As I understand it, in terms of the Sale of Goods Act, I think it already is pretty simple. If a 'retailer' (and I think that includes an electrician who 'supplies and fits' a part) supplies to a customer a part which proves to be 'not of merchantable quality' (aka 'unfit for purpose') (e.g. failed fairly early), then that customer has a right under the SoGA to claim against the retailer (electrician).
Correct.
Furthermore, the Unfair Terms in Consumer Contract Regulations specify a number of things which may not be excluded by contract terms. So taking the example above, if a contract attempted to limit liability for faulty workmanship to 100 days then this would almost certainly be automatically void by law.
However, it's probably not as bad as some people may be thinking. The law says that the supplier is required to do one of three things :
1) effect a repair
2) replace the item
3) provide a refund
A replacement does not have to be identical i the original is no longer available. Anda refund can take account of use the consumer had had - so if something would normally only be expected to last (say) 10 years, and it fails after (say) 3 years, then AIUI it's acceptable to offer a 70% refund.
For the BL car example, if the warranty was provided by BL then it would die with the company. However, the dealer would still be responsible for the statutory rights under SOGA - which would almost certainly be less than that offered by the warranty.
Under SOGA, the "life" isn't specified beyond "reasonable". What is reasonable would have to take into account the nature of the product. For example, if you paid £30 for a high end pan and the handle dropped off after 3 years then that would probably not be reasonable and you'd have a claim; but if you'd paid £1 at the market then you wouldn't really have grounds for complaint ! There is an absolute limit of 6 years based on that being the time you have to bring a civil action under English law.
I do sometimes wonder about those electricians one sees/hears moaning about customers who want to source their own parts ... maybe they are more interested in their customers' interests than their own
I suspect they've never thought about that !