One for our resident certified electrical installers ...
I want to add a spur to feed a wall-mounted smart heating controller,
which has a PSU as part of its wall-mount kit. I don't want to have a
fused spur plate on the wall so am planning on putting an in-line
fuseholder in the back-box for the wall-mount kit. I don't have any
concerns about whether this is safe, but I can't decide whether it meets
the regs or needs any specific labelling.
Can anyone here provide the answer?


FYI it's an Evohome system with an ATF600 wall-mount kit.

In article ,
wrote:
One for our resident certified electrical installers ...
I want to add a spur to feed a wall-mounted smart heating controller,
which has a PSU as part of its wall-mount kit. I don't want to have a
fused spur plate on the wall so am planning on putting an in-line
fuseholder in the back-box for the wall-mount kit. I don't have any
concerns about whether this is safe, but I can't decide whether it meets
the regs or needs any specific labelling.
Can anyone here provide the answer?


FYI it's an Evohome system with an ATF600 wall-mount kit.

I'd say anything connected to a ring needs an FCU. Run it from the
lighting circuit?

--
*Being healthy is merely the slowest possible rate at which one can die.

Dave Plowman London SW
To e-mail, change noise into sound.

On 13/12/2020 12:52, Dave Plowman (News) wrote:
In article ,
wrote:
One for our resident certified electrical installers ...
I want to add a spur to feed a wall-mounted smart heating controller,
which has a PSU as part of its wall-mount kit. I don't want to have a
fused spur plate on the wall so am planning on putting an in-line
fuseholder in the back-box for the wall-mount kit. I don't have any
concerns about whether this is safe, but I can't decide whether it meets
the regs or needs any specific labelling.
Can anyone here provide the answer?


FYI it's an Evohome system with an ATF600 wall-mount kit.

I'd say anything connected to a ring needs an FCU. Run it from the
lighting circuit?


You may be correct (I don't know) but the purpose of the fuse is to
protect the (fixed) wiring between the device and the ring so what's the
difference between an in-line fuse inside a back box and a fuse in a
faceplate? I can accept that it would be useful to have a label saying
"fuse inside", but I can't find anything in the regs; hence the question.

The lighting circuits are too far away.

On 13/12/2020 12:37, wrote:
One for our resident certified electrical installers ...
I want to add a spur to feed a wall-mounted smart heating controller,
which has a PSU as part of its wall-mount kit. I don't want to have a
fused spur plate on the wall so am planning on putting an in-line
fuseholder in the back-box for the wall-mount kit. I don't have any
concerns about whether this is safe, but I can't decide whether it meets
the regs or needs any specific labelling.
Can anyone here provide the answer?



I'm not certifiable (yet) but have a couple of questions and comments.

First, what if anything do the manufacturer's instructions require?

Second, I am not clear what - if any - means of local switching and
isolation you end up with. An unswitched FCU to BS 1363-4 counts (Table
537.4 in the regs): you can remove the fuse without risk to life and
limb. But what you propose ain't to BS 1363-4 and AFAICS could only
remove the fuse by opening up the back box. So I think that's a problem.

--
Robin
reply-to address is (intended to be) valid

Has anyone ever opened up a wall wart recently? Time was when there used to
be a fuse or at the very least a temp sensor in the transformer to stop it
all bursting into flames. Most of the little switch mode ones have nothing
at all. I think if anything goes short the main trip on the ring is the
only way to cut the power. They have been known to melt or catch fire.
Surely a little in line wire ended fuse cannot be that expensive to fit
rather than a bit of flexible wire as they use now.
Brian

--

This newsgroup posting comes to you directly from...
The Sofa of Brian Gaff...

Blind user, so no pictures please
Note this Signature is meaningless.!
wrote in message
...
On 13/12/2020 12:52, Dave Plowman (News) wrote:
In article ,
wrote:
One for our resident certified electrical installers ...
I want to add a spur to feed a wall-mounted smart heating controller,
which has a PSU as part of its wall-mount kit. I don't want to have a
fused spur plate on the wall so am planning on putting an in-line
fuseholder in the back-box for the wall-mount kit. I don't have any
concerns about whether this is safe, but I can't decide whether it meets
the regs or needs any specific labelling.
Can anyone here provide the answer?


FYI it's an Evohome system with an ATF600 wall-mount kit.

I'd say anything connected to a ring needs an FCU. Run it from the
lighting circuit?


You may be correct (I don't know) but the purpose of the fuse is to
protect the (fixed) wiring between the device and the ring so what's the
difference between an in-line fuse inside a back box and a fuse in a
faceplate? I can accept that it would be useful to have a label saying
"fuse inside", but I can't find anything in the regs; hence the question.

The lighting circuits are too far away.

On 13/12/2020 15:17, Robin wrote:
On 13/12/2020 12:37, wrote:
One for our resident certified electrical installers ...
I want to add a spur to feed a wall-mounted smart heating controller,
which has a PSU as part of its wall-mount kit. I don't want to have a
fused spur plate on the wall so am planning on putting an in-line
fuseholder in the back-box for the wall-mount kit. I don't have any
concerns about whether this is safe, but I can't decide whether it
meets the regs or needs any specific labelling.
Can anyone here provide the answer?



I'm not certifiable (yet) but have a couple of questions and comments.
Perhaps I'm heading in the "certifiable" direction ;-)

First, what if anything do the manufacturer's instructions require?
There's nothing about protection

Second, I am not clear what - if any - means of local switching and
isolation you end up with.Â* An unswitched FCU to BS 1363-4 counts (Table
Â* 537.4 in the regs): you can remove the fuse without risk to life and
limb.Â* But what you propose ain't to BS 1363-4 and AFAICS could only
remove the fuse by opening up the back box.Â* So I think that's a problem.

You may be right but the fuse would only need replacing if the PSU
fails, and that is in the back box. All connections would be insulated
and I found an inline fuseholder with appropriate protections (although
I can't find it now) so I think it meets the intent, but maybe not the
letter, of the requirements.

Brian Gaff wrote:

Has anyone ever opened up a wall wart recently? Time was when there used to
be a fuse or at the very least a temp sensor in the transformer to stop it
all bursting into flames.

Many of the cheapo PSUs just use a low value resistor as the first
component from the live terminal as a fuse now...

On 14/12/2020 15:22, wrote:
On 13/12/2020 15:17, Robin wrote:
On 13/12/2020 12:37, wrote:
One for our resident certified electrical installers ...
I want to add a spur to feed a wall-mounted smart heating controller,
which has a PSU as part of its wall-mount kit. I don't want to have a
fused spur plate on the wall so am planning on putting an in-line
fuseholder in the back-box for the wall-mount kit. I don't have any
concerns about whether this is safe, but I can't decide whether it
meets the regs or needs any specific labelling.
Can anyone here provide the answer?



I'm not certifiable (yet) but have a couple of questions and comments.
Perhaps I'm heading in the "certifiable" direction ;-)

First, what if anything do the manufacturer's instructions require?
There's nothing about protection

Second, I am not clear what - if any - means of local switching and
isolation you end up with.Â* An unswitched FCU to BS 1363-4 counts
(Table Â*Â* 537.4 in the regs): you can remove the fuse without risk to
life and limb.Â* But what you propose ain't to BS 1363-4 and AFAICS
could only remove the fuse by opening up the back box.Â* So I think
that's a problem.

You may be right but the fuse would only need replacing if the PSU
fails, and that is in the back box. All connections would be insulated
and I found an inline fuseholder with appropriate protections (although
I can't find it now) so I think it meets the intent, but maybe not the
letter, of the requirements.
Following that thought chain, the fuse could be non-replaceable and
considered part of the PSU. So something like
https://www.ebay.co.uk/itm//323268286316 in two layers of heat-shrink.

On 15/12/2020 11:08:09, wrote:
On 14/12/2020 15:22, wrote:
On 13/12/2020 15:17, Robin wrote:
On 13/12/2020 12:37, wrote:
One for our resident certified electrical installers ...
I want to add a spur to feed a wall-mounted smart heating
controller, which has a PSU as part of its wall-mount kit. I don't
want to have a fused spur plate on the wall so am planning on
putting an in-line fuseholder in the back-box for the wall-mount
kit. I don't have any concerns about whether this is safe, but I
can't decide whether it meets the regs or needs any specific labelling.
Can anyone here provide the answer?



I'm not certifiable (yet) but have a couple of questions and comments.
Perhaps I'm heading in the "certifiable" direction ;-)

First, what if anything do the manufacturer's instructions require?
There's nothing about protection

Second, I am not clear what - if any - means of local switching and
isolation you end up with.Â* An unswitched FCU to BS 1363-4 counts
(Table Â*Â* 537.4 in the regs): you can remove the fuse without risk to
life and limb.Â* But what you propose ain't to BS 1363-4 and AFAICS
could only remove the fuse by opening up the back box.Â* So I think
that's a problem.

You may be right but the fuse would only need replacing if the PSU
fails, and that is in the back box. All connections would be insulated
and I found an inline fuseholder with appropriate protections
(although I can't find it now) so I think it meets the intent, but
maybe not the letter, of the requirements.
Following that thought chain, the fuse could be non-replaceable and
considered part of the PSU. So something like
https://www.ebay.co.uk/itm//323268286316 in two layers of heat-shrink.

You ought to be able to isolate the PSU, ideally with a DPST swtich so I
don't see why you are so against a switched FCU.

It doesn't have to be co-located with the PSU as long as it's still
accessible.

On 15/12/2020 11:53, Fredxx wrote:
On 15/12/2020 11:08:09, wrote:
On 14/12/2020 15:22, wrote:
On 13/12/2020 15:17, Robin wrote:
On 13/12/2020 12:37, wrote:
One for our resident certified electrical installers ...
I want to add a spur to feed a wall-mounted smart heating
controller, which has a PSU as part of its wall-mount kit. I don't
want to have a fused spur plate on the wall so am planning on
putting an in-line fuseholder in the back-box for the wall-mount
kit. I don't have any concerns about whether this is safe, but I
can't decide whether it meets the regs or needs any specific
labelling.
Can anyone here provide the answer?



I'm not certifiable (yet) but have a couple of questions and comments.
Perhaps I'm heading in the "certifiable" direction ;-)

First, what if anything do the manufacturer's instructions require?
There's nothing about protection

Second, I am not clear what - if any - means of local switching and
isolation you end up with.Â* An unswitched FCU to BS 1363-4 counts
(Table Â*Â* 537.4 in the regs): you can remove the fuse without risk
to life and limb.Â* But what you propose ain't to BS 1363-4 and
AFAICS could only remove the fuse by opening up the back box.Â* So I
think that's a problem.

You may be right but the fuse would only need replacing if the PSU
fails, and that is in the back box. All connections would be
insulated and I found an inline fuseholder with appropriate
protections (although I can't find it now) so I think it meets the
intent, but maybe not the letter, of the requirements.
Following that thought chain, the fuse could be non-replaceable and
considered part of the PSU. So something like
https://www.ebay.co.uk/itm//323268286316 in two layers of heat-shrink.

You ought to be able to isolate the PSU, ideally with a DPST swtich so I
don't see why you are so against a switched FCU.

It doesn't have to be co-located with the PSU as long as it's still
accessible.
Yes, I was trying to reduce "stuff" on the wall. In fact, because the
controller is wifi-connected, I would probably get better range if the
controller was remote from the PSU and any other metalwork. More thought
required

On 15/12/2020 11:08, wrote:
On 14/12/2020 15:22, wrote:
On 13/12/2020 15:17, Robin wrote:
On 13/12/2020 12:37, wrote:
One for our resident certified electrical installers ...
I want to add a spur to feed a wall-mounted smart heating
controller, which has a PSU as part of its wall-mount kit. I don't
want to have a fused spur plate on the wall so am planning on
putting an in-line fuseholder in the back-box for the wall-mount
kit. I don't have any concerns about whether this is safe, but I
can't decide whether it meets the regs or needs any specific labelling.
Can anyone here provide the answer?



I'm not certifiable (yet) but have a couple of questions and comments.
Perhaps I'm heading in the "certifiable" direction ;-)

First, what if anything do the manufacturer's instructions require?
There's nothing about protection

Second, I am not clear what - if any - means of local switching and
isolation you end up with.Â* An unswitched FCU to BS 1363-4 counts
(Table Â*Â* 537.4 in the regs): you can remove the fuse without risk to
life and limb.Â* But what you propose ain't to BS 1363-4 and AFAICS
could only remove the fuse by opening up the back box.Â* So I think
that's a problem.

You may be right but the fuse would only need replacing if the PSU
fails, and that is in the back box. All connections would be insulated
and I found an inline fuseholder with appropriate protections
(although I can't find it now) so I think it meets the intent, but
maybe not the letter, of the requirements.
Following that thought chain, the fuse could be non-replaceable and
considered part of the PSU. So something like
https://www.ebay.co.uk/itm//323268286316 in two layers of heat-shrink.

If the manufacturer lays down no requirements and your only concern is
to protect the cable (ie no local switching or isolation required) then
ISTM you could just extend the ring final circuit to the PSU and avoid
the need for a fuse altogether. Well, assuming the PSU's connectors can
take 2 x 2.5 mm2 copper

--
Robin
reply-to address is (intended to be) valid

On 15/12/2020 16:30, Robin wrote:
On 15/12/2020 11:08, wrote:
On 14/12/2020 15:22, wrote:
On 13/12/2020 15:17, Robin wrote:
On 13/12/2020 12:37, wrote:
One for our resident certified electrical installers ...
I want to add a spur to feed a wall-mounted smart heating
controller, which has a PSU as part of its wall-mount kit. I don't
want to have a fused spur plate on the wall so am planning on
putting an in-line fuseholder in the back-box for the wall-mount
kit. I don't have any concerns about whether this is safe, but I
can't decide whether it meets the regs or needs any specific
labelling.
Can anyone here provide the answer?



I'm not certifiable (yet) but have a couple of questions and comments.
Perhaps I'm heading in the "certifiable" direction ;-)

First, what if anything do the manufacturer's instructions require?
There's nothing about protection

Second, I am not clear what - if any - means of local switching and
isolation you end up with.Â* An unswitched FCU to BS 1363-4 counts
(Table Â*Â* 537.4 in the regs): you can remove the fuse without risk
to life and limb.Â* But what you propose ain't to BS 1363-4 and
AFAICS could only remove the fuse by opening up the back box.Â* So I
think that's a problem.

You may be right but the fuse would only need replacing if the PSU
fails, and that is in the back box. All connections would be
insulated and I found an inline fuseholder with appropriate
protections (although I can't find it now) so I think it meets the
intent, but maybe not the letter, of the requirements.
Following that thought chain, the fuse could be non-replaceable and
considered part of the PSU. So something like
https://www.ebay.co.uk/itm//323268286316 in two layers of heat-shrink.

If the manufacturer lays down no requirements and your only concern is
to protect the cable (ie no local switching or isolation required) then
ISTM you could just extend the ring final circuit to the PSU and avoid
the need for a fuse altogether.Â* Well, assuming the PSU's connectors can
take 2 x 2.5 mm2 copper

True, although that would be a case of something being "legal" but not
sensible.

In article ,
Robin wrote:
If the manufacturer lays down no requirements and your only concern is
to protect the cable (ie no local switching or isolation required) then
ISTM you could just extend the ring final circuit to the PSU and avoid
the need for a fuse altogether. Well, assuming the PSU's connectors can
take 2 x 2.5 mm2 copper

Can't think of any example of an appliance being wired in directly to a
ring. All go via a plug or FCU. Very different from a radial.

--
*Okay, who stopped the payment on my reality check? *

Dave Plowman London SW
To e-mail, change noise into sound.