630mA 250 glass Fuses blowing on 3 x halogen ceiling light

Joined
21 Oct 2009
Messages
2
Reaction score
0
Location
London
Country
United Kingdom
Our sitting room ceiling light is a three bulb halogen fitting. Last night they just popped off, so I unscrewed the fitting from the ceiling and removed the fuse, a 630mA 250v glass fuse.

The fuse had blown so I bought three today and replaced it. I turned on the light switch at the wall and nothing. I checked the fuse and the new one had blown immediately, I tried again (knowing what would happen) and sure enough the other new ones blew immediately as well.

Could anyone shed any light on what might be the issue here? They have been working fine for years.
 
Sponsored Links
It is possible that someone in the house has replaced one of the bulbs, though they are all away at the moment. I have just removed all of the three bulbs (Tesco Value 12v 50w - whoever it was is a cheapskate!!).

The filaments on them all seem to be alright.
 
Allowing for power supply losses, 650mA is not enough for that much lighting, so coupled with starting surges it's not very surprising that the fuse should blow.

Are you sure that it's supposed to be 50W lamps in there, not 35W?
 
Sponsored Links
There are different 'flavours' of 20mm fuses available, including fast blow and time delay variants.

Have a look at the original fuse. Time delay variants are usually marked something like 250V T 630, and fast blowing something like 250V F 630. Some are rated as very slow to blow, IIRC they are marked TT.

At 230 Volts, 630 mA = 144 Watts, so 3 X 50 Watt lamps is OTT without allowing for any losses.

Of course, it may be because the power supply unit has failed....

Is there any rating stamped on the PSU?
 
Try it with just 1 bulb in and see what happens then,
As tickly t says, most I have seen have a T rated fuse on the input.
 

DIYnot Local

Staff member

If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.

Select the supplier or trade you require, enter your location to begin your search.


Are you a trade or supplier? You can create your listing free at DIYnot Local

 
Back
Top