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Old Nov 03, 2007, 01:55 PM
Registered User
Surrey Hills
Joined Aug 2004
54 Posts
Wiring the Workshop....Garage!

My inquiry is:- Should I use top sockets like MK for around 12 a shot or cheapies at 3.50 a shot? Metal clad of course.
BTW, I don't wish to get into the 'should I do it myself bit/part P argument' 'cos I AM doing it myself.
Opinions much appreciated.
Roy
elj221c is offline Find More Posts by elj221c
Old Nov 03, 2007, 03:05 PM
Brad.
Guest
n/a Posts
Re: Wiring the Workshop....Garage!


"elj221c" <elj221c.2zhjkn@rcgroups.com> wrote in message
news:elj221c.2zhjkn@rcgroups.com...
>
> My inquiry is:- Should I use top sockets like MK for around 12 a shot
> or cheapies at 3.50 a shot? Metal clad of course.
> BTW, I don't wish to get into the 'should I do it myself bit/part P
> argument' 'cos I AM doing it myself.
> Opinions much appreciated.
> Roy
>
>
> --
> elj221c
> ------------------------------------------------------------------------
> elj221c's Profile: http://www.rcgroups.com/forums/member.php?u=37570
> View this thread: http://www.rcgroups.com/forums/showthread.php?t=766734
>



Nothing wrong with the "cheapie" sockets as such, I did mine with 8 double
metal clad sockets and plastic conduit all around the garage/workshop and
have not had any problems at all. Try Screwfix as they usually have good
deals on for multiple amounts ;
http://www.screwfix.com/cats/A331911...tal-Clad-Range
Cheers.
Brad.


Old Nov 03, 2007, 04:53 PM
Peter Fairbrother
Guest
n/a Posts
Re: Wiring the Workshop....Garage!

elj221c wrote:
> I don't wish to get into the 'should I do it myself bit/part P
> argument' 'cos I AM doing it myself.



Yeaaay!
Old Nov 03, 2007, 05:29 PM
Guy Fawkes
Guest
n/a Posts
Re: Wiring the Workshop....Garage!


elj221c wrote:
> My inquiry is:- Should I use top sockets like MK for around =A312 a shot
> or cheapies at =A33.50 a shot? Metal clad of course.
> BTW, I don't wish to get into the 'should I do it myself bit/part P
> argument' 'cos I AM doing it myself.
> Opinions much appreciated.
> Roy
>
>


I currently work for an electrical distributor, you would not believe
the mark up on this stuff...

I'm talking 1000% or more

get yourself down to your local industrial estate in the am and follow
the sparky vans to find your local distro

forget all ideas about "top" brands, that went years ago, the majority
of it is imported, eg only one place in the uk now actually makes
electrical cable...

metal clad sockets need a good earthing, cheapo plastic socket faces
like contactum on appleby dry lining boxes is good enough, don;t
scrimp on the cable gauge, make sure you install a loop and not spurs,
and use a discrete breaker box with fuse and rcd trips for safety, so
10mm flat twin and earth from the house, and 2.5mm 3 core loop for the
socket ring.

a box of ten fused rubber top lyvia 13a plugs is about 2.50 trade.....

HTH etc

Old Nov 04, 2007, 01:25 AM
Electricky Dicky
Guest
n/a Posts
Re: Wiring the Workshop....Garage!

On Sat, 03 Nov 2007 14:29:44 -0700, Guy Fawkes
<davenull@blueyonder.co.uk> wrote:

>
>elj221c wrote:
>> My inquiry is:- Should I use top sockets like MK for around 12 a shot
>> or cheapies at 3.50 a shot? Metal clad of course.
>> BTW, I don't wish to get into the 'should I do it myself bit/part P
>> argument' 'cos I AM doing it myself.
>> Opinions much appreciated.
>> Roy
>>
>>

>
>I currently work for an electrical distributor, you would not believe
>the mark up on this stuff...
>
>I'm talking 1000% or more
>
>get yourself down to your local industrial estate in the am and follow
>the sparky vans to find your local distro
>
>forget all ideas about "top" brands, that went years ago, the majority
>of it is imported, eg only one place in the uk now actually makes
>electrical cable...
>
>metal clad sockets need a good earthing, cheapo plastic socket faces
>like contactum on appleby dry lining boxes is good enough,


The above statement tends to indicate that plastic boxes do not need
the same level of earthing as metal. If that is what is meant then
"cobblers"! The earthing is there for the item that is plugged in, not
just for the socket.

In a workshop environment metal sockets are preferred. A long piece of
bar falling against one will not cause the same level of problems. Dry
lining boxes are for "Dry lined walls", the fact that the OP discussed
metal sockets indicates that he is considering surface mounting,
therefore "Dry lining boxes" do not come into the picture.

If you are using surface mount metal boxes then "Egatube" or similar
is the correct way to go. A ring main in 2.5mm2 singles. Carry the
earth around looping into each faceplate with a 1.5mm2 single wire
back the the earth point in the box.

Snip

--
Richard

Nb "None" if the survey goes through ok
Old Nov 04, 2007, 03:50 AM
Austin Shackles
Guest
n/a Posts
Re: Wiring the Workshop....Garage!

On or around Sat, 3 Nov 2007 12:55:59 -0500, elj221c
<elj221c.2zhjkn@rcgroups.com> enlightened us thusly:

>
>My inquiry is:- Should I use top sockets like MK for around 12 a shot
>or cheapies at 3.50 a shot? Metal clad of course.
>BTW, I don't wish to get into the 'should I do it myself bit/part P
>argument' 'cos I AM doing it myself.
>Opinions much appreciated.
>Roy


The only thing I've noticed about really cheap ones is that sometimes the
contacts within are poorly made, resulting in a poor contact onto the plug
and generating heat. This obviously depends what you plug into it - light
loads will never be a problem, 3HP motors might.
--
Austin Shackles. www.ddol-las.net my opinions are just that
Travel The Galaxy! Meet Fascinating Life Forms...
------------------------------------------------\
>> http://www.schlockmercenary.com/ << \ ...and Kill them.

a webcartoon by Howard Tayler; I like it, maybe you will too!
Old Nov 04, 2007, 05:08 AM
Mark Rand
Guest
n/a Posts
Re: Wiring the Workshop....Garage!

On Sun, 04 Nov 2007 08:50:38 +0000, Austin Shackles
<austinDITCHTHISFORBETTERRESULTS@ddol-las.net> wrote:

>On or around Sat, 3 Nov 2007 12:55:59 -0500, elj221c
><elj221c.2zhjkn@rcgroups.com> enlightened us thusly:
>
>>
>>My inquiry is:- Should I use top sockets like MK for around 12 a shot
>>or cheapies at 3.50 a shot? Metal clad of course.
>>BTW, I don't wish to get into the 'should I do it myself bit/part P
>>argument' 'cos I AM doing it myself.
>>Opinions much appreciated.
>>Roy

>
>The only thing I've noticed about really cheap ones is that sometimes the
>contacts within are poorly made, resulting in a poor contact onto the plug
>and generating heat. This obviously depends what you plug into it - light
>loads will never be a problem, 3HP motors might.


I must admit that nearly all of mine were MK. But the only reason for that was
that they came with the trunking that I scrounged from work to go with the
other trunking that I got from Ebay. I like the 3 compartment trunking because
it has plenty of room for future growth and also allows me to run the
phone/network/loudspeaker/doorbell cables neatly.


Mark Rand
RTFM
Old Nov 04, 2007, 06:55 AM
Guy Fawkes
Guest
n/a Posts
Re: Wiring the Workshop....Garage!


Electricky Dicky wrote:

> The above statement tends to indicate that plastic boxes do not need
> the same level of earthing as metal. If that is what is meant then
> "cobblers"! The earthing is there for the item that is plugged in, not
> just for the socket.


Nevertheless, a plastic socket fascia and box cannot go live, no
matter what happens.

reaching out to switch on or off an appliance of necessity creates
half the stance required for current to flow along your arms and
across your heart and kill you, for the other half all you need is
your other hand on something metalling with a potential difference,
and 240 VAC @ 50 Hz is not required to kill, 6 to 200 milliamperes is
all it takes.

>
> In a workshop environment metal sockets are preferred. A long piece of
> bar falling against one will not cause the same level of problems. Dry
> lining boxes are for "Dry lined walls", the fact that the OP discussed
> metal sockets indicates that he is considering surface mounting,
> therefore "Dry lining boxes" do not come into the picture.


Rubbish, in a workshop environment correctly sited, angled and
protected lewden style plugs and sockets, armoured cables and so on
are preferred, but this costs money and we are talking about a DIYer
doing a "good enough" job on the cheap, not to code or to spec.

In that scenario, with the DIYer doing a "good enough" job on the
cheap, plastic sockets are favourite, yes they can be broken, so can
the metal ones, so take care, ideally put a shield around each socket
in wood, top and sides, metal bars falling all over the place and
liquid spills are signs of sloppy working practices.

dry lining boxes like appleby come in two flavors, cheap metal
stampings and plastic, dry lining means any internal wall above a damp
proof course, eg not a "wet" wall, like a single wall stone build
structure with no cavity, their purpose is to recess the socket fascia
nearly flush to the wall instead of protruding a couple of inches with
surface mount, a lot of this depends on how you're going to run the
cable, in the wall or externally in conduit, of course the OP is
unlikely to spring for conduit too, so it will be cheapo and "good
enough" thorsden style nail and piece of plastic cable ties.

>
> If you are using surface mount metal boxes then "Egatube" or similar
> is the correct way to go.


won't happen, the tube is cheap enough, pence per metre, but the OP
will prolly end up buying marshall tufflex round tees and elbows etc,
and that's where the money starts to go.....

MT kit has again gone down hill in quality, we had a lot of pcv-u
sterling stuff rejected, they're using a new cheaper grade of plastic
and the rear (wall) side simply ain't flat anymore, but that's another
story.

egatube etc also tricks you into all those extra little purchases,
grommets and the like, that's where the money goes, and you have to be
real careful, that stuff traps water, do it wrong and you can duct
water down into a socket... seen it done....


> A ring main in 2.5mm2 singles.


why use singles instead of twin and earth?

6242Y has the same area, only one mousing / threading job to do per
section, an extra free layer of insulation against electrical and
mechanical issues, and it's cheaper, thanks to quantity of
manufacture.

> Carry the
> earth around looping into each faceplate with a 1.5mm2 single wire
> back the the earth point in the box.


this is one of the *many* reasons old school sparkies and non sparkies
have little time for 16th edition etc, 2.5mm2 has a nominal current
capacity of 20 amperes, so in the UK about 4.8kW, with reasonable
voltage drop, 1.5mm2 has a nominal current capacity of 15 amperes, so
about 1200 watts less, you just put all your cookies in the earth wire
acting as a sensor for the various protection devices MCB/RCD etc in
the consumer unit to trip, and nothing left over for the old style of
actually being able to carry any imaginable current thrown at it,
without fuss.... so in the workshop enviornment this was every watt
the live feed wire could supply, plus unforeseen stuff like the
spindle motor failing and dumping excess phase current down it too

we don't even know if the OP has any potentially lethal kit in his
workshop, like inverters to drive machinery or inside machinery such
as welders, and wiring workshops professionally is a world away from
wiring domestic premises professionally

so lets look again at what I said, bearing in mind we know he ain't a
sparky working to code...

a/ 6242y twin and earth makes it easier to get right and harder to
make mistakes*, plus its cheaper too.

b/ plastic sockets make it easier to get right and harder to make
mistakes*, plus its cheaper too

etc etc

* make mistakes means not just making them, but the after effects of
them

Old Nov 04, 2007, 07:01 AM
Guy Fawkes
Guest
n/a Posts
Re: Wiring the Workshop....Garage!

should of course also have said that if cables are enclosed inside
trunking then current carrying capacity is reduced significantly, no
free air cooling etc....

Old Nov 04, 2007, 08:18 AM
Richard Edwards
Guest
n/a Posts
Re: Wiring the Workshop....Garage!

On Sun, 04 Nov 2007 03:55:22 -0800, Guy Fawkes
<davenull@blueyonder.co.uk> wrote:

>
>Electricky Dicky wrote:
>
>> The above statement tends to indicate that plastic boxes do not need
>> the same level of earthing as metal. If that is what is meant then
>> "cobblers"! The earthing is there for the item that is plugged in, not
>> just for the socket.

>
>Nevertheless, a plastic socket fascia and box cannot go live, no
>matter what happens.
>
>reaching out to switch on or off an appliance of necessity creates
>half the stance required for current to flow along your arms and
>across your heart and kill you, for the other half all you need is
>your other hand on something metalling with a potential difference,
>and 240 VAC @ 50 Hz is not required to kill, 6 to 200 milliamperes is
>all it takes.
>
>>
>> In a workshop environment metal sockets are preferred. A long piece of
>> bar falling against one will not cause the same level of problems. Dry
>> lining boxes are for "Dry lined walls", the fact that the OP discussed
>> metal sockets indicates that he is considering surface mounting,
>> therefore "Dry lining boxes" do not come into the picture.

>
>Rubbish, in a workshop environment correctly sited, angled and
>protected lewden style plugs and sockets, armoured cables and so on
>are preferred, but this costs money and we are talking about a DIYer
>doing a "good enough" job on the cheap, not to code or to spec.
>
>In that scenario, with the DIYer doing a "good enough" job on the
>cheap, plastic sockets are favourite, yes they can be broken, so can
>the metal ones, so take care, ideally put a shield around each socket
>in wood, top and sides, metal bars falling all over the place and
>liquid spills are signs of sloppy working practices.
>
>dry lining boxes like appleby come in two flavors, cheap metal
>stampings and plastic, dry lining means any internal wall above a damp
>proof course, eg not a "wet" wall, like a single wall stone build
>structure with no cavity, their purpose is to recess the socket fascia
>nearly flush to the wall instead of protruding a couple of inches with
>surface mount, a lot of this depends on how you're going to run the
>cable, in the wall or externally in conduit, of course the OP is
>unlikely to spring for conduit too, so it will be cheapo and "good
>enough" thorsden style nail and piece of plastic cable ties.


More "cobblers". A dry lining box is used to fix a socket, switch etc
into a "cavity wall"
>>
>> If you are using surface mount metal boxes then "Egatube" or similar
>> is the correct way to go.

>
>won't happen, the tube is cheap enough, pence per metre, but the OP
>will prolly end up buying marshall tufflex round tees and elbows etc,
>and that's where the money starts to go.....


I think that you are assuming too much about the OP's attitude to this
job.
>
>MT kit has again gone down hill in quality, we had a lot of pcv-u
>sterling stuff rejected, they're using a new cheaper grade of plastic
>and the rear (wall) side simply ain't flat anymore, but that's another
>story.
>
>egatube etc also tricks you into all those extra little purchases,
>grommets and the like, that's where the money goes, and you have to be
>real careful, that stuff traps water, do it wrong and you can duct
>water down into a socket... seen it done....


Again you are assuming the the OP is creating a workshop built in a
swimming pool ;-)
>
>> A ring main in 2.5mm2 singles.

>
>why use singles instead of twin and earth?
>
>6242Y has the same area, only one mousing / threading job to do per
>section, an extra free layer of insulation against electrical and
>mechanical issues, and it's cheaper, thanks to quantity of
>manufacture.


Granted it's cheaper but why use the wrong kit for a job. If the OP
decides to use tube then singles are the best way to do it.

>> Carry the
>> earth around looping into each faceplate with a 1.5mm2 single wire
>> back the the earth point in the box.

>
>this is one of the *many* reasons old school sparkies and non sparkies
>have little time for 16th edition etc, 2.5mm2 has a nominal current
>capacity of 20 amperes, so in the UK about 4.8kW, with reasonable
>voltage drop, 1.5mm2 has a nominal current capacity of 15 amperes, so
>about 1200 watts less, you just put all your cookies in the earth wire
>acting as a sensor for the various protection devices MCB/RCD etc in
>the consumer unit to trip, and nothing left over for the old style of
>actually being able to carry any imaginable current thrown at it,
>without fuss.... so in the workshop enviornment this was every watt
>the live feed wire could supply, plus unforeseen stuff like the
>spindle motor failing and dumping excess phase current down it too


I do not have a clue as to what you are on about!
Re "acting as a sensor for the various protection devices MCB/RCD etc"
Are you suggesting that the earth wire not be connected?
I cannot understand your objection to 1.5mm2 for the earth wire, that
is what is in your 6242Y cable and if I dismember correctly the old
7.029 cable had a reduced area earth well befor the 16th edition.! If
you are unhappy with 1.5mm2 and suggest something larger, then singles
are obviously the only way to go
>
>we don't even know if the OP has any potentially lethal kit in his
>workshop, like inverters to drive machinery


If he has a 240v s/phase in and 415v three phase out invertor then I
am sure you will recommend using 2 runs of 6242y and tying back the
spare conductor. Look at the advantages you will say, two earth wires
to act as a sensor ;-)

>or inside machinery such
>as welders, and wiring workshops professionally is a world away from
>wiring domestic premises professionally
>
>so lets look again at what I said, bearing in mind we know he ain't a
>sparky working to code...
>
>a/ 6242y twin and earth makes it easier to get right and harder to
>make mistakes*, plus its cheaper too.
>
>b/ plastic sockets make it easier to get right and harder to make
>mistakes*, plus its cheaper too
>
>etc etc
>
>* make mistakes means not just making them, but the after effects of
>them


I leave it to the OP to do his own thing.
One last point. If the OP wires in 6242Y it will be Brown/blue (After
Part P.)
If tubed in singles there is no identification as to when installed!


--

Richard
Old Nov 04, 2007, 09:27 AM
Guy Fawkes
Guest
n/a Posts
Re: Wiring the Workshop....Garage!


Richard Edwards wrote:

>
> More "cobblers". A dry lining box is used to fix a socket, switch etc
> into a "cavity wall"


not cobblers, fact.

the "dry" in dry lining refers to an internal wall above a DPC, eg a
dry wall, as opposed to a wet wall.


> Again you are assuming the the OP is creating a workshop built in a
> swimming pool ;-)


don't be ridiculous, leaking roofs on outbuildings and garages are
hardly uncommon, I've seen plenty of these leaks ending up as water
dripping from a pendant light fitting or dripping out of a socket at
the end of some conduit, hell, I've even seen plenty of example of
water wicking down through coax from the external telly aerial....



>
> Granted it's cheaper but why use the wrong kit for a job. If the OP
> decides to use tube then singles are the best way to do it.


it's not wrong, you're making assumptions, and quoting 16th ed, which
isn't applicable to the DIYer, who is going to do a "good enough"
job.....

twin and earth is cheaper than singles, tidier than singles, easier
than singles and has that extra layer or electrical and mechanical
protection than singles, it has everything going for it for the DIYer
and nothing against it, 25 quid for 100 metres roll of 6242y and job's
a good un

***FAR*** more important the OP is encouraged to flash the cash on a
decent consumer unit and **appropriate** MCB/RCDs....

MCB come in three types for any given rated current, lets take a 16A
one.

BMCB 16A will trip quickly at between 3 and 4.5 times rated current
CMCB 16A will trip more slowly at between 5 and 10 times rated current
DMCB 16A will trip more slowly still at between 10 and 20 times rated
current

so, type D for thinks like transformers and welders, type C for
inductive stuff like flourescents, and type B for everything else, CB
= circuit breaker, a resettable fuse if you like, you still should fit
and RCD to each circuit, this ( consumer unit) is where the money
goes, twin and earth cable clipped to the wall with plastic contactum
sockets etc is fine, esp if the money is spent on a decent CU with
appropriate MCB/RCDs, that's where the safety will be made.

Old Nov 04, 2007, 09:45 AM
Austin Shackles
Guest
n/a Posts
Re: Wiring the Workshop....Garage!

On or around Sun, 04 Nov 2007 03:55:22 -0800, Guy Fawkes
<davenull@blueyonder.co.uk> enlightened us thusly:

>reaching out to switch on or off an appliance of necessity creates
>half the stance required for current to flow along your arms and
>across your heart and kill you, for the other half all you need is
>your other hand on something metalling with a potential difference,
>and 240 VAC @ 50 Hz is not required to kill, 6 to 200 milliamperes is
>all it takes.


get yer units straight. you can't mix volts and amps, you know.
--
Austin Shackles. www.ddol-las.net my opinions are just that
Travel The Galaxy! Meet Fascinating Life Forms...
------------------------------------------------\
>> http://www.schlockmercenary.com/ << \ ...and Kill them.

a webcartoon by Howard Tayler; I like it, maybe you will too!
Old Nov 04, 2007, 11:32 AM
Guy Fawkes
Guest
n/a Posts
Re: Wiring the Workshop....Garage!


Austin Shackles wrote:
> On or around Sun, 04 Nov 2007 03:55:22 -0800, Guy Fawkes
> <davenull@blueyonder.co.uk> enlightened us thusly:
>
> >reaching out to switch on or off an appliance of necessity creates
> >half the stance required for current to flow along your arms and
> >across your heart and kill you, for the other half all you need is
> >your other hand on something metalling with a potential difference,
> >and 240 VAC @ 50 Hz is not required to kill, 6 to 200 milliamperes is
> >all it takes.

>
> get yer units straight. you can't mix volts and amps, you know.


my units are right, UK mains is a nominal 240 VAC @ 50 Hz, 6 to 200
milliamperes is all it takes to stop the human heart, at 240 volts
that's 1.44 to 48 watts, at 24 V that's 0.144 to 4.8 watts, a trivial
amount of power, easily obtainable from a capacitor, whether you live
or die depends upon the vagaries of the current path through the human
body, if any and if so what proportion crosses the heart, if it's
between 0.006 and 0.2 amperes you're dead, game over, end of story.

high frequency currents (like a tesla coil) in the kilo and megahertz
range tend to run in the surface of the skin rather than through the
body, very low frequency AC, eg 50/60Hz and DC are essentially the
same, both run through the core of the body, the difference with DC is
you have a 50/50 chance of the muscle spasm locking you onto the
source of shock or making other muscles pull you further into the
machinery, hence the "danger" of DC.

the illegal in the UK high voltage stun zapper things work off an
internal PP9 battery, but use a fairly high frequency, hence pain but
not death, unless you happen to have a pacemaker...

=========================

trivial things like selecting 6242y twin and earth over single gives
you an extra layer of electrical and mechanical insulation, high
voltage guys (tesla coilers etc) work with one hand in their pocket to
prevent making a circuit across the heart, these are trivial things
like correct use of the pusher stick on a circular saw, but they all
increase the odds in your favour as/when/if the random event happens,
by a significant margin, for approaching zero "cost" or effort.

Old Nov 04, 2007, 11:44 AM
Richard Edwards
Guest
n/a Posts
Re: Wiring the Workshop....Garage!

On Sun, 04 Nov 2007 06:27:46 -0800, Guy Fawkes
<davenull@blueyonder.co.uk> wrote:

>
>Richard Edwards wrote:
>
>>
>> More "cobblers". A dry lining box is used to fix a socket, switch etc
>> into a "cavity wall"

>
>not cobblers, fact.
>
>the "dry" in dry lining refers to an internal wall above a DPC, eg a
>dry wall, as opposed to a wet wall.
>

Cobblers
This is a dry lining box
http://www.screwfix.com/app/sfd/cat/...92060&id=44827
This is a box for cutting into a solid wall
http://www.screwfix.com/app/sfd/cat/...92102&id=79195

Both are used in dry applications. Neither are required by the OP as
he is intending fitting Surface mount metalclad sockets.

>> Again you are assuming the the OP is creating a workshop built in a
>> swimming pool ;-)

>
>don't be ridiculous, leaking roofs on outbuildings and garages are
>hardly uncommon, I've seen plenty of these leaks ending up as water
>dripping from a pendant light fitting or dripping out of a socket at
>the end of some conduit, hell, I've even seen plenty of example of
>water wicking down through coax from the external telly aerial....
>

I will grant you all of these, however tube in a workshop is the way
to go.
>
>>
>> Granted it's cheaper but why use the wrong kit for a job. If the OP
>> decides to use tube then singles are the best way to do it.

>
>it's not wrong, you're making assumptions, and quoting 16th ed, which
>isn't applicable to the DIYer, who is going to do a "good enough"
>job.....
>


I have not quoted the 16th edition

>twin and earth is cheaper than singles, tidier than singles, easier
>than singles and has that extra layer or electrical and mechanical
>protection than singles,

How you can suggest that 6242Y has better protection than singles in
tube I know not!

> it has everything going for it for the DIYer
>and nothing against it, 25 quid for 100 metres roll of 6242y and job's
>a good un


Thats a good price
>
>***FAR*** more important the OP is encouraged to flash the cash on a
>decent consumer unit and **appropriate** MCB/RCDs....
>

I see a change of tack here away from some points raised

>MCB come in three types for any given rated current, lets take a 16A
>one.

Better to take a 32A one as we were talking ring main for the sockets.

>BMCB 16A will trip quickly at between 3 and 4.5 times rated current
>CMCB 16A will trip more slowly at between 5 and 10 times rated current
>DMCB 16A will trip more slowly still at between 10 and 20 times rated
>current


All of those breakers have similar tripping times at the suggested
multiples of current. Needs a better description for the layman.

>current
>
>so, type D for thinks like transformers and welders, type C for
>inductive stuff like flourescents, and type B for everything else, CB
>= circuit breaker, a resettable fuse if you like,


>you still should fit and RCD to each circuit,


I look forward to your justification of this statement

--

Richard
Old Nov 04, 2007, 12:36 PM
Austin Shackles
Guest
n/a Posts
Re: Wiring the Workshop....Garage!

On or around Sun, 04 Nov 2007 08:32:16 -0800, Guy Fawkes
<davenull@blueyonder.co.uk> enlightened us thusly:

>
>Austin Shackles wrote:
>> On or around Sun, 04 Nov 2007 03:55:22 -0800, Guy Fawkes
>> <davenull@blueyonder.co.uk> enlightened us thusly:
>>
>> >reaching out to switch on or off an appliance of necessity creates
>> >half the stance required for current to flow along your arms and
>> >across your heart and kill you, for the other half all you need is
>> >your other hand on something metalling with a potential difference,
>> >and 240 VAC @ 50 Hz is not required to kill, 6 to 200 milliamperes is
>> >all it takes.

>>
>> get yer units straight. you can't mix volts and amps, you know.

>
>my units are right, UK mains is a nominal 240 VAC @ 50 Hz, 6 to 200
>milliamperes is all it takes to stop the human heart, at 240 volts
>that's 1.44 to 48 watts, at 24 V that's 0.144 to 4.8 watts, a trivial
>amount of power, easily obtainable from a capacitor, whether you live
>or die depends upon the vagaries of the current path through the human
>body, if any and if so what proportion crosses the heart, if it's
>between 0.006 and 0.2 amperes you're dead, game over, end of story.


not arguing that, but what you said sounded wrong, and I think was. Assuming
correct figures, you can die from as little as 6mA across the heart itself.

The voltage is more or less irrelevant. You can and I have got many KV from
vehicle ignition, but very little current. I've also had 240V mains,
although not up one arm and down the other. Maybe I've been lucky.



>
>high frequency currents (like a tesla coil) in the kilo and megahertz
>range tend to run in the surface of the skin rather than through the
>body, very low frequency AC, eg 50/60Hz and DC are essentially the
>same, both run through the core of the body, the difference with DC is
>you have a 50/50 chance of the muscle spasm locking you onto the
>source of shock or making other muscles pull you further into the
>machinery, hence the "danger" of DC.
>
>the illegal in the UK high voltage stun zapper things work off an
>internal PP9 battery, but use a fairly high frequency, hence pain but
>not death, unless you happen to have a pacemaker...
>
>=========================
>
>trivial things like selecting 6242y twin and earth over single gives
>you an extra layer of electrical and mechanical insulation, high
>voltage guys (tesla coilers etc) work with one hand in their pocket to
>prevent making a circuit across the heart, these are trivial things
>like correct use of the pusher stick on a circular saw, but they all
>increase the odds in your favour as/when/if the random event happens,
>by a significant margin, for approaching zero "cost" or effort.

--
Austin Shackles. www.ddol-las.net my opinions are just that
Travel The Galaxy! Meet Fascinating Life Forms...
------------------------------------------------\
>> http://www.schlockmercenary.com/ << \ ...and Kill them.

a webcartoon by Howard Tayler; I like it, maybe you will too!
 


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