On 24/03/2021 20:05, Fredxx wrote:
On 24/03/2021 18:41, Theo wrote:
Tim+ wrote:
yy ARW wrote:

Loose connections.

+1.Â* Not appropriately torqued I would guess.
(a common problem with electric showers, which tend to run for a much
shorter time)

It's possible a load 32A was applied which melted the isolator and
cooked
the RCD, but I would expect the MCB to trip for that.Â* It could be a
faulty
or fake MCB I suppose.

Cheers. Is there anything wrong with the positioning of the MCB as
suggested by Adrian?

It really depends on how the charger is set up, which we can't see.
Chargers can be set to monitor the outputs from the consumer unit and
limit
the current if another big load like a shower or cooker is in use, so
that
the maximum current of the supply is not exceeded.Â* Alternatively the
electrician can apply diversity to set the charger output to a lower
current.

I don't know the rating of that busbar, but I'd expect it to carry the
full
current from the main switch if it were wired that way.Â* So I don't
think an
80A RCD next to a 32A MCB should cause any problems (apart from perhaps
running warm and gradual cookage over time).

I may be wrong, but I thought each busbar was only rated for 60A for a
100A CU. With the presumption that the load would be split more or less
equally to both sides of the CU.

Unlikely. My CU can be fitted with split busbars (of varying length) for
RCD use or a single busbar for non-RCD use/RCBOs. The size of the busbar
is the same in all cases - as indeed it is for the larger boxes with
more ways. If split busbars are used, the second is fed, via the RCD,
from the first, whcih has to carry all the load on the unit.

I am pretty sure the highest rated circuit should be next the RCD, next
to the main switch.

That makes sense.

On 24/03/2021 18:33, alan_m wrote:
On 24/03/2021 18:28, alan_m wrote:

Have all the MCB levers been joined and cable tied in the on position?

OK - no. I had just zoomed in and that's what it looked like.

Even if they were, I presume (like the ones I used to specify at work),
that they are still capable of tripping if the lever cannot move.

On 24/03/2021 19:43, Andy Burns wrote:
Tim+ wrote:
This is the fuse box of a chap on Facebook who had a nasty experience
after
getting an 7kW EV charger fitted.

I dont know enough to speculate on the cause but it there anything
glaringly wrong here.

https://www.amazon.co.uk/photos/shar...9HHYn227WF3V0A


118A of MCBs on a 80A RCD, but I doubt all the circuits would be fully
loaded for long, are the righthand 32A MCBs both rings?

Assume the EV charger is on the leftmost MCB?Â* Looks more as though the
terminals onto the live busbar weren't properly tight ...

Just looking at the discolouration, I'd say the the terminal on the RCD
was definitely loose. The others may have been or it may have been heat
transferred along the busbar, from the RCD terminal.

On 24/03/2021 20:20, ARW wrote:
On 24/03/2021 20:05, Fredxx wrote:
On 24/03/2021 18:41, Theo wrote:
Tim+ wrote:
yy ARW wrote:

Loose connections.

+1.Â* Not appropriately torqued I would guess.
(a common problem with electric showers, which tend to run for a much
shorter time)

It's possible a load 32A was applied which melted the isolator and
cooked
the RCD, but I would expect the MCB to trip for that.Â* It could be a
faulty
or fake MCB I suppose.

Cheers. Is there anything wrong with the positioning of the MCB as
suggested by Adrian?

It really depends on how the charger is set up, which we can't see.
Chargers can be set to monitor the outputs from the consumer unit and
limit
the current if another big load like a shower or cooker is in use, so
that
the maximum current of the supply is not exceeded.Â* Alternatively the
electrician can apply diversity to set the charger output to a lower
current.

I don't know the rating of that busbar, but I'd expect it to carry
the full
current from the main switch if it were wired that way.Â* So I don't
think an
80A RCD next to a 32A MCB should cause any problems (apart from perhaps
running warm and gradual cookage over time).

I may be wrong, but I thought each busbar was only rated for 60A for a
100A CU. With the presumption that the load would be split more or
less equally to both sides of the CU.

I am pretty sure the highest rated circuit should be next the RCD,
next to the main switch.

If I was the OP I would check the position of this MCB, after all it
be the one with the highest continuous current, and check with the CU
manufacturer's installation guide.


You are going back to the days of Wylex fuse boards. They always had
that rule and some of them had an extra fuse to the right of the main
switch for high loads.

The Wylex CU in the photo will have no problem with the layout of the
MCBs and is good for 100A.

I bow to your greater knowledge :-)

On 24/03/2021 19:04, Fredxx wrote:
On 24/03/2021 18:50, The Natural Philosopher wrote:
On 24/03/2021 18:07, Tim+ wrote:
Also, is that burnt out isolator switch suitable for a 7kW load over
8 hrs
say (as might occur when car charging)?

I doubt it.

It doesn't look 30A capable - you need at least 25A for 7Kw

The one in the photo has Omega markings and looks like this:
Â* https://rpp.uk.com/product/45a-double-pole-switches/

It has a 45A rating, and unless you can convince me otherwise it will be
continuously rated.

It looks like it failed first though and then cooked the distribution
panel. The damage to it is way too much for it to be an innocent
bystander. It was most likely the root cause and drew enough current to
damage other components but not quite enough to trigger a fast cutout.

One terminal is essentially completely burnt away. That is *really* hot!

--
Regards,
Martin Brown

On 24 Mar 2021 at 21:57:02 GMT, "Steve Walker"
wrote:

On 24/03/2021 19:43, Andy Burns wrote:
Tim+ wrote:
This is the fuse box of a chap on Facebook who had a nasty experience
after
getting an 7kW EV charger fitted.

I dont know enough to speculate on the cause but it there anything
glaringly wrong here.


https://www.amazon.co.uk/photos/shar...9HHYn227WF3V0A



118A of MCBs on a 80A RCD, but I doubt all the circuits would be fully
loaded for long, are the righthand 32A MCBs both rings?

Assume the EV charger is on the leftmost MCB?Â* Looks more as though the
terminals onto the live busbar weren't properly tight ...

Just looking at the discolouration, I'd say the the terminal on the RCD
was definitely loose. The others may have been or it may have been heat
transferred along the busbar, from the RCD terminal.

Could the busbar be the wrong side of the terminal in the RCD, or can't you do
that with modern kit?

--
Roger Hayter

On 24/03/2021 22:17, Martin Brown wrote:
On 24/03/2021 19:04, Fredxx wrote:
On 24/03/2021 18:50, The Natural Philosopher wrote:
On 24/03/2021 18:07, Tim+ wrote:
Also, is that burnt out isolator switch suitable for a 7kW load over
8 hrs
say (as might occur when car charging)?

I doubt it.

It doesn't look 30A capable - you need at least 25A for 7Kw

The one in the photo has Omega markings and looks like this:
Â*Â* https://rpp.uk.com/product/45a-double-pole-switches/

It has a 45A rating, and unless you can convince me otherwise it will
be continuously rated.

It looks like it failed first though and then cooked the distribution
panel. The damage to it is way too much for it to be an innocent
bystander. It was most likely the root cause and drew enough current to
damage other components but not quite enough to trigger a fast cutout.

One terminal is essentially completely burnt away. That is *really* hot!

Both defects looked as if they occurred simultaneously, the switch was
the first to let go.

I don't believe the heat travelled up the cable to the consumer unit, or
that the switch caused an increased load?

At a guess the charring temperature of plastic is quite low, ~200C when
carbonisation starts to occur.

Martin Brown wrote:
It looks like it failed first though and then cooked the distribution
panel. The damage to it is way too much for it to be an innocent
bystander. It was most likely the root cause and drew enough current to
damage other components but not quite enough to trigger a fast cutout.

One terminal is essentially completely burnt away. That is *really* hot!

I'm not sure I quite buy that. If everything was making good connections,
you would need:

1. The isolator to fail short circuit between line and neutral. That would
seem to be a really bad failure mode for an isolator, but OK let's assume it
did
2. It fails taking 32A but less than the trip current/time of the MCB.
3. That current is sufficient to cook the busbar in a short enough time
before the MCB tripped (eg 4x rated current it should trip in 10 seconds if
I read the graph right)

The MCB is rated for a short circuit current of 6kA so I would be surprised
for it to cook rather than simply open and continue with its day.
Similarly the RCD should be able to pass 80A with no heating.

If, however, the connections at both ends were high(er) resistance by being
incorrectly installed, that would cause heating of both the isolator and the
busbar. That could happen in normal operation, a condition which wouldn't
trip anything as it's all under the rated current.

Theo

On 24/03/2021 21:15, Andy Burns wrote:
Tim+ wrote:

is that burnt out isolator switch suitable for a 7kW load over 8 hrs

Looks like 45A so should be ok, but why fit it in the first place?


https://www.cef.co.uk/catalogue/products/1850955-1-gang-45a-double-pole-switch-white

a 45A cooker switch wont necessarily take all the cooker elements on and
heating up, for 6 hours...every day.


--
"Nature does not give up the winter because people dislike the cold."

ۥ Confucius

The Natural Philosopher wrote:

a 45A cooker switch wont necessarily take all the cooker elements on and
heating up, for 6 hours...every day.

Even if fitted in a commercial kitchen? Yes I suspect such kitchens
would typically have 3ph ovens and would have more chunky isolators, but
where does a 45A isolator say "not for continuous use"?

Surprisingly BSEN 60669-1:2000 doesn't appear to have anything to say on
that.

Andy Burns wrote:
The Natural Philosopher wrote:

a 45A cooker switch wont necessarily take all the cooker elements on and
heating up, for 6 hours...every day.

Even if fitted in a commercial kitchen? Yes I suspect such kitchens
would typically have 3ph ovens and would have more chunky isolators, but
where does a 45A isolator say "not for continuous use"?

Surprisingly BSEN 60669-1:2000 doesn't appear to have anything to say on
that.


One feels it ought to. A 13amp plug & socket might well be fine for a
while, but if you try to draw 13amps for long periods you soon find out
that they overheat. EV makers are well aware of this and their €œgranny
leads€� for use in standard sockets are limited to 2.2kW.

Tim

--
Please don't feed the trolls

On 24/03/2021 22:17, Martin Brown wrote:
On 24/03/2021 19:04, Fredxx wrote:
On 24/03/2021 18:50, The Natural Philosopher wrote:
On 24/03/2021 18:07, Tim+ wrote:
Also, is that burnt out isolator switch suitable for a 7kW load over
8 hrs
say (as might occur when car charging)?

I doubt it.

It doesn't look 30A capable - you need at least 25A for 7Kw

The one in the photo has Omega markings and looks like this:
Â*Â* https://rpp.uk.com/product/45a-double-pole-switches/

It has a 45A rating, and unless you can convince me otherwise it will
be continuously rated.

It looks like it failed first though and then cooked the distribution
panel. The damage to it is way too much for it to be an innocent
bystander. It was most likely the root cause and drew enough current to
damage other components but not quite enough to trigger a fast cutout.

One terminal is essentially completely burnt away. That is *really* hot!


Here is another fusebox, burnt in a similar place. (left image in this
frozen youtube clip).

https://www.youtube.com/watch?v=HMNmav9Gr7A&t=296s

When installing these things onto busbars, ye can either fail to
correctly tighten them, or completely misalign the busbar 'tang' so that
it friction hits the outside body of the terminal rather than the cavity
inside, the tightened screw gripping onto nothing.

--
Adrian C

On 24/03/2021 23:05, Fredxx wrote:
On 24/03/2021 22:17, Martin Brown wrote:
On 24/03/2021 19:04, Fredxx wrote:
On 24/03/2021 18:50, The Natural Philosopher wrote:
On 24/03/2021 18:07, Tim+ wrote:
Also, is that burnt out isolator switch suitable for a 7kW load
over 8 hrs
say (as might occur when car charging)?

I doubt it.

It doesn't look 30A capable - you need at least 25A for 7Kw

The one in the photo has Omega markings and looks like this:
Â*Â* https://rpp.uk.com/product/45a-double-pole-switches/

It has a 45A rating, and unless you can convince me otherwise it will
be continuously rated.

It looks like it failed first though and then cooked the distribution
panel. The damage to it is way too much for it to be an innocent
bystander. It was most likely the root cause and drew enough current
to damage other components but not quite enough to trigger a fast cutout.

One terminal is essentially completely burnt away. That is *really* hot!

Both defects looked as if they occurred simultaneously, the switch was
the first to let go.

I don't believe the heat travelled up the cable to the consumer unit, or
that the switch caused an increased load?

At a guess the charring temperature of plastic is quite low, ~200C when
carbonisation starts to occur.


If the electrician was a bit timid about tightening the screws on the
consumer unit, you'd think he was probably equally timid about
tightening them on the switch, too. They are both carrying the same
current. So, I really can't see any reason to look for anything more
complicated as an explanation.

I'm interested to know whether electricians routinely use torque
screwdrivers, or just rely on experience?

GB wrote:

I'm interested to know whether electricians routinely use torque
screwdrivers, or just rely on experience?

Judging by those who put their jobs on youtube, it's now quite common,
and CUs etc include required torque settings.

Whether the old hands bother or "know better" ...

Andy Burns wrote:
Even if fitted in a commercial kitchen? Yes I suspect such kitchens
would typically have 3ph ovens and would have more chunky isolators, but
where does a 45A isolator say "not for continuous use"?

Surprisingly BSEN 60669-1:2000 doesn't appear to have anything to say on
that.

I would expect the isolator to be rated for continuous use. However the
electrician, who may have done a lot of cooker and shower circuits in the
past but be new to EVs, may have got away with insufficiently torqued screws
since cookers and showers don't draw currents for long periods.

(even in a commercial kitchen, you might draw max current when cold but once
the ovens/rings are up to temperature the load will reduce, and the
likelihood of all the rings and ovens running from cold at the same time is
small)

Theo

On 25/03/2021 11:46, Andy Burns wrote:

GB wrote:

I'm interested to know whether electricians routinely use torque
screwdrivers, or just rely on experience?

Judging by those who put their jobs on youtube, it's now quite common,
and CUs etc include required torque settings.

Whether the old hands bother or "know better" ...

They're not cheap.

Given the way motor mechanics now regularly use torque wrenches on
anything critical I suspect there will be creep towards electricians
using them.

As I said earlier, if you are seen to use one regularly then it does
reduce some aspects of liability and litigation.

It also helps calibrate the wrist, I for one have no idea how much I
tighten screws. I tend to nip up the screw on the cable and end at some
point when I feel failure is likely or where the blade will slip out of
the screw.

Fredxx wrote:

GB wrote:

I'm interested to know whether electricians routinely use torque
screwdrivers

They're not cheap.

Should they buy their own torque analyzer, or send their screwdrivers
off for annual calibration checking like they do their meters?

https://gedore-torque.com/product/capture-hub-torque-analyser

On 25/03/2021 12:55, Fredxx wrote:

They're not cheap.

Given the way motor mechanics now regularly use torque wrenches on
anything critical I suspect there will be creep towards electricians
using them.

As I said earlier, if you are seen to use one regularly then it does
reduce some aspects of liability and litigation.

It also helps calibrate the wrist, I for one have no idea how much I
tighten screws. I tend to nip up the screw on the cable and end at some
point when I feel failure is likely or where the blade will slip out of
the screw.


You need the BMW tightness test.

#1. Hand tight
#2. BMW torque tight
#3. broken

If in doubt, tighten to #3 and then back it off a quarter turn ...

FWIW I've seen torque settings specified for screws inside mobile phones
and laptops.

--
Adrian C

On 25/03/2021 13:13, Andy Burns wrote:
Fredxx wrote:

GB wrote:

I'm interested to know whether electricians routinely use torque
screwdrivers

They're not cheap.

Should they buy their own torque analyzer, or send their screwdrivers
off for annual calibration checking like they do their meters?

https://gedore-torque.com/product/capture-hub-torque-analyser

Overly complicated when all you need is a bar with a hole and a screw to
clamp to the screwdriver and a mass that can be positioned anywhere
along the bar and you can check calibration at as many points as you like.

Simple calculation for the effect of the bar itself and then add the
torque due to the mass at whatever distance from the screwdriver.

On 25/03/2021 13:40, Steve Walker wrote:
On 25/03/2021 13:13, Andy Burns wrote:
Fredxx wrote:

GB wrote:

I'm interested to know whether electricians routinely use torque
screwdrivers

They're not cheap.

Should they buy their own torque analyzer, or send their screwdrivers
off for annual calibration checking like they do their meters?

https://gedore-torque.com/product/capture-hub-torque-analyser

Overly complicated when all you need is a bar with a hole and a screw to
clamp to the screwdriver and a mass that can be positioned anywhere
along the bar and you can check calibration at as many points as you like.

Simple calculation for the effect of the bar itself and then add the
torque due to the mass at whatever distance from the screwdriver.

In fact. Make the hole at the centre of the bar, so that it is self
balancing and you don't even have to allow for the effect of the bar
itself at all.

In article ,
Fredxx wrote:
On 24/03/2021 18:00, Tim+ wrote:
Scott wrote:
On 24 Mar 2021 17:43:56 GMT, Tim+ wrote:

Adrian Caspersz wrote:


That fusebox not made for that overload on that leg, maybe it should
have been installed on the right (full picture please!)

It’s been replaced now and I don’t think there are more pictures.

By a different electrician I hope?


Nope. Same one (which concerns me!).

Did you check if he used a torque screwdriver?

If he did, and he claim to have used the correct settings, he'll
effectively be absolved from blame.

Crikey. I just tighten them till they groan. And never ever had a terminal
screw come lose. But seen plenty on other installations.

--
*When you get a bladder infection urine trouble.*

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

In article ,
Michael Chare wrote:
If I installed a 7kw electric car charger it would likely draw more
continuous current than any (maybe all) other device in my house. I
would think this would be true for many properties.

Not as much as the CU draws from the incoming mains. ;-)

--
*Virtual reality is its own reward *

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

On 25/03/2021 10:15, Adrian Caspersz wrote:
On 24/03/2021 22:17, Martin Brown wrote:
On 24/03/2021 19:04, Fredxx wrote:
On 24/03/2021 18:50, The Natural Philosopher wrote:
On 24/03/2021 18:07, Tim+ wrote:
Also, is that burnt out isolator switch suitable for a 7kW load
over 8 hrs
say (as might occur when car charging)?

I doubt it.

It doesn't look 30A capable - you need at least 25A for 7Kw

The one in the photo has Omega markings and looks like this:
Â*Â* https://rpp.uk.com/product/45a-double-pole-switches/

It has a 45A rating, and unless you can convince me otherwise it will
be continuously rated.

It looks like it failed first though and then cooked the distribution
panel. The damage to it is way too much for it to be an innocent
bystander. It was most likely the root cause and drew enough current
to damage other components but not quite enough to trigger a fast cutout.

One terminal is essentially completely burnt away. That is *really* hot!


Here is another fusebox, burnt in a similar place. (left image in this
frozen youtube clip).

https://www.youtube.com/watch?v=HMNmav9Gr7A&t=296s


3min55sec. He says its PME with no label. It's labelled PME on the
bottom left.



--
Adam

He does not work for Hollywood special effects does he? Have you ever
noticed that in films when all the lights fail there are bangs and sizzles
and sparks out of a fuse box when they do? I've never had that happen to me,
its usually good old short circuits and a main fuse goes. Unless of course
your house gets struck by lightning but that is not the scenario. I cannot
see your example but it always worries me when something daft happens to
somebody I do not know from Adam!

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.!
"Tim+" wrote in message
...
This is the fuse box of a chap on Facebook who had a nasty experience
after
getting an 7kW EV charger fitted.

I don't know enough to speculate on the cause but it there anything
glaringly wrong here.

https://www.amazon.co.uk/photos/shar...9HHYn227WF3V0A

Tim


--
Please don't feed the trolls

Ha haa, there has to be a joke there somewhere....
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.!
"Andrew" wrote in message
...
On 24/03/2021 17:24, Tim+ wrote:
Tim+ wrote:
This is the fuse box of a chap on Facebook who had a nasty experience
after
getting an 7kW EV charger fitted.

I don't know enough to speculate on the cause but it there anything
glaringly wrong here.

https://www.amazon.co.uk/photos/shar...9HHYn227WF3V0A

Tim



A couple more pictures.

https://www.amazon.co.uk/photos/shar...I0kDlJqRD9xrqI

https://www.amazon.co.uk/photos/shar...LdCEBmhpwfUb8j

Tim


Do you need an Amazon Prime account to post these pics ?

On 25/03/2021 13:21, Adrian Caspersz wrote:
On 25/03/2021 12:55, Fredxx wrote:

They're not cheap.

Given the way motor mechanics now regularly use torque wrenches on
anything critical I suspect there will be creep towards electricians
using them.

As I said earlier, if you are seen to use one regularly then it does
reduce some aspects of liability and litigation.

It also helps calibrate the wrist, I for one have no idea how much I
tighten screws. I tend to nip up the screw on the cable and end at
some point when I feel failure is likely or where the blade will slip
out of the screw.


You need the BMW tightness test.

#1. Hand tight
#2. BMW torque tight
#3. broken


#4. Kwikfit gorilla tight, making it difficult to remove with even
a 4-foot bar on the wheel socket. (As my neighbour discovered not too
long ago).

On 24/03/2021 18:50, The Natural Philosopher wrote:
On 24/03/2021 18:07, Tim+ wrote:
Also, is that burnt out isolator switch suitable for a 7kW load over 8
hrs
say (as might occur when car charging)?

I doubt it.


It doesn't look 30A capable - you need at least 25A for 7Kw

That's a cooker switch or better, and cooker switches don't have to meet
continuous load.

Id go for a more industrial thing

https://www.screwfix.com/p/british-g...itch-63a/8536r


and underrate it like fanny.


and which makes it an absolute doddle to isolate+lockoff and/or to
secure the charger to stop someone stealing your juice.

John Kenyon wrote:
On 24/03/2021 18:50, The Natural Philosopher wrote:
On 24/03/2021 18:07, Tim+ wrote:
Also, is that burnt out isolator switch suitable for a 7kW load over 8
hrs
say (as might occur when car charging)?

I doubt it.


It doesn't look 30A capable - you need at least 25A for 7Kw

That's a cooker switch or better, and cooker switches don't have to meet
continuous load.

Id go for a more industrial thing

https://www.screwfix.com/p/british-g...itch-63a/8536r


and underrate it like fanny.


and which makes it an absolute doddle to isolate+lockoff and/or to
secure the charger to stop someone stealing your juice.

Like someone is going to pull into your drive, plug in for X hours and then
drive away again? Not something Im gonna lose sleep over.

Tim

--
Please don't feed the trolls