EICR, no 3A fuse for a fan

[DPG]

I dont go maintaining/cleaning my fans at night time, so I (radical I know) wander over to the consumer unit and turn off the MCB for the circuit that powers the fan.

Which only isolates the line and not the neutral - apologies for lighting the blue touch paper as it were

 

[Marvo]

.................How is the disconnection level of the fuse, say ~6A = 1.3kW, making a big difference to a fire in such a small area, and are there not thermal cutout to protect the motor, etc........................

Most fractional HP motors like bathroom fans are wound in such a way that the winding impedance is high enough to limit the current to safe levels even if the rotor is locked. They're often marked as 'impedance protected' which means the fault current won't rise high enough to cause a temperature rise that's hazardous or likely to cause a fire. This type of motor design usually won't have a thermal fuse on the windings because the normal running temp is pretty close to the locked rotor temp..

Designing a motor to be impedance protected is good practice and very effective but I'd guess that many nameless far East factories would be churning out motors of sloppy design that wouldn't perform this way in real life so I wouldn't have an issue with a local fuse for added protection. Add to this the fact that most are likely to be ClassII ⧈ with no CPC and therefore no effective RCD protection the hazard becomes increased. I do however wonder where they came up with 3 Amps as an appropriate value for a motor with an RLA/FLA of probably 0.1 - 0.2Amps .... I'd be erring on the side of caution with a 0.5 or 1 Amp fuse if it were my bathroom.

 

[DPG]

Most fractional HP motors like bathroom fans are wound in such a way that the winding impedance is high enough to limit the current to safe levels even if the rotor is locked. They're often marked as 'impedance protected' which means the fault current won't rise high enough to cause a temperature rise that's hazardous or likely to cause a fire. This type of motor design usually won't have a thermal fuse on the windings because the normal running temp is pretty close to the locked rotor temp..

Designing a motor to be impedance protected is good practice and very effective but I'd guess that many nameless far East factories would be churning out motors of sloppy design that wouldn't perform this way in real life so I wouldn't have an issue with a local fuse for added protection. Add to this the fact that most are likely to be ClassII ⧈ with no CPC and therefore no effective RCD protection the hazard becomes increased. I do however wonder where they came up with 3 Amps as an appropriate value for a motor with an RLA/FLA of probably 0.1 - 0.2Amps .... I'd be erring on the side of caution with a 0.5 or 1 Amp fuse if it were my bathroom.

If the fan is connected to an RCD prorected circuit, then the RCD would still detect an unexpected path back to earth in the event of someone receving a shock, even if the fan itself is class II.

 

[Marvo]

Yes, it would give some measure of user protection but probably not in the case of a fire.