, a test tube (usual in a screwdriver) lights up in both wires.
However, when I turn on the "one phase" switch, it disappears and zero appears (I think), anyway everything works normally.
The apartment is in a block from the 60's.
Does any of you dear club members know what it could be?

Thanks in advance for your answer.

it seems that the phase wire goes to the bulb permanently and the neutral wire is disconnected - unscrew the bulb and check if the test tube is lit on both

the switch supports only one wire so you connect either phase or neutral to it and it breaks the phase (or neutral) circuit

correctly, there should be a phase on the switch and a permanent zero on the bulb

For sure, the switch disconnects the zero, and the phase is "on the lamp" all the time
The tester shines on both contacts because the phase, through the filament of the bulb, also appears on the other contact.
You would have to get to the cans, which are probably above the light switch and replace it there.
The most important thing is that you know that such a thing occurs, if someone is going to do something with the lamps, warn about this fact! But it's best to get it right.
Regards
Raphael

Mariuszczs wrote:

correctly, there should be a phase on the switch and a permanent zero on the bulb

Not "rather" but it should be - the phase wire is to be disconnected by the switch and the neutral wire goes directly to the device (lamp). It is also worth adding that the phase wire in the lamp should be connected to the foot of the lamp from neutral to the thread for safety reasons.

If it is only a lighting circuit, no sockets are connected, then it is easier to change the order of the wires at the fuse box, but this must be carefully checked so that no phase appears on the protective contact in case of zeroing.

golonka wrote:

it is easier to reverse the order of the wires at the fuse box

First you need to check where the error is made and fix it there.
After the above, it can be concluded that you would like to release the blue phase! - I don't know what would be a bigger mistake, the phase on blue or all the time on the lamp ....
Regards
Raphael

Hello. The neon bulbs in the screwdriver are not a reliable tool, they only indicate the presence of some voltage. You need to make a test tube from an E-27 holder, for example chandeliers (bakelite is the safest) and screw in a 100 watt bulb. For example, I have a test tube made of 2 E 14 holders (smaller than the previous ones) connected in series and two bulbs connected to them. In this case, you can also safely check 2 phases. Returning to the merits of the matter, the phase should be on the connection to the switch, but if it is the other way around in the room, nothing is threatened. Regards

After unscrewing the bulb, the test lamp lights up on both contacts, so the phase does not get there through the bulb filament. So I understand that the problem is already in the can, and since it occurs in all rooms, maybe already at the counter

Do the switches have LED or neon lights?

rafin211 - Read this topic - it should explain a lot... link

Ps. The neon lamp is a poor "indicator" of voltage and it seems that the previous speakers are right - the switch disconnects the zero, not the phase.

Such symptoms clearly indicate placing the switch in the neutral conductor, which is a cardinal violation of safety rules, but years ago it depended only on the degree of sobriety of the fitters. Under no circumstances can the installation be operated safely with such a connection. The circuit breaker must! disconnect phase, neutral always! must be connected! These are elementary security conditions in a two-wire network, where the protective conductor is the neutral conductor. Other conditions are in new installations, but this post is not about that. However, please watch out for the uninformed and therefore dangerous guy with the light bulb - let him check with the light bulb, where is the phase and where is zero!, I wish you success and few injuries! And in the socket - theoretically - phase on the left, zero on the right. Here it is no longer important if we do not use a protective conductor.

kofman wrote:

However, please watch out for the uninformed and therefore dangerous guy with the bulb - let him check with the bulb himself, where is the phase and where is zero!, I wish you success and few injuries!

I use a light bulb tester as described by my friend tyht on a daily basis and I do not consider myself uninformed and even more dangerous if you know how to use it, of course in combination with other indicators, including a neon tester, it is a sure tool. At the author of the topic, the neon light shines on both wires from the wall lamp, the bulb is unscrewed, the switch is off, why this is happening, I will not explain, having the above-mentioned "bulbs" and a neon tester, I know in a few seconds which wire is "full phase".

Do both "phases" shine with a test tube differently, or one can be brighter than the other ?

It seems to me that "both phases" shine the same, at least I don't see a difference.
Today I checked the lighting in the bathroom and of course it's the same, with the switch off and the bulb unscrewed, the phase is on both. When turned on, it disappears on the blue wire

Raphael

In my opinion, the topic is exhausted - what is important has been written, and any further steps should be carried out by an electrician. closing.
[Acres]