Fitting Isolator or Henley block

[plugwash]

OK more like bomb disposal than welding in reverse.

Is it safe to change MCBs with the consumer unit isolated by the 100A switch

depends on the CU, if its well wired and in good condition then its perfectly safe, if shrouds are missing or the tails are badly terminated then it can be somewhat more dangerous. Always take great care not to touch anything the first time you take the lid off a CU and then have a good look at the area on the supply side of the switch to see if there is any exposed live metal.

 

[john 45]

Why reduce 32A to 20A?

- surely its ultimately safer if you dont need the watts to protect against short circuits and cable over heating

 

[davy_owen_88]

surely its ultimately safer if you dont need the watts to protect against short circuits and cable over heating

The difference in disconnection times in the event of a short circuit between a 20A and 32A MCB is negligible and there shouldn't be any problems with cables overheating as long as the cables were suitably sized in the first place.

I want to reduce the old MCBs from 32A to 20A - Garage Shed, security lights, and remove a 5 amp bell MCB - not used and replace with cover.

Are you saying your security lights are on a dedicated 32A circuit or that your security lights are run off the 32A shed circuit?

Depending on your answers I really don't think there is any need for you to mess with the consumer unit. Assuming everything is working (and to a safe standard) and you don't need the space taken up by the bell transformer just leave it alone. You just run the risk of making a problem.

Davy

 

[ricicle]

If you must do it then have some one observing you who is practised in post electrocution first aid and CPR.

Paul Daniels??