Brief interruptions to TV when fans or lights are switched

[UniqueWord]

My apologies if this has been addressed before.  I seem to recall a thread about it..  But I have searched thru 13 pages of the Elec Forum, and done searches on almost all the key words in my subject today to no avail.

I have a LG LED TV which has a xformer brick to low power DC.  It's connected to the main supply thru a surge suppressor, possibly of questionable utility.  We recently had the ground floor wiring re-housed, not replaced, due to failure of the false ceiling drywall because of insect damage.  At the same time I had the chance to check the colour coding, which follows no standard.  There are black, blue and green solid 4mm² conductors.  The original wiring was done by a PEA employee in his off time.  The grounding appears to be intact, with phase-neutral at 240V, phase-ground at 240V, and neutral-ground at 0V.  This is the extent of the checks I've been able to make.

We discovered that the MCB for the room that has the TV was only 20A, and were advised to replace it with 32A.

This has not fixed the problem.  I've read elsewhere that this problem may be due to a bad HDMI cable or a bad surge suppressor.  I'd appreciate any insight which you good folks might have.

Cheers, UW.

[KittenKong]

If you cant find what's wrong a simple practical solution may be to buy a computer UPS for around 1500B.

 

https://www.jib.co.th/web/product/readProduct/32823/340/UPS--เครื่องสำรองไฟฟ้า--SYNDOME-ECO-II-600--600-VA-360-WATT-

 

Back in Europe where we often had power cuts and lightning strikes during storms I used to run all my PC and AV equipment off three different UPS devices.

 

Here I just use a UPS for my PC as power cuts are very rare in my condo, and when they happen at all they are usually scheduled in advance by the power company.

 

 

[NCC1701A]

27 minutes ago, UniqueWord said:

I'd appreciate any insight which you good folks might have.

what happens when you remove the surge suppressor? and any extension cords.

 

unplug everything from your tv except power. does the problem still happen?

 

is it easy to move your tv to another room and test there?

 

 

Edited May 12, 2019 by NCC1701A

[donim]

Unfortunately it is hard for me to find out what really happens with your TV.

And all the story about the wiring and breakers, still the question is unclear from the post.

 

But when I saw the title 'Brief interruptions to TV when fans or lights are switched' I decicde to open your thread to see, because I had the same phenomen before. And I will explain what.

 

When watching TV, and anything with a induction load like the ceiling fan or airconditioner has sometimes an weird action when they turned off causing the TV signal from the box being disturbed.

It was an DVB Terrestrial receiver, fed the video signal thru HDMI to the TV.

The result was that the screen became blue (as in -no signal-  blue) and a noise, those black white dots you probably remember from the analog era.

Have to wait 10 seconds and the TV signal was back, or after powering off/standby the receiver.

 

What exactly was the cause is still an mistery. No earth is in the game with the TV and receiver so probably some atmosferic stress for a short while and the hdmi or sat/ant cables were functioning as an antenna to pickup those intrasterrrial form of spikes.

 

It was all gone when an another box came in place

(My puppy ate the remote and I choosed to replace the box anyway)

 

Sounds familair in your situation?

 

 

PS.  The 20amp breaker is good enough for one room, I am using  16amp and 10amp breakers here.

 

Rgds,

[carlyai]

Can you make sure that your TV is not on the same power feed as the lights and fans?
Probably turn off the lights and fans breakers and find a power point that is still live and plug the TV into that.
See what happens when you play with the lights and fans again.

Sent from my SM-J700F using Tapatalk

[longball53098]

I am guessing that it is a shared neutral causing this. Lights may be on one hot and the TV on another hot but they share the same neutral.  ???

[bankruatsteve]

^I was just going to post the same.  In my case, it was a fan that would cause a light to flick but a "borrowed" neutral was the cause.

[longball53098]

Just now, bankruatsteve said:

^I was just going to post the same.  In my case, it was a fan that would cause a light to flick but a "borrowed" neutral was the cause.

Great minds think alike I guess!  ????

[carlyai]

Great minds think alike I guess!  [emoji6]

What about me?

Sent from my SM-J700F using Tapatalk

[donim]

3 hours ago, longball53098 said:

I am guessing that it is a shared neutral causing this. Lights may be on one hot and the TV on another hot but they share the same neutral.  ???

In the electric circuit at home, the neutral is shared in the consumer unit.

Only the live wires go trough these breakers, unless two pole breakers are used for both L and N.

 

 

[bankruatsteve]

5 minutes ago, donim said:

In the electric circuit at home, the neutral is shared in the consumer unit.

Only the live wires go trough these breakers, unless two pole breakers are used for both L and N.

 

 

Individual circuits consist of L and N (yes, L is on a breaker and N's are on a common bar).  A "borrowed" neutral is when the N for one circuit is also connected to N of another circuit.  IE:  Two separate L, but only one N.  This is not allowed per any code.

[Crossy]

14 hours ago, UniqueWord said:

We discovered that the MCB for the room that has the TV was only 20A, and were advised to replace it with 32A.

 

NO!!!

 

20A is the correct breaker for non-fused Thai 16A outlets even if they are on 4mm² cable.

[tjo o tjim]

What inputs do you have to your TV?  Since you have a very solidly grounded power system, i would expect either a switched neutral rather than phase, or a ground loop on your Cable or some other input. 

[Advocate]

Voltage in Thailand is 220 V not 240 V. If you measured 240V something is wrong.

 

The most likely cause is something in your TV. I have a Toshiba TV that occasionally interrupts for a second or two for no apparent reason. I believe the problem is in the TV not anything else. The problem may be triggered by a fluctuation in the mains voltage but its not an electricity supply or wiring problem.

 

The fact that it happens when you switch a fan or a light on may be incidental.

[ross163103]

No help, but I had the same issue--along with others, so had the wiring re-done in my house, same thing as before, no improvement in the television going off when fan switch is turned off. I'm not an electrician but tend to go with the shared neutral issue. Sure wish I could find a western trained electrician in the Chonburi area....the Thais I've had in just don't understand enough about electricity. I've had to explain a few things to them, of course everybody lost face when I did that....oh well.

[Advocate]

42 minutes ago, ross163103 said:

No help, but I had the same issue--along with others, so had the wiring re-done in my house, same thing as before, no improvement in the television going off when fan switch is turned off. I'm not an electrician but tend to go with the shared neutral issue. Sure wish I could find a western trained electrician in the Chonburi area....the Thais I've had in just don't understand enough about electricity. I've had to explain a few things to them, of course everybody lost face when I did that....oh well.

The problem is in your TV not the wiring. If you do a Google search you will see that many people have such problems and there are many causes unrelated to the main power system. There is nothing in switching a fan or light that should affect the TV if it is in good order.

[dotpoom]

I wouldn't understand much about the problem but to get the best help would a little more information about the problem not be a good idea....more than... "brief interuptions"?

[ThaiFelix]

Happens to me if the HDMI cable is touching or too close to a power cable.

[hans christiansen]

On 5/13/2019 at 7:57 AM, longball53098 said:

I am guessing that it is a shared neutral causing this. Lights may be on one hot and the TV on another hot but they share the same neutral.  ???

I think you are right!!!

[rwill]

One thing I would like to add.  The amperage of the breaker is based on the wire size used.  You should not just change to a higher amperage without knowing that the wiring is sized properly for it.  Too much current through an undersized wire can cause a meltdown.  

[The Theory]

On 5/12/2019 at 9:42 PM, UniqueWord said:

This has not fixed the problem.  I've read elsewhere that this problem may be due to a bad HDMI cable or a bad surge suppressor. 

 

May I ask you if you use any TV box ? 

If yes, just disconnect the cables (Coaxial or HDMI or both) from the box to the TV and then try lights or fan while the TV is on and see what happens. Do you still have the same interruption ?

Please let me know the result. 

 

Edited May 19, 2019 by The Theory

[Lickey]

Had a similar prob,start the elec shower & tv would go off for a few seconds,turned out to be a loose conection in the wall plug,worth checking..

[wayned]

3 hours ago, rwill said:

One thing I would like to add.  The amperage of the breaker is based on the wire size used.  You should not just change to a higher amperage without knowing that the wiring is sized properly for it.  Too much current through an undersized wire can cause a meltdown.  

Not only the wire size but the rating of the sockets that the wires are attached to.  Thai sockets are rrated at 16 amps so even if you could run #10 wire the circuit breaker should not be greater than 20 amps.

[sometimewoodworker]

6 hours ago, wayned said:

Not only the wire size but the rating of the sockets that the wires are attached to.  Thai sockets are rrated at 16 amps so even if you could run #10 wire the circuit breaker should not be greater than 20 amps.

Not true. If you run a 6mm sq  circuit you can have a 30A circuit breaker. It is immaterial that no one outlet should draw more than 16A as you are protecting the wiring not the outlet. It is perfectly acceptable in any wiring code to have breakers that exceed socket ratings.

 

UK ring final circuits (though really fun to trouble shoot) run on 2.5mm sq wiring each socket on it is rated at 13A, the correct circuit breaker is 30A. The UK wiring regulations are among the most stringent.

[impulse]

9 minutes ago, sometimewoodworker said:

Not true. If you run a 6mm sq  circuit you can have a 30A circuit breaker. It is immaterial that no one outlet should draw more than 16A as you are protecting the wiring not the outlet. It is perfectly acceptable in any wiring code to have breakers that exceed socket ratings.

 

UK ring final circuits (though really fun to trouble shoot) run on 2.5mm sq wiring each socket on it is rated at 13A, the correct circuit breaker is 30A. The UK wiring regulations are among the most stringent.

 

How do you protect a 2.5mm2 wire with a 30 amp breaker?

 

[Crossy]

11 minutes ago, impulse said:

How do you protect a 2.5mm2 wire with a 30 amp breaker?

 

In the UK by running a ring-final (ring main), essentially two bits of 2.5 in parallel. Appliance cords are protected by the fuse in the plug.

 

Thailand does not have fused plugs so you have to size the breaker so that an appliance fault will open the breaker before the cord catches fire.

 

No way one should go over 20A breaker on a Thai outlet circuit even if it's wired in 4mm².

 

The risk is that in the event of an appliance problem (rat chewed the cord), the breaker won't open before the conflagration gets going.

 

The length of 0.5mm² speaker wire (rated at 3A) on your fan is going to get pretty warm at 35A (and a 30A breaker won't even flinch).

 

[UniqueWord]

Thanks for all your suggestions and speculations.  I can now report on my investigation and eventual correction of the problem.  First a clarification of what I had termed 'brief interruptions'.  Most noticeable on TV images which either pause or cut out for less than 1 second, probably in the 300-700ms range. Audio is interrupted at the same time but it's less noticeable when there is no video present.

My LG TV has only one HDMI input and one USB input.  Because I have a DVD player, I have a HDMI switch which can select one of 3 inputs depending on which one has an active signal.  If more than one is active the highest ranked is selected.  There is a manual push-button to go to the next active one.

Per Crossy's advice the original 20A breaker was put back.  I checked for the fault condition when the TV was playing from the USB input (Kingston Data stick), the Set Top Box (TrueVisions) and the DVD player (Sony Blu-Ray).  The results were:

USB    0 interruptions in 10 events (fan turning OFF)
STB    3 interruptions in 10 events (fan turning OFF)
DVD    3 interruptions in 10 events (fan turning OFF)

Interestingly, the problem did not occur with the fan turning ON at any speed setting.

I had already decided to buy a UPS for the TV, which was a suggestion I received, but these results made me think about the HDMI cable from the switch to the TV.  When I replaced that the problem disappeared completely.  The new HDMI cable is 3 metres long and I only require 1 metre, but that was all I could get.  It cost 350 Baht.

I now have the whole thing supplied from the UPS which works great and we get no more annoying interruptions.

I have no explanation for this except to think of RFI getting into the HDMI cable, but it's a real mystery why it's not deterministic (3 out of 10), and why it doesn't happen when the the fan turns on.   The old cable was the flat ribbon type whereas the new one is in a proper cable and probably shielded.  Also the fan was not that close to the cable, at least 2-3 metres away.

Anyway I hope my experience might be useful for somebody out there.
Cheers, UW.

[Crossy]

2 hours ago, UniqueWord said:

The old cable was the flat ribbon type whereas the new one is in a proper cable and probably shielded.

 

I have an HDMI cable that came with a set-top box with which it works perfectly, it won't work at all going PC to monitor. I have another which only works one way round despite HDMI supposedly being symetrical.

 

Great that you got it sorted.

[robblok]

11 minutes ago, Crossy said:

 

I have an HDMI cable that came with a set-top box with which it works perfectly, it won't work at all going PC to monitor. I have another which only works one way round despite HDMI supposedly being symetrical.

 

Great that you got it sorted.

There are a lot of different HDMI cables for a lot of different prices. I have other problems with cheap HDMI cables. I wont go for the real expensive one but wont go for the cheapest either.

[sometimewoodworker]

22 minutes ago, robblok said:

There are a lot of different HDMI cables for a lot of different prices. I have other problems with cheap HDMI cables. I wont go for the real expensive one but wont go for the cheapest either.

It is not at all uncommon to find an HDMI cable that will work in one situation but not I another, very common in cheap ones, not so usual in more expensive ones.