FCU on bathroom lighting

[stl]

Hi,

I have just moved into a new property built 1993 with a wylex cartridge fuse cu and out of pure curiosity i have a number of queries?

The main bathroom has a FCU (5A) outside it which controls the light in the bathroom and fan. All are on the upstairs lighting cicuit from the CU. The separate en-suite also has a 5A FCU outside it which controls the fan and light in it. The first FCU also controls the lights / fan in the en-suite and main bedroom light?

Any reason why the installation would be designed like this?. There seems to be no 3pole isolation of the fan(s).

Also, the main CU has one of the fuses replaced with a B16 MCB for the newly installed combi boiler, which is itself off a 3AM FCU next to the boiler. Is this ok, why would a B16 MCB be used?

Are the cartridge fuses ok? - up to 17th edition requirements?. Is it worth updating to MCB's and is this notifable?. Most of the circuits are RCD protected except lighting and upstairs towel rail in the airing cupboard which is labelled as a heater on the CU.

Any thoughts or comments welcomes?

Thanks

 

[holmslaw]

..

 

[ericmark]

Many fans are rated 3A and the lighting supply is normally 5/6A and this is one way to comply with manufactures recommendation.

I don't think it is really required but can't see a good reason to change it. Many fans are just fitted to satisfy building inspector and never used again. There are many that don't strictly comply with Part F and often they are switched with lights even where there is light from outside. The only thing I would really worry about with fans is if there are any gas fires without a balanced flue one must ensure you can't get a negative pressure in the house which will cause flue gases to be drawn into the house. This includes tumble driers and kitchen fans. Where air is blown out it must be replaced from some where and we don't want the some where to be gas fire flue. As long as that is OK then no worries.