Few more mains sockets?
- Thread starter pe2dave
- Start date
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Hi
Would not want to load all six sockets at the same time as there is just a single 13 amp supply at the other end on 5 metres of cable. Be ok for a bank of LED lights or a one man workshop with all tools plugged in as they can only use one at a time, but imagine the tangle of cables at the end of the day.
Would not want to load all six sockets at the same time as there is just a single 13 amp supply at the other end on 5 metres of cable. Be ok for a bank of LED lights or a one man workshop with all tools plugged in as they can only use one at a time, but imagine the tangle of cables at the end of the day.
pe2dave
Established Member
I did say, 13A feed.
yes but 6 x 13 is too much. I know this item sounds German and the Germans are very good at engineering but even they cannot create energy within an extension lead.
Doesn't matter if you had 50 plugs on a 13A supply as long as the sum total of tools running doesn't exceed 13A
but how many people stop to think about total loads, thats why so many extension leads and extension leads pluged into extension leads have caused fires.
True, but that's why we have fuses. Just because some people do stupid things doesn't mean that the principle isn't sound.
Marineboy
Established Member
Exactly. The fuse protects the cable. Once the load exceeds the capacity of the cable to carry it the fuse blows and ensures the cable does not overheat.
You are both overlooking some fundermentals here including failure modes. A 13 amp fuse allows a continous 13 amps to flow without interuption. The fuse protects the cable under short circuit conditions, a condition that causes sufficient fault current to flow that will melt the fuse but an overload condition may eventually melt the fuse but not always before something else melts. If you look at the BS1362 characteristics for a 13 amp fuse, a 20 amp current will not blow the fuse. This is why residual current protection is so important, it protects people and in motor control systems you must have overload protection.
https://www.pat-testing-training.net/articles/fuse-operation-characteristics.php
https://www.pat-testing-training.net/articles/fuse-operation-characteristics.php
pe2dave
Established Member
I think that's the purpose of trips and fuses?
If people act irresponsibly there is a price to pay.
Not easy to add a label "Not to be used by idiots"
Hi
Thats because we have become politicaly correct and cannot be totally open and honest, if we could then that label " Not to be used by idiots " would be great.
Thats because we have become politicaly correct and cannot be totally open and honest, if we could then that label " Not to be used by idiots " would be great.
Jester129
Established Member
So, in your shop, how many of those sockets would be in use at the same time?
Think about this carefully.......
Think about this carefully.......
HamsterJam
Let’s take it apart to see what’s inside….
Sooooo - when designing a circuit that will be protected by a 13A fuse to BS1362, the designer should consider it might need to carry 20A indefinitely without melting.
Also residual current devices will not protect against an overload. They are designed to detect an imbalance of current between live and neutral indicating there is power flowing out of the circuit to ground somewhere. Typically they will trip when the imbalance exceeds 30mA which is just 0.03A
No, if you are talking about a 13 amp socket then the designer will only have considered the fixed wiring upto that socket which will be on either a 32amp or 20 amp protective device depending on the type of circuit and wire csa used. They have no control over what the end user may use the supply for but with a 13 amp fuse fitted in the plug the cable csa must be capable of taking the prospective short circuit current in order for the fuse to melt. This is another problem in that everyone seems to fit 13 amp fuses in plugs and not always correctly sized for the cable. An example being some IT equipment I inspected some while back, the three core cables were 0.75mm yet fused with 13 amp fuses, should have been 5 amp.
Yes you are correct, RCD's do not protect circuits from overload, there primary function is the safety of people. A 30mA RCD has to disconnect at 30mA within a specified time and at 0 & 180° of phase. We test test them using expensive automated testers during periodic test and inspection routines but many people do not bother using the self test function at regular intervals and therefore they may actually have no protection.
I have had one of these for 20 years without burning down the workshop or blowing the system. The reason I put this down to is not good fortune, but only having two arms! With the best will in the world I cannot use more than two tools at once and in reality I only use one at a time, because one hand is dominant and the other could not drill in a straight line. So yes sometimes I might have a drill, sander and a small router plugged in at once, I only use them one at a time. It hangs above the bench for small power tools.
So as long as you do not plug in the 3kw electric fire, dust extractor and 3hp router you are going to be fine.
So as long as you do not plug in the 3kw electric fire, dust extractor and 3hp router you are going to be fine.
HamsterJam
Let’s take it apart to see what’s inside….
Agreed - however, I was actually referring to the design of the the 6-way extension block which is protected by the fuse in the plug. If a standard UK plug is fitted with a 13A fuse, the designer of the extension should allow for 20A continuous in the extension cable and wiring within the 6-way socket assembly without it melting or catching fire. In addition they should also consider it’s capability to safely carry much higher fault currents, albeit for a limited period of time before the fuse ruptures.
I too have seen appliances fitted with 13A fuses when they should be 5A or even 3A
I worked in a bank headquarters where entire rows of workstations were powered by extension lead plugged into extension lead, I don't know how many... I stopped worrying about extending extension leads then and there.
That said, I got an electrician to install a consumer unit in my workshop with RCD, and properly considered fuses and correctly sized cables, rather than run off extension leads. There's not worrying too much, and then there's due care.
That said, I got an electrician to install a consumer unit in my workshop with RCD, and properly considered fuses and correctly sized cables, rather than run off extension leads. There's not worrying too much, and then there's due care.
My workshop is run using extension leads and in several cases extension leads plugged into more extension leads. The layout has evolved over almost 15 years to be that way as there are limited wall sockets in there.
Does it worry me? No. Has it ever caused a problem or tripped breaker/blown a fuse? No. The most I can use at one time is a light, a dust extractor and a single tool. That never comes to more than 13A. The only time I could go over that is when using the compressor (3kW) but that's on it's own 16amp circuit so I can run that and any other tools at the same time.
Dee J
Established Member
I can see that 6 cables plugged into a hanging socket assembly could get into a tangled mess, but as for overload this unit does have its own thermal overload protection as well as the 13A fuse in the plug.
In my case, I couldn't run my mitre saw with anything else on the same circuit, e.g. the vacuum extractor.
But I'm talking apples and oranges cos I was running an extension cord from a domestic socket.
Now I have power in workshop, I'll be copying Peter Millard's wiring to run the shop Vac, which is essentially a loop of extension cords from the power tool socket on the vac.
But I'm talking apples and oranges cos I was running an extension cord from a domestic socket.
Now I have power in workshop, I'll be copying Peter Millard's wiring to run the shop Vac, which is essentially a loop of extension cords from the power tool socket on the vac.
