3 ms·

but ganging up unfused plugs like that spells 'fire' Nah, it'll be fine. Actually this sort of thinking is probably because of the "dangerous plugs" pictures w

by ErrantX 16y ago

but ganging up unfused plugs like that spells 'fire' Nah, it'll be fine. Actually this sort of thinking is probably because of the "dangerous plugs" pictures we are always shown as children. A stuffed up socket just looks automatically dangerous to us. I guess you're coming from the perspective of overloading the socket. This is surprisingly hard to do - but you can do it equally well across multiple sockets (basically, if your fuse breaker is going to let it burn it doesn't care much where the devices are plugged in :)) so it is something of a misconception to consider a crowded socket particularly dangerous. People happily use an 8 gang extension cable without batting an eyelid. More importantly having fuses in the plugs is unlikely to help all that much, the crucial fuse is the one in your circuit breaker. The current will divide across the sockets (my circuit theory is rusty so I won't try any figures :)) and it is the socket taking the brunt. While you would likely eventually see a spike that trips one of the plugs I'm betting the socket catching fire is more likely. And, finally, I suspect these would be rated (well, if they weren't vapour-ware) for devices with internal fusing or low power draws. I'd also suspect that the plug "holder" would be fused. BTW it is somewhat moot anyway because I believe those red tabs are a fuse holder :)

jacquesm 16y ago
The big difference between a single 8 gang extension and this system is that you're putting all those connections in series, whereas in an 8 gang extension they're in parallel. That's a lot of contact resistance, this socket already has twice as much contact resistance as a normal one (because of the twist in the contact section). If we're talking 'light' consumers, say below a 100W or so you might get away with it but if a 'heavy' consumer would be plugged in as the last element in a series of 'light' ones you'd be concentrating an awful lot of energy in to a small spot. But hey, what do I know about electricity ;) At 10 mOhm (new and very clean) per contact with 5 plugs 'ganged' up that's 5x4x10mOhm or .2 Ohm. With a 240V working voltage and a 2 KW consumer that would be 8.3 Amps so about 1.6 V drop, 8.3x1.6=13 Watts, which the copper wiring alone can probably remove without any heat building up. If the contacts wear and get older they could get to as much as .3 Ohm apiece. Now you're looking at 5x4x.3 Ohm, 6 Ohm, in total so that's a 49 V drop, almost 400 Watts to dissipate just in the contacts. That's a lot of heat. That's why some older wall sockets will get warm (or even hot) when you plug in a large consumer. And your circuit protection will not care even a little bit about all this, it's just another heater.
- ErrantX 16y ago
  Hmm you sure they are pulling in series? Depends on the design on the plug but I imagine it works the same way as any other multi-socket (pulling it in parallel), why would they set it up to work in series (that would be a big design flaw). One imagines that once this made it to the engineering level (this is just design, right) this would be sorted out. If we're talking 'light' consumers, say below a 100W or so you might get away with it but if a 'heavy' consumer would be plugged in as the last element in a series of 'light' ones you'd be concentrating an awful lot of energy in to a small spot. Think about what is likely to have these sorts of plugs; Laptops, for example, usually pull under 2A. Which means you could have 10 plugged in before it starts to be a problem, and even pulling 20A to your socket (which is a common rating for mains sockets) still leaves plenty of leeway. I'm not sure what my iPhone or radio alarm clock is rated for (am at work atm) but I can't imagine they add up to more than 1A draw. As I mentioned, the problem on mains networks overloading comes, usually, from a faulty trip switch. If it is doing its job the most that you can do is trip it (and maybe fry some equipment that isn't earthed/fused properly). Stocking up a plug is pretty safe; again, as mentioned, it is easy (and more common) to overload the whole circuit via a number of plugs :) EDIT: meh, it's impossible, anyway, for it to be set up in series, otherwise you wouldn't be able to pull power correctly. with 5 plugs 'ganged' up Uh, there are three plugs in the design? But this is a reasonable concern (the heat issue). In practice it is not too much of a worry, if a device is demanding 2KW this plug is clearly unsuitable (for a number of reasons).
  - jacquesm 16y ago
    > Hmm you sure they are pulling in series? The contacts are in series: live->socket1->socket2->socket3->socket4->socket5->load | | neut<-socket1<-socket2<-socket3<-socket4<-socket5<-load So the current for the last load passes through all the intermediary sockets. It does not pass through their wiring but it does pass from pin-to-pin. It would have to and no engineering trick will get you around that when you're piggybacking stuff. > Think about what is likely to have these sorts of plugs; Laptops, for example, usually pull under 2A. Which means you could have 10 plugged in before it starts to be a problem, and even pulling 20A to your socket (which is a common rating for mains sockets) still leaves plenty of leeway. Until someone plugs their hairdryer or fryer in to the last one, which is possible because it is still valid socket.

by ErrantX 16y ago

jacquesm 16y ago

The big difference between a single 8 gang extension and this system is that you're putting all those connections in series, whereas in an 8 gang extension they're in parallel. That's a lot of contact resistance, this socket already has twice as much contact resistance as a normal one (because of the twist in the contact section). If we're talking 'light' consumers, say below a 100W or so you might get away with it but if a 'heavy' consumer would be plugged in as the last element in a series of 'light' ones you'd be concentrating an awful lot of energy in to a small spot. But hey, what do I know about electricity ;) At 10 mOhm (new and very clean) per contact with 5 plugs 'ganged' up that's 5x4x10mOhm or .2 Ohm. With a 240V working voltage and a 2 KW consumer that would be 8.3 Amps so about 1.6 V drop, 8.3x1.6=13 Watts, which the copper wiring alone can probably remove without any heat building up. If the contacts wear and get older they could get to as much as .3 Ohm apiece. Now you're looking at 5x4x.3 Ohm, 6 Ohm, in total so that's a 49 V drop, almost 400 Watts to dissipate just in the contacts. That's a lot of heat. That's why some older wall sockets will get warm (or even hot) when you plug in a large consumer. And your circuit protection will not care even a little bit about all this, it's just another heater.

ErrantX 16y ago
Hmm you sure they are pulling in series? Depends on the design on the plug but I imagine it works the same way as any other multi-socket (pulling it in parallel), why would they set it up to work in series (that would be a big design flaw). One imagines that once this made it to the engineering level (this is just design, right) this would be sorted out. If we're talking 'light' consumers, say below a 100W or so you might get away with it but if a 'heavy' consumer would be plugged in as the last element in a series of 'light' ones you'd be concentrating an awful lot of energy in to a small spot. Think about what is likely to have these sorts of plugs; Laptops, for example, usually pull under 2A. Which means you could have 10 plugged in before it starts to be a problem, and even pulling 20A to your socket (which is a common rating for mains sockets) still leaves plenty of leeway. I'm not sure what my iPhone or radio alarm clock is rated for (am at work atm) but I can't imagine they add up to more than 1A draw. As I mentioned, the problem on mains networks overloading comes, usually, from a faulty trip switch. If it is doing its job the most that you can do is trip it (and maybe fry some equipment that isn't earthed/fused properly). Stocking up a plug is pretty safe; again, as mentioned, it is easy (and more common) to overload the whole circuit via a number of plugs :) EDIT: meh, it's impossible, anyway, for it to be set up in series, otherwise you wouldn't be able to pull power correctly. with 5 plugs 'ganged' up Uh, there are three plugs in the design? But this is a reasonable concern (the heat issue). In practice it is not too much of a worry, if a device is demanding 2KW this plug is clearly unsuitable (for a number of reasons).
- jacquesm 16y ago
  > Hmm you sure they are pulling in series? The contacts are in series: live->socket1->socket2->socket3->socket4->socket5->load | | neut<-socket1<-socket2<-socket3<-socket4<-socket5<-load So the current for the last load passes through all the intermediary sockets. It does not pass through their wiring but it does pass from pin-to-pin. It would have to and no engineering trick will get you around that when you're piggybacking stuff. > Think about what is likely to have these sorts of plugs; Laptops, for example, usually pull under 2A. Which means you could have 10 plugged in before it starts to be a problem, and even pulling 20A to your socket (which is a common rating for mains sockets) still leaves plenty of leeway. Until someone plugs their hairdryer or fryer in to the last one, which is possible because it is still valid socket.