Why do my lights go dim and then return to normal?

[judder]

I've recently moved into an old house which has less aged wiring. It is a 200 year old country house which was split into three dwelling places back in the 50s.

The fuse box is quite new and the cables I have seen look fine. However, occasionally the lights in the whole house will go dim for a few minutes and then return to normal brightness. Sometimes, the dimming is accompanied by a clanking noise from somewhere in the bowels of the house, though this may just be coincidence (we also have very high water pressure and experience quite a lot of noisy pipes as a result).

It affects the lights in the lighting ring as well as lamps plugged into the mains. No other electrical appliances show any similar effects.

If anyone could suggest what might be going on I'd be very grateful.

Thank you.

 

[flameport]

Usually it is caused by heavy loads switching on either in your property or nearby ones. Are there any factories or other industrial premises nearby? Do you or your neighbours have electric heating?

If you are a long way from the substation/transformer, the effect will be worse.

The other possibility is a fault with the supply (loose connections typically), either in your property or elsewhere.

 

[bernardgreen]

The clanking noise suggests a motor with a high start up current is switching on. That will dim the lights.

Could be a large fridge or freezer, large central heating pump or maybe a pumped sewage system.

 

[Aragorn84]

For a few minutes though?

The lights in here dim momentarily when you fire up the electric shower, but they dont stay dim...

I would imagine if they're staying dim it suggests theres a voltage drop in the supply somewhere, which might suggest faulty or undersized cabling somewhere.

A big voltage drop can also mean lots of heat generated, so its probably wise to try and trace it down.

 

[Dusklights]

[ so its probably wise to try and trace it down.[/quote]

I would suggest that the first thing to do is to see whether this problem is within your house or not. If you have the knowledge and are competant to do so try to meter the electricity coming into your house. this could tell you if the problem lies with the provider or not

 

[Aragorn84]

Or it could lie in the way the supply has been split from the original into the 3 seperate dwellings...

Perhaps chatting to the neighbours to see if they get similar voltage drops would be a good start?