Hi, all.

At my sister-in-law's for the weekend, and we have a small electrical
problem.

In the utility room, there is a fused switch spur unit above the
worktop,
feeding a socket in a cupboard below. This fused spur unit is
directly on
the ring. The washing machine sits next to the cupboard, and it's
flex
comes into the cupboard via a hole in the side of the carcase. So
far, so
good.

Now, the house owner has replaced the socket with a double socket, and
is
attempting to run a tumble drier off it also.

Needless to say, the 13A fuse in the switch fuse spur unit blows
whenever
both appliances run together.
The drier has a rating plate of 2700W, I can't see the rating on the W/
M,
but the element will be well up there I'd imagine.

The best solution would be to add another fused spur beside the
existing
one, also on the ring, and have it feed the second appliance via its
own
socket.

However, that would be very difficult to do due to how the wires have
been
installed behind the plasterboard and then tiled over.

A possible bodge comes to mind:

How about replacing the fused spur unit with a 13A single socked,
making the
double socket in the cupboard a regular unfused spur?

There are some issues with this. For a start, we loose the appliance
isolating switch above the worktop. I understand this is not
actually a
requirement. Even if it were, the socket is accessible in the
cupboard
without needing to move the appliance, so that may fulfill this
requirement
if it existed. Secondly, I'm going to be drawing somewhat over 13A
off
this spur on the occasion both appliances run together. I'm a
little
unsure about how kosher that is.

Advice?

--
Ron Lowe

On 17 Feb 2007 08:32:53 -0800, mused:

A possible bodge comes to mind:

I like the sound of that!

How about replacing the fused spur unit with a 13A single socked,
making the
double socket in the cupboard a regular unfused spur?

Doesn't sound too much of a bodge actually.

There are some issues with this. For a start, we loose the appliance
isolating switch above the worktop. I understand this is not
actually a
requirement. Even if it were, the socket is accessible in the
cupboard
without needing to move the appliance, so that may fulfill this
requirement
if it existed. '

It doesn't exist, but if you can get to the socket without removing
the appliance then that would be fine. I fit the switched spurs for
convenience so as long as the appliance can be conveniently isolated
then that's all there is to it really.

Secondly, I'm going to be drawing somewhat over 13A
off
this spur on the occasion both appliances run together. I'm a
little
unsure about how kosher that is.

I'd be a bit more concerned if the spur were from the other side of
the house with the cable wrapped in insulation in the roof void but as
it's probably maximum 1m and the cable is rated for 27A then it should
be fine for the infrequent times that the element in the washing
machine is on during a cycle and the tumble dryer is also on.
--
Regards,
Stuart.

On 17 Feb 2007 08:32:53 -0800 someone who may be
wrote this:-

In the utility room, there is a fused switch spur unit above the
worktop, feeding a socket in a cupboard below.

What size is the cable between the switched fused spur and the
socket?


--
David Hansen, Edinburgh
I will *always* explain revoked encryption keys, unless RIP prevents me
http://www.opsi.gov.uk/acts/acts2000/00023--e.htm#54

On Sat, 17 Feb 2007 20:51:51 +0000 someone who may be Owain
wrote this:-

You are allowed to do this, as the assumption is that a doubel socket
will not draw more than 20A (less than 2x13A) and 20A is the normal
rating of 2.5mm T&E.

Under what conditions is 20A the normal rating?


--
David Hansen, Edinburgh
I will *always* explain revoked encryption keys, unless RIP prevents me
http://www.opsi.gov.uk/acts/acts2000/00023--e.htm#54

On 17 Feb, 19:26, David Hansen
wrote:
On 17 Feb 2007 08:32:53 -0800 someone who may be
wrote this:-

In the utility room, there is a fused switch spur unit above the
worktop, feeding a socket in a cupboard below.

What size is the cable between the switched fused spur and the
socket?

--
David Hansen, Edinburgh
I will *always* explain revoked encryption keys, unless RIP prevents me
http://www.opsi.gov.uk/acts/acts2000/00023--e.htm#54

2.5 T+E, approx 1M long, in void space between plasterboard and
blockwork wall ( dot-and-daub construction. )

--
Ron

On 18 Feb 2007 01:14:06 -0800 someone who may be
wrote this:-

On 17 Feb, 19:26, David Hansen
wrote:
On 17 Feb 2007 08:32:53 -0800 someone who may be
wrote this:-

In the utility room, there is a fused switch spur unit above the
worktop, feeding a socket in a cupboard below.

What size is the cable between the switched fused spur and the
socket?

2.5 T+E, approx 1M long, in void space between plasterboard and
blockwork wall ( dot-and-daub construction. )

Then I'm surprised someone fitted a fuse where it joins the ring
main. The reason for fitting a fuse at such a point is to make it a
fused spur and thus allow smaller cable to be used. I would be on
the lookout for a bodge.

However, the cable installation method is somewhere between clipped
direct and in free air, depending on the space between the blockwork
and plasterboard. Assuming the area is not subject to high ambient
temperatures this size of cable is rated at 27 or 30A under those
conditions. Thus fitting a single socket at high level and making
the spur unfused should be fine no matter how the machines are used.

Note this assumes the protective devices are not rewirable fuses and
any advice is worth what you paid for it.

If the house is in England or Wales beware of Mr Prescott.




--
David Hansen, Edinburgh
I will *always* explain revoked encryption keys, unless RIP prevents me
http://www.opsi.gov.uk/acts/acts2000/00023--e.htm#54

David Hansen wrote:

rating of 2.5mm T&E.

Under what conditions is 20A the normal rating?

Installation method 6 (enclosed in conduit in an insulated wall). See
Table 4D5A of BS 7671. The clipped direct rating is 27 A.

--
Andy

On Sun, 18 Feb 2007 10:48:08 +0000 someone who may be Andy Wade
wrote this:-

rating of 2.5mm T&E.

Under what conditions is 20A the normal rating?

Installation method 6 (enclosed in conduit in an insulated wall). See
Table 4D5A of BS 7671. The clipped direct rating is 27 A.

So, not the situation here.


--
David Hansen, Edinburgh
I will *always* explain revoked encryption keys, unless RIP prevents me
http://www.opsi.gov.uk/acts/acts2000/00023--e.htm#54

David Hansen wrote:

So, not the situation here.

True, it's actually method 16 in a duct with a large perimeter, so you
use reference method 3 and Table 4D2A and come up with a rating of 23 A.

This is all a bit irrelevant though. In this situation I'd consider
simply changing the switched fused spur unit for a 20 A DP switch,
leaving the double socket on a short unfused spur. The design rating
is now limited to 20 A by the switch. For the two appliances mentioned
it's unlikely that the load will exceed 20 A for long periods. (I'm
assuming normal domestic use and that it's not a commercial laundry!)

I'd be more concerned about reviewing the loading and load distribution
on the ring itself in regard to reg. 433-02-04, rather than this little
spur alone.

BTW that switched fused spur unit should have been a simple switch in
the first place. Overload protection is provided by the appliance plug
fuse and there's no point at all in a second fuse.

--
Andy

On Sun, 18 Feb 2007 12:15:33 +0000 someone who may be Andy Wade
wrote this:-

True, it's actually method 16 in a duct with a large perimeter,

Debatable. Given the relatively large volume of air compared to a
duct, the fact that the cable is vertical and can lose heat on both
surfaces and the fact that this air can then circulate vertically
(and thus lose rather more heat than it could do in a horizontal
duct) I would say that the cable can be rated higher than 23A.


--
David Hansen, Edinburgh
I will *always* explain revoked encryption keys, unless RIP prevents me
http://www.opsi.gov.uk/acts/acts2000/00023--e.htm#54

On Sun, 18 Feb 2007 12:15:33 +0000, Andy Wade
mused:

David Hansen wrote:

BTW that switched fused spur unit should have been a simple switch in
the first place. Overload protection is provided by the appliance plug
fuse and there's no point at all in a second fuse.

Either\or really.
--
Regards,
Stuart.

On Sun, 18 Feb 2007 09:57:54 +0000, David Hansen
mused:

Then I'm surprised someone fitted a fuse where it joins the ring
main. The reason for fitting a fuse at such a point is to make it a
fused spur and thus allow smaller cable to be used. I would be on
the lookout for a bodge.

The switched fused spur is fitted for convenience. Many many thousands
of under counter sockets are fitted like this up and down the country
and have been for many years.

I can assume then that you are in no way an electrician of any kind or
have any electrical experience?
--
Regards,
Stuart.

On Sun, 18 Feb 2007 13:53:32 +0000 someone who may be Lurch
wrote this:-

The switched fused spur is fitted for convenience.

A 20A DP switch is just as convenient.



--
David Hansen, Edinburgh
I will *always* explain revoked encryption keys, unless RIP prevents me
http://www.opsi.gov.uk/acts/acts2000/00023--e.htm#54

On Sun, 18 Feb 2007 16:41:39 +0000, David Hansen
mused:

On Sun, 18 Feb 2007 13:53:32 +0000 someone who may be Lurch
wrote this:-

The switched fused spur is fitted for convenience.

A 20A DP switch is just as convenient.

But is very much more less common than a switch fuse. Both methods do
the same job, isolate a single socket below a worktop.

Some installations will have flex outlets rather than single sockets
to allow appliances to g back and extra 20-30mm so you would have to
have a fused spur in this instance. If a fused spur is installed at
the outset then the transition from socket to otlet is easierif
required at a later date.
--
Regards,
Stuart.

"Owain" wrote in message
...
wrote:
Now, the house owner has replaced the socket with a double socket, and
is attempting to run a tumble drier off it also.
Needless to say, the 13A fuse in the switch fuse spur unit blows
whenever both appliances run together.
A possible bodge comes to mind:
How about replacing the fused spur unit with a 13A single socked,
making the double socket in the cupboard a regular unfused spur?

You are allowed to do this, as the assumption is that a doubel socket will
not draw more than 20A (less than 2x13A) and 20A is the normal rating of
2.5mm T&E.

The rating plate on the W/M is 2100w @240, and the dryer is 2700W @240.
This computes to 20A, so right on the limit.


However if you believe that 20A would not be sufficient for both
appliances simultaneously, you should not install an unfused spur to
supply them.

Could you put a single socket direct on the ring, and a *single* socket as
an unfused spur?

Yes, I could, but then I'd need to drill a hole in the worktop to pass the
appliance flex up to one socket. ( And chop the moulded plug to pass the
flex thru the hole, then fit a new plug. ) And I'm here for a social visit,
not a DIY fest.

If the cable from spur to ring is less than 2.5mm you won't be able to
remove the fusing anyway.

Not a problem, it's 2.5 T+E.

Owain

I just did it.
As bodges go, it's reading fairly low on the bodge-o-meter.
He still had the old single socket lying around which he'd replaced with the
double, so I just used it to replace the fused switched spur as per my plan.
Avoided a trip to a shed to buy anything, and we got on with out social
nicieties.

And now 7 hours later, I'm back home.

As regards Part Pee, whistles tunelessly.
They were planning to run the drier off an extension cord from the kitchen.

--
Ron