TV signal dips when electric shower is turned on

[Alfie25]

I've got a 9.5kW electric shower, and when it is turned on there's always been a very slight dip in the lighting (same happens when hoover is powered on). This was apparent in my last house too so I presumed it was just the power being drawn and wasn't unusual. However, I've now noticed that when the shower is turned on or off, the TV (Freeview through an aerial) sometimes flickers off just for a couple of seconds, screen goes black (sometimes says 'bad signal') and then comes back on ok. Occasionally it just pixelates a bit and doesnt go completely off. I've lived here a couple of years and this problem has probably always been apparent, it's just recently my partner is showering when I'm watching TV so I now notice it!

I've read about people who've had problems with interference on their TV when the shower is on, however my problem is different. There's no interference when the shower is on, just a drop in signal when the the shower is turned on or off. What's likely to be at fault? Wiring? Consumer unit? TV aerial cabling?

 

[flyingsparks]

Have you got a tv booster in the loft fed off the shower circuit by any chance?

 

[Alfie25]

Nope. The shower is on its own circuit and no booster on it.

 

[Taylortwocities]

What sort of electricity supply do you have.

I mean, is it an underground cable, or is it on overhead cables?

 

[winston1]

As you turn on or off the shower a spark is generated at the switch. A spark produces a short burst of radio interference which shows up like this. Same thing often happens with thermostats on fridges or central heating.

Are you using an indoor aerial? A good aerial on the roof with good quality double screened coax cable should solve it if so.

 

[Alfie25]

Hello... in response to the questions, the electricity supply is underground cable.

The aerial is roof mounted, however it does look rather aged. Are you saying if the signal is weak (or aerial/cabling old) then it is more susceptible to this interference from the shower? Also which switch is this spark generated at? Do you mean on the actual shower unit itself?

 

[winston1]

The aerial is roof mounted, however it does look rather aged. Are you saying if the signal is weak (or aerial/cabling old) then it is more susceptible to this interference from the shower? Also which switch is this spark generated at? Do you mean on the actual shower unit itself?

Weak signals, old poorly screened aerial cable all contribute. The spark is generated in the shower switch. It may be possible to fit a suppressor there.

 

[Alfie25]

Does the proximity of the TV coax cable to the shower play a part? The cable comes in under a roof tile then is split - 1 way down a cavity wall to a TV socket in the living room and the other way through the ceiling to a bedroom. This is routed a couple of metres away from the shower cabling.

 

[ekmdgrf]

http://en.wikipedia.org/wiki/Faraday_cage

Just line the walls, floor, ceiling and door of the bathroom with tin foil. Don't forget to earth it.

Better still would be to place the television, Freeview box and antenna system inside a Faraday Cage. It will improve the quality of the output by orders of magnitude.

 

[stillp]

Could just be that the voltage drop that makes the lights flicker is more than the TV is comfortable with. Is it a decent make or a cheapo? You say the hoover also makes the lights flicker. Does it also affect the TV?

 

[winston1]

Does the proximity of the TV coax cable to the shower play a part? The cable comes in under a roof tile then is split - 1 way down a cavity wall to a TV socket in the living room and the other way through the ceiling to a bedroom. This is routed a couple of metres away from the shower cabling.

If it is poor quality coax, yes. Is the splitter a plastic Y type or a fully screened metal one? The plastic ones let in interference. Also is the wall plate fully screened or the saddle and clamp type? Saddle and clamp types also let in interference. Also the flylead from the wall plate to the TV needs to be good quality.

 

[ekmdgrf]

Could just be that the voltage drop that makes the lights flicker is more than the TV is comfortable with. Is it a decent make or a cheapo? You say the hoover also makes the lights flicker. Does it also affect the TV?

The OPs description was of the TV picture pixelating or the Freeview box outputting the message "lost signal". So it does sound more like interfearence through the antenna than the voltage drop upsetting it. The Freeview box will have a SMPSU, the voltage tolerances on those things are wider than the English channel and they also have some serious capacitors in them, so they should be able to survive a short voltage drop.

 

[Lectrician]

The aerial is roof mounted, however it does look rather aged. Are you saying if the signal is weak (or aerial/cabling old) then it is more susceptible to this interference from the shower? Also which switch is this spark generated at? Do you mean on the actual shower unit itself?

Weak signals, old poorly screened aerial cable all contribute. The spark is generated in the shower switch. It may be possible to fit a suppressor there.

The spark would be where ever open circuited the the shower UNDER LOAD. Usually for interference to occur, you need a dodgy slow switch. This is more than likely in the shower itself. It could be the small micro switches in the shower which are operated by the flow control.

 

[Alfie25]

If it is poor quality coax, yes. Is the splitter a plastic Y type or a fully screened metal one? The plastic ones let in interference. Also is the wall plate fully screened or the saddle and clamp type? Saddle and clamp types also let in interference. Also the flylead from the wall plate to the TV needs to be good quality.

Can you explain saddle and clamp vs fully screened please. I presume you mean how the coax is connected to the socket? I guess I'd have to remove it and have a look. In terms of replacement, if it doesn't say screened then is it just saddle and clamp like this one?

http://www.screwfix.com/p/lap-1-gang-coaxial-socket-white/25407

The downstairs TV uses the wall socket. The upstairs one has the coax going straight into the back of it and both experience the problem. I am planning on getting a guy out to fit a new aerial. What's the best way of going forward, bearing in mind I need to run 2 TVs. I dont want any amplified masts, just a simple installation.

I'm thinking 1 good quality aerial with new coax into loft then split with a screened metal splitter, new coax down cavity to downstairs wall socket, replace the wall plate with a screened one. Replace existing coax cable to upstairs bedroom. I'm hoping a fitter would be OK with that - most I've seen seem to just run the cables externally, or fit 1 aerial per connection required.

 

[stillp]

Could just be that the voltage drop that makes the lights flicker is more than the TV is comfortable with. Is it a decent make or a cheapo? You say the hoover also makes the lights flicker. Does it also affect the TV?

The OPs description was of the TV picture pixelating or the Freeview box outputting the message "lost signal". So it does sound more like interfearence through the antenna than the voltage drop upsetting it. The Freeview box will have a SMPSU, the voltage tolerances on those things are wider than the English channel and they also have some serious capacitors in them, so they should be able to survive a short voltage drop.

You could be right, hence my question about the vacuum cleaner. Some of the cheaper TVs, as well as Freeview boxes, are rather sensitive to input voltage, and if the signal is already weak a dropin supply voltage could be enough to give the symptomes described.