# Few more mains sockets?



## pe2dave (18 Dec 2020)

Amazon have a 'drop down' 6 outlet mains lead. Lots of sockets, 13A feed.


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## Spectric (18 Dec 2020)

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.


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## pe2dave (18 Dec 2020)

I did say, 13A feed.


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## Spectric (18 Dec 2020)

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.


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## Rorschach (18 Dec 2020)

Spectric said:


> 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


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## Spectric (18 Dec 2020)

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.


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## Rorschach (18 Dec 2020)

Spectric said:


> 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.


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## Marineboy (18 Dec 2020)

Rorschach said:


> True, but that's why we have fuses. Just because some people do stupid things doesn't mean that the principle isn't sound.


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.


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## Spectric (18 Dec 2020)

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.





__





Why does a 13A fuse not blow at 13A?


The rated current is the current that it can pass without not overheating the plug. A 13A fuse will allow a current of 20A to pass without blowing.




www.pat-testing-training.net


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## pe2dave (19 Dec 2020)

Spectric said:


> 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.



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"


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## Spectric (19 Dec 2020)

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.


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## Jester129 (19 Dec 2020)

So, in your shop, how many of those sockets would be in use at the same time?
Think about this carefully.......


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## HamsterJam (19 Dec 2020)

Spectric said:


> 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.
> 
> 
> 
> ...



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


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## Spectric (20 Dec 2020)

HamsterJam said:


> 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.


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.


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## PAC1 (20 Dec 2020)

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.


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## HamsterJam (20 Dec 2020)

Spectric said:


> 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.



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


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## jcassidy (21 Dec 2020)

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.


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## Rorschach (21 Dec 2020)

jcassidy said:


> 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.



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.


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## Dee J (21 Dec 2020)

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.


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## jcassidy (21 Dec 2020)

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.


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## Jacob (21 Dec 2020)

I ran a fixed loop circuit around my workshop with 8 double sockets on it, on a board about 40" from the floor. The clever detail (well I think it is) is that there's a little 4" wide continuous shelf on the top edge of the board which is useful as a shelf, but also protects the sockets from damage if things are dropped in their vicinity or leant against the wall etc.


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## Spectric (21 Dec 2020)

Hi

If you need extension leads then you have a lack of sockets. I can understand running an extension lead outside to power a lawn mower or to vacuum a car but within a workshop they should not be needed because it is easier and tidier to just have plenty of sockets. They are also a tripping hazzard and how many of us have been caught out by a cable.


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## PAC1 (21 Dec 2020)

Hence a cube you can suspend from a rafter or the ceiling.
My bench is in the middle of the workshop so it was either dig the floor up and install some floor boxes (not ideal in a workshop), ditto but fix the outlets to the bench (not ideal as I need to move my bench) or suspend from the ceiling on a chain to use with no trip hazard (I just headbut it instead). Not really much of a choice.


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## Sandyn (21 Dec 2020)

I have a few of my fixed power tools/extraction/floodlights run off one 13A socket which has a couple of further extensions. , but no serious power on them. It means I just have one switch at night to shut down everything. No trip hazard, because I run the extensions over-head on other furniture. I have plenty of sockets on the wall, but was fed up with cables running to the tools. That was more of a trip hazard for me. I'm in the process of mounting fixed sockets on the ceiling to tidy things up a bit. I will probably add a relay with NVR configuration so I can isolate everything on the radial circuit.


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## Sideways (21 Dec 2020)

A alternative to consider :
Install a captive cable outlet in your fixed wiring - the type used for connecting electric radiators etc with a switch and a 13A fuse built in.
Fit a decent quality and size of flex into it - such as H07RNF rubber - and run to a blue CE (commando) industrial socket.
Hang the socket from the ceiling on a chain (several types have a moulded eye built into the case that can be used for this)
Commando sockets are strong and durable for workshop duty with good cable clamps and seals.
A single socket is not so big to have hanging from above.
Making the connection via a 13A fused switched outlet is a safe connection to your domestic spur or ring main. It provides the fuse protection that isn't built into the commando plug/ socket.
Chain support ensures that you don't pull on the flex.
If you want a full 16A from the commando socket, you will need to get a protected 16A circuit installed, but I use this for selected power or portable tools that would otherwise be on a 13A plug.
My machines are on their own individual circuits.
It's not a business premises or shared space where someone might plug a true 16A load into my 13A fused commando sockets without realising the limitation.


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## Sandyn (22 Dec 2020)

Sideways said:


> Install a captive cable outlet in your fixed wiring - the type used for connecting electric radiators etc with a switch and a 13A fuse built in.
> Fit a decent quality and size of flex into it - such as H07RNF rubber


Thanks! That's a good idea. I only have one machine that needs a 16A supply, but that's in another workshop just now. Makes the connection more accessible,


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## pe2dave (22 Dec 2020)

Spectric said:


> Hi
> 
> If you need extension leads then you have a lack of sockets. I can understand running an extension lead outside to power a lawn mower or to vacuum a car but within a workshop they should not be needed because it is easier and tidier to just have plenty of sockets. They are also a tripping hazzard and how many of us have been caught out by a cable.


And in the middle of the workshop? That's my reason for the extension, hung from the rafters. No trip hazard, just convenience.


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## TRITON (22 Dec 2020)

I know your pain. Used to have extension plugged into extension, then back and forth unplugging this to plug in that.
Until I had a sparks in to fit a bathroom heater, and while youre at it.... fit me 4 double sockets in the workshop...

I now have projects on the go...and get this .... free sockets


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## flying haggis (22 Dec 2020)

if this 6way socket with its 13a fuse bothers people so much why not put a smaller fuse in the plug supplying the cube. ok you wont be able to use high powered tools but you will have piece of mind that it cant run at 20a as has been suggested as possible. or just not buy it! i have some of these style of 4 way blocks that i would hang from the ceiling. they have 4 holes for permanent mounting, the two near the switch, yes a switch as well as a fuse in the block itself, will take a 4mm bolt to fix the chain(s) to so that the cable is to the top








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## flying haggis (22 Dec 2020)

TRITON said:


> I know your pain. Used to have extension plugged into extension, then back and forth unplugging this to plug in that.
> Until I had a sparks in to fit a bathroom heater, and while youre at it.... fit me 4 double sockets in the workshop...
> 
> I now have projects on the go...and get this .... free sockets


dont fret about it, you will soon fill them


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## Sideways (22 Dec 2020)

When an electrician installs fixed wiring, they select cables based on the fuse or circuit breaker that is protecting the circuit. This makes allowances for "small overloads of long duration". These are 40 odd % in the case of circuit breakers and (if I remember) about 73% for circuits protected by fuses which take longer to blow. As long as the wiring was properly designed and installed, you have no need to worry about 20 A flowing through a 13A fuse for as long as it takes to blow.
If you have installed your own wiring and have never hear of this before, you were meddling with something that you weren't competent to do 

The thing pe2dave linked to is a German brand - probably designed with a bunch of 16A schuko sockets and tweaked for the UK market with our 13A outlets.


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