Something annoyed me this week. That in itself is not unusual: I’m a grumpy, middle-aged man, so annoyance is a regular event, but this annoyed me because it was a myth and oversimplification that I’ve heard repeated as gospel, when it doesn’t atand up to examination.
All bar adapters are rated to 13 amps and that means its all they can safely take. So if you were to plug in a TV, video, lamp and satellite box your pretty safe as that = 12 amps in total.
I’ll just come out and call this. It’s bollocks, even ignoring the poor grammar. Oversimplified, unscientific, made up bullshit. Don’t believe me? Look at this from the Electrical Safety Council. I’ve substituted a DVD player for a VCR, as VCRs are obsolete:
Curiously, they link the ESC calculator from that page. They also, of course, will come and inspect, for a fee…
The site is making a good point: poor electrical safety causes fires, but let’s get a few things straight:
1. Just because something has a 3 amp fuse, it doesn’t mean it draws 3 amps. The 3A fuse is generally there to protect against a dead short in the cable, should it be damaged. In fact, at 240V RMS, the lamp in the example, even if it has a now obsolete 100W GLS bulb, will draw in the region of 0.63A. Here’s a clue: the maximum load of a 13A socket in the UK is over 3000 watts, and most appliances will tell you their ratng in watts. The first examples given on that page will typically only draw a few hundred watts all together, so there is no way on earth you’ll overload a 13A socket with them.
If there were any truth in what the site was telling us, then commercial PDU strips like this one would not be allowed- it has 10 BS1363 outlets, and has a normal Bs1363 plug with a 13A fuse at the other end.
2. Multi-way adaptors are fused with a BS1362 fuse (max 13A) if they have more than 2 outlets. This is so that you cannot create a “tree” of unfused adaptors to connect many appliances to an outlet with no fuse.
3. The wiring system in a UK house is designed such that any considerable overload will blow a fuse or trip a breaker: the wiring regulations specify that the sizes of cable and the connectors should withstand an overload up to a point where a fuse or breaker will trip.
More generally, the ESC have general advice on adaptors and extensions here. Personally I’ve seen scorched, overheated multi-way sockets, but this is usually due to poor manufacture or damage, rather than simple overloading.
It is true that a fuse will not blow at a moderate, sustained overload- so the advice from the ESC should be followed: they know what they’re on about, unlike the website linked at the top of this post.