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Topic Title: Unexpected dimming of lights.
Topic Summary: Why is it happening when the load is removed?
Created On: 22 September 2017 09:43 AM
Status: Read Only
Linear : Threading : Single : Branch
 Unexpected dimming of lights.   - potential - 22 September 2017 09:43 AM  
 Unexpected dimming of lights.   - kellyselectric - 22 September 2017 12:14 PM  
 Unexpected dimming of lights.   - nad - 22 September 2017 01:00 PM  
 Unexpected dimming of lights.   - mapj1 - 23 September 2017 12:15 AM  
 Unexpected dimming of lights.   - potential - 23 September 2017 10:16 AM  
 Unexpected dimming of lights.   - mapj1 - 23 September 2017 12:32 PM  
 Unexpected dimming of lights.   - OlympusMons - 24 September 2017 02:12 PM  
 Unexpected dimming of lights.   - potential - 24 September 2017 05:41 PM  
 Unexpected dimming of lights.   - potential - 24 September 2017 05:44 PM  
 Unexpected dimming of lights.   - MWalker86 - 24 September 2017 11:10 PM  
 Unexpected dimming of lights.   - kellyselectric - 26 September 2017 12:48 PM  
 Unexpected dimming of lights.   - kellyselectric - 05 October 2017 11:12 AM  
 Unexpected dimming of lights.   - alancapon - 24 September 2017 06:11 PM  
 Unexpected dimming of lights.   - kellyselectric - 24 September 2017 07:52 PM  
 Unexpected dimming of lights.   - potential - 05 October 2017 01:57 PM  
 Unexpected dimming of lights.   - potential - 05 October 2017 02:01 PM  
 Unexpected dimming of lights.   - kellyselectric - 05 October 2017 04:41 PM  
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 24 September 2017 11:10 PM
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MWalker86

Posts: 99
Joined: 05 June 2017

Originally posted by: OlympusMons

The shed might be TTd, and not connected to the house earthing, so it might have something to do with earthing.

I am thinking the main house is TNC-S with a broken PEN, so the neutral current is flowing down the bonding, heating up the earthing conductor and raising the voltage on it. When the blower is switched off, the cable cools, the voltage changes and it is this which causes the lights to dim. I am probably completely wrong though.

What does the data plate on the blower say?


This would be more plausible if it wasn't such an instant and brief effect (as described)
 26 September 2017 12:48 PM
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kellyselectric

Posts: 191
Joined: 22 July 2016

BUMP!
 05 October 2017 11:12 AM
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kellyselectric

Posts: 191
Joined: 22 July 2016

So guys am I right in thinking then that the notable dip in lights when something like a 2Kw heater is switched off or when its own thermostat switches it off is simply due to the inductance of the supply lead creating a momentary voltage that pushes against the supply voltage and causes a brief dip? I have noticed this effect is more pronounced with supplys that are a bit weak for instance in a factory I worked in wehad several large ovens and they never made such an effect because we had a big TX just outside in the yard
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