Hi all,

What are the current 'rules' on those multiway trailing sockets as
would be found round the back of most PC's (+ printer, scanner, cable
modem / router) these days please?

I think I remeber something about there an indicator light light
showing they are on and possibly being fused (assuming the one in the
plug top covers it?) but do they also need a switch ..?

Would it make any difference if they were to be used in an office /
shop environment ( assuming they are allowed in the first place if so
how please)?

All the best ..

T i m

"T i m" wrote:
Hi all,

What are the current 'rules' on those multiway trailing sockets as
would be found round the back of most PC's (+ printer, scanner, cable
modem / router) these days please?

I think I remeber something about there an indicator light light
showing they are on and possibly being fused (assuming the one in the
plug top covers it?) but do they also need a switch ..?

Would it make any difference if they were to be used in an office /
shop environment ( assuming they are allowed in the first place if so
how please)?

All the best ..

T i m

Trailing sockets on sale in the UK meet electrical safety standards.

At work, for added safety, it could be argued that they should be used in
conjunction with a residual current device, but there are no regulations
about this. They should be included in PAT testing and trailing leads on the
floor should be made safe with a rubber cable cover.

Phil

On Tue, 25 Apr 2006 21:13:11 +0100, "Phil Anthropist"
wrote:

"T i m" wrote:
Hi all,

What are the current 'rules' on those multiway trailing sockets as
would be found round the back of most PC's (+ printer, scanner, cable
modem / router) these days please?

I think I remeber something about there an indicator light light
showing they are on and possibly being fused (assuming the one in the
plug top covers it?) but do they also need a switch ..?

Would it make any difference if they were to be used in an office /
shop environment ( assuming they are allowed in the first place if so
how please)?

All the best ..

T i m

Trailing sockets on sale in the UK meet electrical safety standards.

At work, for added safety, it could be argued that they should be used in
conjunction with a residual current device, but there are no regulations
about this. They should be included in PAT testing and trailing leads on the
floor should be made safe with a rubber cable cover.

Phil

Cheers Phil .. seems straightforward enough then?

All the best ..

T i m

In article ,
T i m writes:
Hi all,

What are the current 'rules' on those multiway trailing sockets as
would be found round the back of most PC's (+ printer, scanner, cable
modem / router) these days please?

I think I remeber something about there an indicator light light
showing they are on and possibly being fused (assuming the one in the
plug top covers it?) but do they also need a switch ..?

I doubt any of these are required. The danger with indicator
lamps is that someone might believe one. Obviously, the socket
block and cable need appropriate fuse protection, but that
would normally be covered by the plug top fuse.

Would it make any difference if they were to be used in an office /
shop environment ( assuming they are allowed in the first place if so
how please)?

I would suggest you make up some rules for yourself for extension cords
(regardless of number of socket outlets they have)...
Never daisy-chain.
Never use them as a substitute for getting the required number
of fixed sockets installed in the right places.
Always route the cable where it can't get damaged.
Always use high quality ones, not bargin basement ones.
Leads up to 12m long must be 1.25mm² conductors.
Leads up to 15m long must be 1.5mm² conductors.
Leads up to 25m long must be 2.5mm² conductors (which won't fit
into a standard 13A plug).
Don't use high current appliances like kettles and heaters with them.
Don't forget to get them inspected and PAT tested regularly.
Don't forget to get the installation inspected and tested regularly,
and review the loading on circuits which might never have been
designed to handle the number of appliances now commonly used.

--
Andrew Gabriel

Andrew Gabriel wrote:

I would suggest you make up some rules for yourself for extension cords

Never use them as a substitute for getting the required number
of fixed sockets installed in the right places.
Always use high quality ones, not bargin basement ones.
Leads up to 12m long must be 1.25mm² conductors.
Leads up to 15m long must be 1.5mm² conductors.
Leads up to 25m long must be 2.5mm² conductors (which won't fit
into a standard 13A plug).
Don't use high current appliances like kettles and heaters with them.
Don't forget to get the installation inspected and tested regularly,

in each of the above cases, why?

NT

On 25 Apr 2006 20:52:17 GMT, (Andrew
Gabriel) wrote:


What are the current 'rules' on those multiway trailing sockets as
would be found round the back of most PC's (+ printer, scanner, cable
modem / router) these days please?

I think I remeber something about there an indicator light light
showing they are on and possibly being fused (assuming the one in the
plug top covers it?) but do they also need a switch ..?

I doubt any of these are required. The danger with indicator
lamps is that someone might believe one. Obviously, the socket
block and cable need appropriate fuse protection, but that
would normally be covered by the plug top fuse.

Would it make any difference if they were to be used in an office /
shop environment ( assuming they are allowed in the first place if so
how please)?

I would suggest you make up some rules for yourself for extension cords
(regardless of number of socket outlets they have)...

Ok ..

Never daisy-chain.

I wouldn't, unless it was a temp extension lead with say an inspection
lamp on the end.

Never use them as a substitute for getting the required number
of fixed sockets installed in the right places.

Again, 'yes' for 'real' load devices (kettles, fires etc) or where
you know how many devices there will be (fridge freezer) but how many
double sockets would most of us actually fit behind our HiFi / TV
areas (I've just counted 10!) ;-)

Always route the cable where it can't get damaged.

Makes sense ..

Always use high quality ones, not bargin basement ones.

Again, if you wanted to extend a socket away from behind the bed and
use it for a mobile phone and iPod chargers I don't think *any*
'certified' jobby would be a problem (even if only £1.99 from a shed)
would it? The 'problems' come (as normal) from people not knowing how
to use stuff (be it electrical sockets, cars, drills etc). Like the
lad that used my (still partly coiled) 'heavy duty' extension lead for
a wallpaper steamer. What do their parents teach them about .. that
was explained to my daughter the first time we used a 'wound' cable ..
?

Leads up to 12m long must be 1.25mm² conductors.
Leads up to 15m long must be 1.5mm² conductors.
Leads up to 25m long must be 2.5mm² conductors (which won't fit
into a standard 13A plug).

Ok, handy info ta ;-)

Don't use high current appliances like kettles and heaters with them.

Nope ..

Don't forget to get them inspected and PAT tested regularly.

Sounds like a good idea but I've never seen a PAT tester in the flesh
(or anyone testing stuff with them but I'm sure they must do
somewhere?)

Don't forget to get the installation inspected and tested regularly,

Apart from big, formal companies who actually has this done (I guess
everyone should but to they)? The number of places I visited as a
Comms engineer where I would see the mains cable sheath pulled out of
the clamp on 13A plug top and trailing sockets etc ;-(

And I wonder how many houses have the appropriate fuse in every plug?

and review the loading on circuits which might never have been
designed to handle the number of appliances now commonly used.

True, but again in the real world I wonder how often this happens? I
am aware of the implications when I put most stuff together because I
have been working in electronics / electrical for 30 odd years. I
doubt the average man-in-the-street would consider the implications of
plugging in a toaster or bedside lamp?

Good general advice though Andrew .. thanks ;-)

All the best ..

T i m

wrote in message
ups.com...
Andrew Gabriel wrote:
Leads up to 12m long must be 1.25mm² conductors.
Leads up to 15m long must be 1.5mm² conductors.
Leads up to 25m long must be 2.5mm² conductors (which won't fit
into a standard 13A plug).

in each of the above cases, why?

To ensure that the overall loop resistance is low enough for the fuse to
blow quickly in the event of a fault.

--
M Stewart
Milton Keynes, UK
http://www.megalith.freeserve.co.uk/oddimage.htm



*** Posted via a free Usenet account from http://www.teranews.com ***

Malcolm Stewart wrote:
wrote in message
ups.com...
Andrew Gabriel wrote:

Leads up to 12m long must be 1.25mm² conductors.
Leads up to 15m long must be 1.5mm² conductors.
Leads up to 25m long must be 2.5mm² conductors (which won't fit
into a standard 13A plug).

in each of the above cases, why?

To ensure that the overall loop resistance is low enough for the fuse to
blow quickly in the event of a fault.

From CRC Handbook of Chemistry and Physics, 77th edition, 1996-1997,
2.588 mm^2 copper wire is 0.00319 ohms per metre. 25m x 2 x 0.00319 =
0.152 ohms. So theres no way that 25m of 2.5mm^2 would have any
noticeable effect on fuse or mcb action, ditto for 25m of 1.5mm^2.

0.152 ohm drops 1.99v at 13A, so v drop is still ok with wire half that
size.


NT

In article . com,
writes:
From CRC Handbook of Chemistry and Physics, 77th edition, 1996-1997,
2.588 mm^2 copper wire is 0.00319 ohms per metre. 25m x 2 x 0.00319 =
0.152 ohms. So theres no way that 25m of 2.5mm^2 would have any
noticeable effect on fuse or mcb action, ditto for 25m of 1.5mm^2.

Your figures are miles off those in the wiring regs (Table 4H3B):
0.019 ohms per metre for 2.5mm² @ 60C
0.032 ohms per metre for 1.5mm² @ 60C
0.037 ohms per metre for 1.25mm² @ 60C

25m x 2 x 0.019 = 0.95 ohms.
Max Zs for 13A BS1362 fuse is 2.53 ohms for 0.4 seconds disconnect
(Table 41B1), so that extension cord alone is using up 38% of the
allowable Zs. (Strictly, Table 41B1 only applies to fixed wiring,
but the principle is the same regardless.)

Also, checking Table 41C, max allowable CPC impedance with a 13A
BS1362 fuse is 0.75 ohms. 25m of 1.5mm² would be 0.8 ohm alone,
without adding on the resistance of the other parts of the CPC.
(Again, Table 41C only applies to fixed wiring, but the principle
is the same.)

0.152 ohm drops 1.99v at 13A, so v drop is still ok with wire half that
size.

25m x 2 x 0.019 x 13 = 12.35V drop.
This could be on top of max allowed drop in the wiring installation.

--
Andrew Gabriel

In article . com,
writes:
Andrew Gabriel wrote:
I would suggest you make up some rules for yourself for extension cords
Never use them as a substitute for getting the required number
of fixed sockets installed in the right places.

Permanent wiring is much safer than temporary wiring used permanently.

Always use high quality ones, not bargin basement ones.

Some cheap ones don't have good quality sockets. Extremely few have
sockets which are anywhere near the quality of even the worse fixed
socket outlets.

Leads up to 12m long must be 1.25mm² conductors.
Leads up to 15m long must be 1.5mm² conductors.
Leads up to 25m long must be 2.5mm² conductors (which won't fit
into a standard 13A plug).

Already discussed (earth fault loop impedance, which should
result in PAT test failure). Also, if you don't have any
rated less than 13A, then it's impossible to overload them
even when people don't stick to no-kettle rules and the like.

Don't use high current appliances like kettles and heaters with them.

Kettles and heaters and other high current appliances should
be properly provisioned for, which would include providing
proper socket outlets.

Don't forget to get the installation inspected and tested regularly,

There's no point PAT testing all your appliances and extension
cords if half your socket outlets have no earth connected.

Oh, and I missed one:

Don't coil or bunch up excessive cord length, as it can overheat;
use extension cords of the right length, and in temporary
situations, always fully uncoil cords and lay them out so the
heat can dissipate.

--
Andrew Gabriel

On 26 Apr 2006 08:32:20 GMT, Andrew Gabriel wrote:

In article . com,
writes:
From CRC Handbook of Chemistry and Physics, 77th edition, 1996-1997,
2.588 mm^2 copper wire is 0.00319 ohms per metre. 25m x 2 x 0.00319 =
0.152 ohms. So theres no way that 25m of 2.5mm^2 would have any
noticeable effect on fuse or mcb action, ditto for 25m of 1.5mm^2.

Your figures are miles off those in the wiring regs (Table 4H3B):
0.019 ohms per metre for 2.5mm² @ 60C
0.032 ohms per metre for 1.5mm² @ 60C
0.037 ohms per metre for 1.25mm² @ 60C

25m x 2 x 0.019 = 0.95 ohms.
Max Zs for 13A BS1362 fuse is 2.53 ohms for 0.4 seconds disconnect
(Table 41B1), so that extension cord alone is using up 38% of the
allowable Zs. (Strictly, Table 41B1 only applies to fixed wiring,
but the principle is the same regardless.)

Also, checking Table 41C, max allowable CPC impedance with a 13A
BS1362 fuse is 0.75 ohms. 25m of 1.5mm² would be 0.8 ohm alone,
without adding on the resistance of the other parts of the CPC.
(Again, Table 41C only applies to fixed wiring, but the principle
is the same.)

0.152 ohm drops 1.99v at 13A, so v drop is still ok with wire half that
size.

25m x 2 x 0.019 x 13 = 12.35V drop.
This could be on top of max allowed drop in the wiring installation.

Oh, I do so enjoy it when someone quotes *reliable* facts.

--
the dot wanderer at tesco dot net

Andrew Gabriel wrote:
In article . com,
writes:

Your figures are miles off those in the wiring regs (Table 4H3B):

Oops. Thanks!

NT

T i m wrote:
On 25 Apr 2006 20:52:17 GMT, (Andrew
Gabriel) wrote:
Don't forget to get them inspected and PAT tested regularly.

Sounds like a good idea but I've never seen a PAT tester in the flesh
(or anyone testing stuff with them but I'm sure they must do
somewhere?)

Well, they are a standard piece of electrical test equipment. They
aren't all suitable for testing everything, and some of them can do
testing much faster than others.

However, the inspection part of "Inspection and Testing" is very
much more important than the testing part. The inspection is the
part which finds the majority of faults, as most are down to visible
physical defects, and you pick these up with no more than a
screwdriver. A PAT tester can't see the cable is pulled out of the
cord grip, or a hot air paint stripper is being used as a hairdrier,
both of which are failures. So even if you don't have a PAT tester,
you can still get most of the benefits just by doing the inspection.

Don't forget to get the installation inspected and tested regularly,

Apart from big, formal companies who actually has this done (I guess
everyone should but to they)? The number of places I visited as a

I was really answering for a workplace where you've got employers
liability related to a number of Acts and insurance, and often frequent
changes in use of work areas. There isn't anywhere near as much
justification for doing this in the home, nor can a periodic inspection
and test be performed on domestic wiring as effectively as it can in
commercial premises.

Comms engineer where I would see the mains cable sheath pulled out of
the clamp on 13A plug top and trailing sockets etc ;-(

You should draw this to their attention.

And I wonder how many houses have the appropriate fuse in every plug?

Except for extension cords and old appliances which predate current
EU regs, you can use a 13A fuse in every plug. In much of the rest
of Europe, appliances are protected at 16A, and they have to be
designed to work across the whole EU market nowadays.
I'm not suggesting that you go and refit all your plugtop fuses at 13A,
but it's not really a problem if they already are.

and review the loading on circuits which might never have been
designed to handle the number of appliances now commonly used.

True, but again in the real world I wonder how often this happens? I

Larger companies take this more seriously, particularly US ones
in my experience (it's a much more serious issue with US wiring,
and they tend to presume the rest of the world has the same
poor wiring that they do).

--
Andrew

On 26 Apr 2006 04:52:03 -0700, wrote:


snip considered reply

Thanks Andrew.

T i m

We were somewhere around Barstow, on the edge of the desert, when the
drugs began to take hold. I remember (Andrew
Gabriel) saying something like:

Leads up to 25m long must be 2.5mm² conductors (which won't fit
into a standard 13A plug).

Course it does.
--

Dave