Why does it need upgrading to MCBs ?? I have an old Wylex consumer unit containing wire fuses . All you need do is buy a stand alone RCD install it before the fuse box and hey presto ! your whole installation , no matter how old is protected. I am a retired spark and have lived in my house for 36 yrs and never felt the need to upgrade to MCBs and have never had to change a fuse even once !!so

--
For full context, visit https://www.homeownershub.com/uk-diy/stand-alone-rcd-121076-.htm

On Saturday, 15 October 2022 at 17:15:07 UTC+1, Graham wrote:
> Why does it need upgrading to MCBs ?? I have an old Wylex consumer unit containing wire fuses .
> All you need do is buy a stand alone RCD install it before the fuse box and hey presto ! your whole
> installation , no matter how old is protected. I am a retired spark and have lived in my house for
> 36 yrs and never felt the need to upgrade to MCBs and have never had to change a fuse even once !!

A whole-house standalone RCD will NOT be compliant with 18th Edition regulations.

Assuming the house hasn't burnt down in the last 18 years.

Owain

On 15/10/2022 17:15, Graham wrote:
> Why does it need upgrading to MCBs ??  I have an old Wylex consumer unit
> containing wire fuses . All you need do is buy a stand alone RCD install
> it before the fuse box and hey presto !  your whole installation , no
> matter how old is protected.  I am a retired spark and have lived in my
> house for 36 yrs and never felt the need to upgrade to MCBs and have
> never had to change a fuse even once !!so
>

Fuck me a reply to a 17 year old post and Graham manages to somehow get
everything in his reply incorrect.

Panto season?

--
For full context, visit https://www.homeownershub.com/uk-diy/stand-alone-rcd-121076-.htm

On 15/10/2022 17:15, Graham wrote:

Gosh a 17yo thread has popped back into life from the 16th edition!

> Why does it need upgrading to MCBs ??  I have an old Wylex consumer unit
> containing wire fuses . All you need do is buy a stand alone RCD install
> it before the fuse box and hey presto !  your whole installation

Yes, an installation that was a fairly crap idea during the 15th edition
of BS7671 (which is the last time that practice would have been
considered acceptable). It can potentially results in lots of nuisance
RCD trips, and offers *no* discrimination at all in the even of a earth
leakage fault.

> , no
> matter how old is protected.  I am a retired spark and have lived in my
> house for 36 yrs and never felt the need to upgrade to MCBs and have
> never had to change a fuse even once !!so

Nothing inherently wrong with fuses as such, but "re-wireable" BS3036
fuses have both usability and potential abuse issues. They also impose
limitations on the rest of the installation (such as cable de-rating to
70% of nominal current) due to their higher fusing factor.

--
Cheers,

John.

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In article <tifhfv$2urf4$2@dont-email.me>,
John Rumm <see.my.signature@nowhere.null> wrote:
> On 15/10/2022 17:15, Graham wrote:

> Gosh a 17yo thread has popped back into life from the 16th edition!

> > Why does it need upgrading to MCBs ?? I have an old Wylex consumer unit
> > containing wire fuses . All you need do is buy a stand alone RCD install
> > it before the fuse box and hey presto ! your whole installation

> Yes, an installation that was a fairly crap idea during the 15th edition
> of BS7671 (which is the last time that practice would have been
> considered acceptable). It can potentially results in lots of nuisance
> RCD trips, and offers *no* discrimination at all in the even of a earth
> leakage fault.

> > , no
> > matter how old is protected. I am a retired spark and have lived in my
> > house for 36 yrs and never felt the need to upgrade to MCBs and have
> > never had to change a fuse even once !!so

> Nothing inherently wrong with fuses as such, but "re-wireable" BS3036
> fuses have both usability and potential abuse issues. They also impose
> limitations on the rest of the installation (such as cable de-rating to
> 70% of nominal current) due to their higher fusing factor.

when we moved into this house in 1977, one room had its own CU - Wylex with
wire fuses. I replaced them with MCB, about the same time as I fitted
"whole house" RCD.

> --

--
from KT24 in Surrey, England - sent from my RISC OS 4té
"I'd rather die of exhaustion than die of boredom" Thomas Carlyle

Yes well, I wonder when you reach the point where the complexity of the
protection mechanisms makes the system so unreliable that its pointless
going any further?
Brian

--

--:
This newsgroup posting comes to you directly from...
The Sofa of Brian Gaff...
briang1@blueyonder.co.uk
Blind user, so no pictures please
Note this Signature is meaningless.!
"Owain Lastname" <spuorgelgoog@gowanhill.com> wrote in message
news:23a78fda-ae19-495e-8511-2d1b60aea3b3n@googlegroups.com...
> On Saturday, 15 October 2022 at 17:15:07 UTC+1, Graham wrote:
>> Why does it need upgrading to MCBs ?? I have an old Wylex consumer unit
>> containing wire fuses .
>> All you need do is buy a stand alone RCD install it before the fuse box
>> and hey presto ! your whole
>> installation , no matter how old is protected. I am a retired spark and
>> have lived in my house for
>> 36 yrs and never felt the need to upgrade to MCBs and have never had to
>> change a fuse even once !!
>
> A whole-house standalone RCD will NOT be compliant with 18th Edition
> regulations.
>
> Assuming the house hasn't burnt down in the last 18 years.
>
> Owain
>
>

On Sunday, 16 October 2022 at 00:59:00 UTC+1, John Rumm wrote:
> On 15/10/2022 17:15, Graham wrote:
> Gosh a 17yo thread has popped back into life from the 16th edition!
> > Why does it need upgrading to MCBs ?? I have an old Wylex consumer unit
> > containing wire fuses . All you need do is buy a stand alone RCD install
> > it before the fuse box and hey presto ! your whole installation
> Yes, an installation that was a fairly crap idea during the 15th edition
> of BS7671 (which is the last time that practice would have been
> considered acceptable). It can potentially results in lots of nuisance
> RCD trips, and offers *no* discrimination at all in the even of a earth
> leakage fault.
> > , no
> > matter how old is protected. I am a retired spark and have lived in my
> > house for 36 yrs and never felt the need to upgrade to MCBs and have
> > never had to change a fuse even once !!so
> Nothing inherently wrong with fuses as such, but "re-wireable" BS3036
> fuses have both usability and potential abuse issues.

Breakers are also abusable. Seen people turn one back on time after time after time when there was clearly a problem.

On 17/10/2022 03:11, Animal wrote:
> On Sunday, 16 October 2022 at 00:59:00 UTC+1, John Rumm wrote:
>> On 15/10/2022 17:15, Graham wrote:
>> Gosh a 17yo thread has popped back into life from the 16th edition!
>>> Why does it need upgrading to MCBs ?? I have an old Wylex consumer unit
>>> containing wire fuses . All you need do is buy a stand alone RCD install
>>> it before the fuse box and hey presto ! your whole installation
>> Yes, an installation that was a fairly crap idea during the 15th edition
>> of BS7671 (which is the last time that practice would have been
>> considered acceptable). It can potentially results in lots of nuisance
>> RCD trips, and offers *no* discrimination at all in the even of a earth
>> leakage fault.
>>> , no
>>> matter how old is protected. I am a retired spark and have lived in my
>>> house for 36 yrs and never felt the need to upgrade to MCBs and have
>>> never had to change a fuse even once !!so
>> Nothing inherently wrong with fuses as such, but "re-wireable" BS3036
>> fuses have both usability and potential abuse issues.
>
> Breakers are also abusable. Seen people turn one back on time after time after time when there was clearly a problem.

Indeed - but not quite in the same league as fitting the foil from a
fag box round the fuse, or a nail in the fuse holder kind of abuse!

--
Cheers,

John.

/=================================================================\
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\=================================================================/

In article <tijjan$3erje$5@dont-email.me>, John Rumm
<see.my.signature@nowhere.null> wrote:
> On 17/10/2022 03:11, Animal wrote:
> > On Sunday, 16 October 2022 at 00:59:00 UTC+1, John Rumm wrote:
> >> On 15/10/2022 17:15, Graham wrote: Gosh a 17yo thread has popped back
> >> into life from the 16th edition!
> >>> Why does it need upgrading to MCBs ?? I have an old Wylex consumer
> >>> unit containing wire fuses . All you need do is buy a stand alone RCD
> >>> install it before the fuse box and hey presto ! your whole
> >>> installation
> >> Yes, an installation that was a fairly crap idea during the 15th
> >> edition of BS7671 (which is the last time that practice would have
> >> been considered acceptable). It can potentially results in lots of
> >> nuisance RCD trips, and offers *no* discrimination at all in the even
> >> of a earth leakage fault.
> >>> , no matter how old is protected. I am a retired spark and have
> >>> lived in my house for 36 yrs and never felt the need to upgrade to
> >>> MCBs and have never had to change a fuse even once !!so
> >> Nothing inherently wrong with fuses as such, but "re-wireable" BS3036
> >> fuses have both usability and potential abuse issues.
> >
> > Breakers are also abusable. Seen people turn one back on time after
> > time after time when there was clearly a problem.

> Indeed - but not quite in the same league as fitting the foil from a
> fag box round the fuse, or a nail in the fuse holder kind of abuse!

1/4" pot metal spindle was the right diameter tor a plug fuse.

--
from KT24 in Surrey, England - sent from my RISC OS 4té
"I'd rather die of exhaustion than die of boredom" Thomas Carlyle

On 18/10/2022 09:30, charles wrote:
> In article <tijjan$3erje$5@dont-email.me>, John Rumm
> <see.my.signature@nowhere.null> wrote:
>> On 17/10/2022 03:11, Animal wrote:
>>> On Sunday, 16 October 2022 at 00:59:00 UTC+1, John Rumm wrote:
>>>> On 15/10/2022 17:15, Graham wrote: Gosh a 17yo thread has popped back
>>>> into life from the 16th edition!
>>>>> Why does it need upgrading to MCBs ?? I have an old Wylex consumer
>>>>> unit containing wire fuses . All you need do is buy a stand alone RCD
>>>>> install it before the fuse box and hey presto ! your whole
>>>>> installation
>>>> Yes, an installation that was a fairly crap idea during the 15th
>>>> edition of BS7671 (which is the last time that practice would have
>>>> been considered acceptable). It can potentially results in lots of
>>>> nuisance RCD trips, and offers *no* discrimination at all in the even
>>>> of a earth leakage fault.
>>>>> , no matter how old is protected. I am a retired spark and have
>>>>> lived in my house for 36 yrs and never felt the need to upgrade to
>>>>> MCBs and have never had to change a fuse even once !!so
>>>> Nothing inherently wrong with fuses as such, but "re-wireable" BS3036
>>>> fuses have both usability and potential abuse issues.
>>>
>>> Breakers are also abusable. Seen people turn one back on time after
>>> time after time when there was clearly a problem.
>
>> Indeed - but not quite in the same league as fitting the foil from a
>> fag box round the fuse, or a nail in the fuse holder kind of abuse!
>
> 1/4" pot metal spindle was the right diameter tor a plug fuse.

My dad's lathe kept popping fuses on start-up. The fuse was replaced by
a peice of a drill. To be fair, the lathe feed was still protected by a
16A MCB in the shed it is in and (IIRC) a 20A MCB feeding that from the
house, so a plug fuse was not really necessary.

On 18/10/2022 16:00, SteveW wrote:
> On 18/10/2022 09:30, charles wrote:
>> In article <tijjan$3erje$5@dont-email.me>, John Rumm
>> <see.my.signature@nowhere.null> wrote:
>>> On 17/10/2022 03:11, Animal wrote:
>>>> On Sunday, 16 October 2022 at 00:59:00 UTC+1, John Rumm wrote:
>>>>> On 15/10/2022 17:15, Graham wrote: Gosh a 17yo thread has popped back
>>>>> into life from the 16th edition!
>>>>>> Why does it need upgrading to MCBs ??  I have an old Wylex consumer
>>>>>> unit containing wire fuses . All you need do is buy a stand alone RCD
>>>>>> install it before the fuse box and hey presto !  your whole
>>>>>> installation
>>>>> Yes, an installation that was a fairly crap idea during the 15th
>>>>> edition of BS7671 (which is the last time that practice would have
>>>>> been considered acceptable). It can potentially results in lots of
>>>>> nuisance RCD trips, and offers *no* discrimination at all in the even
>>>>> of a earth leakage fault.
>>>>>> , no matter how old is protected.  I am a retired spark and have
>>>>>> lived in my house for 36 yrs and never felt the need to upgrade to
>>>>>> MCBs and have never had to change a fuse even once !!so
>>>>> Nothing inherently wrong with fuses as such, but "re-wireable" BS3036
>>>>> fuses have both usability and potential abuse issues.
>>>>
>>>> Breakers are also abusable. Seen people turn one back on time after
>>>> time after time when there was clearly a problem.
>>
>>> Indeed - but not quite in the same league as fitting the foil  from a
>>> fag box round the fuse, or a nail in the fuse holder kind of abuse!
>>
>> 1/4" pot metal spindle was the right diameter tor a plug fuse.
>
> My dad's lathe kept popping fuses on start-up. The fuse was replaced by
> a peice of a drill. To be fair, the lathe feed was still protected by a
> 16A MCB in the shed it is in and (IIRC) a 20A MCB feeding that from the
> house, so a plug fuse was not really necessary.

Probably an induction motor - so inrush can be 5 to 9 times the normal
operating current.

It is a bit hit and miss if I try and power up my 3kVA site transformer
(with no load) on even a 20A MCB for the same reason.

--
Cheers,

John.

/=================================================================\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\=================================================================/

SteveW <steve@walker-family.me.uk> wrote:
> >> Indeed - but not quite in the same league as fitting the foil from a
> >> fag box round the fuse, or a nail in the fuse holder kind of abuse!
> >
> > 1/4" pot metal spindle was the right diameter tor a plug fuse.
>
> My dad's lathe kept popping fuses on start-up. The fuse was replaced by
> a peice of a drill. To be fair, the lathe feed was still protected by a
> 16A MCB in the shed it is in and (IIRC) a 20A MCB feeding that from the
> house, so a plug fuse was not really necessary.
>
That sounds odd. A 13 amp fuse will almost always last longer than a
16 amp MCB. It takes a whole lot more than 13 amps to blow a 13 amp
plug fuse where as, if the motor was really taking a big lump of
current at start up I would expect the MCB to trip.

--
Chris Green
·

On 18/10/2022 17:03, Chris Green wrote:
> SteveW <steve@walker-family.me.uk> wrote:
>>>> Indeed - but not quite in the same league as fitting the foil from a
>>>> fag box round the fuse, or a nail in the fuse holder kind of abuse!
>>>
>>> 1/4" pot metal spindle was the right diameter tor a plug fuse.
>>
>> My dad's lathe kept popping fuses on start-up. The fuse was replaced by
>> a peice of a drill. To be fair, the lathe feed was still protected by a
>> 16A MCB in the shed it is in and (IIRC) a 20A MCB feeding that from the
>> house, so a plug fuse was not really necessary.
>>
> That sounds odd. A 13 amp fuse will almost always last longer than a
> 16 amp MCB. It takes a whole lot more than 13 amps to blow a 13 amp
> plug fuse where as, if the motor was really taking a big lump of
> current at start up I would expect the MCB to trip.

It definitely blew them regularly and without tripping either MCB.

The break bands for a 16A type C MCB and a 13A BS1362 fuse do cross at
the high end of the likely motor current, within the time taken getting
started - and the motor does have quite a load on startup if you've
forgotten to drop the lathe to its lowest speed before stopping it (it
uses a mechanical variable speed drive ... Raglan Litle John mk2).

On 18/10/2022 17:03, Chris Green wrote:
> SteveW <steve@walker-family.me.uk> wrote:
>>>> Indeed - but not quite in the same league as fitting the foil from a
>>>> fag box round the fuse, or a nail in the fuse holder kind of abuse!
>>>
>>> 1/4" pot metal spindle was the right diameter tor a plug fuse.
>>
>> My dad's lathe kept popping fuses on start-up. The fuse was replaced by
>> a peice of a drill. To be fair, the lathe feed was still protected by a
>> 16A MCB in the shed it is in and (IIRC) a 20A MCB feeding that from the
>> house, so a plug fuse was not really necessary.
>>
> That sounds odd. A 13 amp fuse will almost always last longer than a
> 16 amp MCB. It takes a whole lot more than 13 amps to blow a 13 amp
> plug fuse where as, if the motor was really taking a big lump of
> current at start up I would expect the MCB to trip.

I think this is one of those cases where if you look at the typical trip
curves, there is a nice gap where the fuse can fail before the MCB.

A B16 MCB will have a fault current trip of 80A. So below that threshold
you are on the normal thermal response, and a MCB has much more thermal
mass in its bimetal strip than in a fuse.

Say your inrush is 40A, the MCB could take 60 secs to clear that. A 13A
fuse in a plug won't last 10 secs (maximum) at that load, and will more
likely be down at the sub 100ms kind of time.

So unless the lath can pull an inrush that is above the fault current
threshold of the MCB, it is unlikely to trip it (given it will only pull
that current for a very short time).

--
Cheers,

John.

/=================================================================\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\=================================================================/