bathroom extractor with pir sensor

[stillp]

The fact (which I would hope that a court would accept) is that a 3A fuse would only ever blow after, and as a result of a catastrophic failure in the fan - so they really could not rationally argue that the failure was in any way caused by the absence of the fuse.

I suspect that they're not worried about any possibility that a failure of their fan was due to the lack of a 3A fuse, but they're worried that if the fan develops a catastrophic short-circuit such that the supply cables overheat and cause a fire, they might be held liable. Fitting a 3A fuse limits the fault current that could be caused by a failure of the fan to less than the withstand of any cable likely to be used.

 

[ekmdgrf]

It is unnecessary, at least as far as the wiring is concerned. However, as we've discussed many times, some manufacturers probably have these 'requirements' for external fusing as a consequence of not having included adequate internal protection in their products.

There's a saying in the electronics world: "The component is there to protect the fuse".

 

[JohnW2]

I suspect that they're not worried about any possibility that a failure of their fan was due to the lack of a 3A fuse, but they're worried that if the fan develops a catastrophic short-circuit such that the supply cables overheat and cause a fire, they might be held liable. Fitting a 3A fuse limits the fault current that could be caused by a failure of the fan to less than the withstand of any cable likely to be used.

That may be how they think, but I would have thought that it's probably an unnecessary concern. If such a situation arose, they could surely argue that the householder's fixed wiring should be adequately protected against anything up to and including a dead short in whatever it's connected to, and therefore that if any harm comes to the householder's wiring (including any consequential fires etc.) they could not be held liable?

They might (IMO) at least indicate that an additional (3A) fuse is not required if (as it the most common situation) the circuit powering the fan is protected by a 5A or 6A OPD. Indeed, I would suspect that in the case of a "catastrophic short circuit" in the fan, in many cases a B6 MCB would probably operate before a 3A fuse, anyway!

Kind Regards, John

 

[stillp]

You're assuming the MIs are written with the intent of being helpful and technically correct. Unfortunately in many companies instructions are written by someone whose job is to defend against any possible civil action involving their company.

 

[JohnW2]

You're assuming the MIs are written with the intent of being helpful and technically correct. Unfortunately in many companies instructions are written by someone whose job is to defend against any possible civil action involving their company.

I don't doubt that is true. However, as you will realise, I was not commenting on this unhelpful and over-cautious approach in general but, rather, specifically about their statement that the product's warranty would be invalidated by the absence of a 3A fuse. I still find it hard to believe that a court (if it ever got to one) would support that position - since, for reasons I explained above, I just cannot see how absence of the fuse could result in anything happening that would/could be subject to a 'product warranty' claim! As I said, by the time the fuse blew, the product would already have 'failed'!

Kind Regards, John

 

[stillp]

A court wouldn't support them, but the manufacturer could tell the customer that the MIs were not followed so the warranty is invalid, which might be seen as likely to frighten off many potential claimants.
Some decades ago I was involved with selling a new product into the USA. The instructions prepared in the USA included a half-page on what the product could be used for, and the rest of the 12 page booklet consisted of warnings about incorrect use. When I questioned this my attention was drawn to a law suit in the USA in which $1.5 million had been awarded to someone who'd been cutting his hedge with a rotary lawnmower. When the mower fell off the hedge he'd tried to catch it, losing several fingers in the process. The court awarded damages on the grounds that no warning had been given about such misuse.
Sadly that sort of thinking has now become established on this side of the Atlantic.

 

[JohnW2]

A court wouldn't support them, but the manufacturer could tell the customer that the MIs were not followed so the warranty is invalid, which might be seen as likely to frighten off many potential claimants.

That was my very point - that one should not be intimidated by these threats that a warranty would be invalidated for unreasonable reasons - since, if one ever had to take it to law (or threaten that), one would probably win. Whether such 'intimidation' should be allowed is another matter!

...in the USA ... When the mower fell off the hedge he'd tried to catch it, losing several fingers in the process. The court awarded [$1.5 million] damages on the grounds that no warning had been given about such misuse. Sadly that sort of thinking has now become established on this side of the Atlantic.

Yep. That's the same reason why you'd be hard pressed to find any 'package insert' for a medicine in the US which did not include "death" as one of the possible 'side-effects', no matter how innocuous the medicine concerned. Although we are, unfortunately, moving in that direction on this side of the water, we fortunately are still a bit more sensible than our overseas cousins!

Kind Regards, John