Fans and Fuses
- Thread starter Adrian80
- Start date
Fans with timer overrun and the like are designed to have their supply fused at 5 or 6 Amps. The problem can come with 10A lighting circuits, in which case further information should be sought from the manufacturer.
A standard triple pole fan isolator is what you need.
A standard triple pole fan isolator is what you need.
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In general a 6A B rated MCB will trip before a 3A BS1362 fuse will blow and the fuse in a portable appliance is selected purely to protect the cable and the smallest cable permitted can be protected with a 3A fuse so there are now two standard sizes of fuse 3A and 13A so most appliances will have one or the other.
There are 1, 2, 5, 7, and 10A fuses but these are non preferred sizes so will not normally be stipulated for use in a plug or FCU.
In the main with lighting because of the use of ceiling roses which are only rated at 5/6 amp it will be fused at 5/6 amp. When the junction box or the switch rather than the ceiling rose is used to distribute the power it is possible that the system is rated at over 5/6A and one could use a MCB of up to 16A but in the main systems with more than a 6A MCB are breaking the rules by allowing more than 5/6 amp to pass through the ceiling rose.
Most BA22d lamp holders are rated 3A and bulbs should have built in fuses but technically connecting the plug in florescent units should only be permitted when they have 3A fuses inside.
The fans however don't connect through the BA22d lamp holder so there is no reason for a 3A fuse. The use of a 3A fuse will not protect the fan if it was to stall it would still draw less than 3A so it will not save the fan the fuse is there to protect the cable.
If the fan is powered from the 32A ring main then the 3A fuse in the FUC will be required.
I one wanted one could use a 2 pole light switch and fuse to 3A but personally I don't think this is necessary.
To be pedantic if the manufacture states 3A than 3A should be used and if a pedantic inspector wanted to fail it because it only had a 5/6A over current device one could not prove he was wrong. But I would hope inspectors would not be that pedantic.
There are 1, 2, 5, 7, and 10A fuses but these are non preferred sizes so will not normally be stipulated for use in a plug or FCU.
In the main with lighting because of the use of ceiling roses which are only rated at 5/6 amp it will be fused at 5/6 amp. When the junction box or the switch rather than the ceiling rose is used to distribute the power it is possible that the system is rated at over 5/6A and one could use a MCB of up to 16A but in the main systems with more than a 6A MCB are breaking the rules by allowing more than 5/6 amp to pass through the ceiling rose.
Most BA22d lamp holders are rated 3A and bulbs should have built in fuses but technically connecting the plug in florescent units should only be permitted when they have 3A fuses inside.
The fans however don't connect through the BA22d lamp holder so there is no reason for a 3A fuse. The use of a 3A fuse will not protect the fan if it was to stall it would still draw less than 3A so it will not save the fan the fuse is there to protect the cable.
If the fan is powered from the 32A ring main then the 3A fuse in the FUC will be required.
I one wanted one could use a 2 pole light switch and fuse to 3A but personally I don't think this is necessary.
To be pedantic if the manufacture states 3A than 3A should be used and if a pedantic inspector wanted to fail it because it only had a 5/6A over current device one could not prove he was wrong. But I would hope inspectors would not be that pedantic.
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