New bathroom extractor fan and light switch

[Echo the husky]

Echo - are you going to take back the fan and complain it got hot?

No, cos I've got the motor on the hob now, and after lighting it a few times, the motor is still working, so the fan is technically not faulty yet! Had to stop as the smell is awful and my cooker hood isn't powerful enough! Motor still runs though!

 

[bernardgreen]

. The insulation on the windings looks good.

The surface of the windings can look perfectly good, the tip layer is in contact with the air and can dissapate heat into the air. The layers deeper into the winding are the ones over heat first. Windings of a burnt out motor can on visual inspection appear undamaged but when the coil is dissected inner layers have been found to have charred / melted insulation and in extreme case signs that the copper had been hot enough to melt.

I would say that, between us, we have gone a long way to confirming how unnecessary/useless would be a 3A fuse.

Then write to the manufacturers, present your evidence, and ask them to justify their instruction to fit a 3 amp fuse.

 

[JohnW2]

The surface of the windings can look perfectly good, the tip layer is in contact with the air and can dissapate heat into the air. The layers deeper into the winding are the ones over heat first.

Maybe, but with a 115° thermal fuse associated with the windings, nothing catastrophic is going to happen.

Then write to the manufacturers, present your evidence, and ask them to justify their instruction to fit a 3 amp fuse.

If it concerns anyone, they could do that. It does not affect me personally, since I use my discretion and 'ignore' any such 'instruction' - something that even BS7671 now allows me to do.

Many people often say that if the product requires protection (over and above that provided by the circuit to which it is connected), that such protection should be provided with the required protection. If there is a (fairly low temp) thermal fuse associated with the motor windings, then I would say that that requirement is satisfied. I think that you would have to scrape the barrel very deeply indeed to come up with a hypothetical scenario in which any significant hazard could arise without the motor windings becoming hot.

Kind Regards, John

 

[Echo the husky]

Well I finally destroyed the motor, sort of. After suspending it over the gas hob with it running, then shutting the flames off once the motor plastic was on fire, the motor finally stopped after the fourth attempt. The plastic kept self extinguishing, the motor finally stopped when one of the strands from the winding opened. No blown 3A fuse or 6A MCB. I did repair the break and the motor is running again!! But I'm done with the smell of burning plastic.

The outer casing and fan blades don't self extinguish though, they burn like hell once ignited.