Hi all,

I've recently had a consumer unit replaced in my flat, moving from cartridge fuses to RCBOs.

Following this, it looks like I may have an earth problem. While loading the dishwasher, I was leaning on the worktop with my hand on the stainless steel sink. On touching the inside of the diskwasher, I got a tingle.

So, I got out my multimeter and an extension cable and did some checks.

The potential difference between the inside of the dishwasher and the sink is approximately 55 to 60 VAC.

Checking the earth of the socket the d/w was plugged into, it too has a PD of about 55-60 VAC with the sink.

So I checked back to the heating radiators, and the PD between the electrical earth in the socket service the d/w and the radiators is alos approx 55-60 VAC.

Checked the same back to the main water incomer - also PD of 55-60 VAC.

Now, the d/w is on a separate way to other equipment in the kitchen, so I checked other kitchen sockets, and yes, you've guessed it, PD of about 55-60 VAC between electrical earth presented at the socket and the water pipes. And the same with stuff on yet another way in the consumer unit.

Is this normal for a an installation after RCBOs are installed? (I suspect not, but it would be nice to have this confirmed).

If not normal, what's the likely cause? Obviously, I'll need to get the professional electrician back who installed the new consumer unit, but I want to make sure I ask the right questions. Is it possible to simply forget to connect the protective earth through the consumer unit, so the 'downstream' side simply has a floating earth? So it could be a simple 'forgot to connect up a final wire'? That is, a could a missing single connection affect all ways?

As it is a block of flats, my consumer unit is in a set of cupboards next to each other in the common corridor outside the flats - one consumer unit per cupboard. The neighbours have not replaced their cartridge fuse consumer units, so still have an exposed earth terminal in their cupboards, and I was able to confirm that the all the metal cupboards (including mine) are connected to a protective earth which has zero PD with respect to the water pipes.

The RCBO protecting the d/w is a snazzy EATON one, which can give an indication of the leakage current it sees by flashing a multicoloured LED in a code in 'test mode'. On testing this, it gives a suspicious (to me) reading of 0 mA leakage; as does the RCBO covering the other kitchen equipment. To me, this seems to good to be true.

Comments and advice welcome, if if someone tells me I'm worrying over nothing.

Many thnaks,

Sid

On 02/03/14 23:12, wrote:
Hi all,

I've recently had a consumer unit replaced in my flat, moving from
cartridge fuses to RCBOs.

Following this, it looks like I may have an earth problem. While
loading the dishwasher, I was leaning on the worktop with my hand on
the stainless steel sink. On touching the inside of the diskwasher, I
got a tingle.

So, I got out my multimeter and an extension cable and did some
checks.

The potential difference between the inside of the dishwasher and the
sink is approximately 55 to 60 VAC.

Yes - you have an earthing problem somewhere.

Either your plumbing is earthed (directly or indirectly) and your main
earth is missing, or your plumbing is not earthed at all.


Checking the earth of the socket the d/w was plugged into, it too has
a PD of about 55-60 VAC with the sink.

So I checked back to the heating radiators, and the PD between the
electrical earth in the socket service the d/w and the radiators is
alos approx 55-60 VAC.

Checked the same back to the main water incomer - also PD of 55-60
VAC.

Now, the d/w is on a separate way to other equipment in the kitchen,
so I checked other kitchen sockets, and yes, you've guessed it, PD of
about 55-60 VAC between electrical earth presented at the socket and
the water pipes. And the same with stuff on yet another way in the
consumer unit.

Is this normal for a an installation after RCBOs are installed? (I
suspect not, but it would be nice to have this confirmed).

Nope - someones dropped a connection somewhere. RCBO's make no
measurable difference to the bonding.

If not normal, what's the likely cause? Obviously, I'll need to get
the professional electrician back who installed the new consumer
unit, but I want to make sure I ask the right questions. Is it
possible to simply forget to connect the protective earth through the
consumer unit, so the 'downstream' side simply has a floating earth?
So it could be a simple 'forgot to connect up a final wire'? That is,
a could a missing single connection affect all ways?

As it is a block of flats, my consumer unit is in a set of cupboards
next to each other in the common corridor outside the flats - one
consumer unit per cupboard. The neighbours have not replaced their
cartridge fuse consumer units, so still have an exposed earth
terminal in their cupboards, and I was able to confirm that the all
the metal cupboards (including mine) are connected to a protective
earth which has zero PD with respect to the water pipes.


That sounds like your main earth is missing - which is very very bad!

It's hard to be sure by a written account - but if I were you I would
call the electrician back asap. Or any electrician.

There's no way the installation should have been left with incorrect
earthing (either main earthing failure or bonding failure) - that's why
they (should) test after a CU upgrade!

On 02/03/14 23:32, Tim Watts wrote:

That sounds like your main earth is missing - which is very very bad!

It's hard to be sure by a written account - but if I were you I would
call the electrician back asap. Or any electrician.

And until you do that stay out of the shower.

On Monday, 3 March 2014 00:21:01 UTC, pcb1962 wrote:

And until you do that stay out of the shower.

+1

You have done some very nice diagnostics. The observation that your water pipes appear to be bonded to the metal cupboards in the corridor very strongly suggests that it is your main earthing connection in the new consumer unit that is missing.

A faulty appliance shorting live to "earth" would leave all metal appliances live relative to your plumbing. One of your RCBOs might trip from the leakage current in the system, but not necessarily until you completed the circuit with your body at some time later. You would then get an unpleasant but probably non-fatal shock in the short time before the RCBO trips.

Your electrician will want to come very quickly to remedy this. He will definitely not want his competitors or whatever body he is registered with to find out that he has made such a basic mistake compounded with failing to test the installation.

John

On 03/03/14 08:27, wrote:
On Monday, 3 March 2014 00:21:01 UTC, pcb1962 wrote:

And until you do that stay out of the shower.

+1

You have done some very nice diagnostics. The observation that your
water pipes appear to be bonded to the metal cupboards in the
corridor very strongly suggests that it is your main earthing
connection in the new consumer unit that is missing.

It does seem quite likely doesn't it.

A faulty appliance shorting live to "earth" would leave all metal
appliances live relative to your plumbing. One of your RCBOs might
trip from the leakage current in the system, but not necessarily
until you completed the circuit with your body at some time later.
You would then get an unpleasant but probably non-fatal shock in the
short time before the RCBO trips.

Your electrician will want to come very quickly to remedy this. He
will definitely not want his competitors or whatever body he is
registered with to find out that he has made such a basic mistake
compounded with failing to test the installation.

Personally, I would call in another electrician if I suspected this -
and I would ask him to document what was found.

Then I would get on the phone to the original electrician's professional
body (probably NICEIC, could be NAPIT or ELECSA or less likely a couple
of others).

Because if this transpires to be the cause, there is NO EXECUSE for
leaving an installation like this.

It's a mistake compounded with no testing at the end.

used his keyboard to write :
Hi all,

I've recently had a consumer unit replaced in my flat, moving from cartridge
fuses to RCBOs.

Following this, it looks like I may have an earth problem. While loading the
dishwasher, I was leaning on the worktop with my hand on the stainless steel
sink. On touching the inside of the diskwasher, I got a tingle.

It reads as if you potentially have a rather serious problem and my
first question is - was the guy who did the job actually qualified to
do it? Having completed the job, he should have carried out tests,
which would have highlighted this issue.

The voltage or potential difference, could be due to lack of an earth
at your sockets, or it could be that there is potential on your
pipework.

In other words you could be getting the tingle from the pipes, rather
than from the dishwasher. To prove which, connect a meter probe between
a length of metal pushed into the soil and measure between that and
pipes then dishwaher. Which ever test shows voltage, is obviously
lacking an adequate earth.

--
Regards,
Harry (M1BYT) (L)
http://www.ukradioamateur.co.uk

On 03/03/14 10:19, Harry Bloomfield wrote:
used his keyboard to write :
Hi all,

I've recently had a consumer unit replaced in my flat, moving from
cartridge fuses to RCBOs.

Following this, it looks like I may have an earth problem. While
loading the dishwasher, I was leaning on the worktop with my hand on
the stainless steel sink. On touching the inside of the diskwasher, I
got a tingle.

It reads as if you potentially have a rather serious problem and my
first question is - was the guy who did the job actually qualified to do
it? Having completed the job, he should have carried out tests, which
would have highlighted this issue.

The voltage or potential difference, could be due to lack of an earth at
your sockets, or it could be that there is potential on your pipework.

In other words you could be getting the tingle from the pipes, rather
than from the dishwasher. To prove which, connect a meter probe between
a length of metal pushed into the soil and measure between that and
pipes then dishwaher. Which ever test shows voltage, is obviously
lacking an adequate earth.


He did mention he'd tested to his neighbour's MET (main earth terminal)
as the consumer units are in a riser cupboard in the shared hallway.

Tim Watts wrote:
... very strongly suggests that it is your main earthing
connection in the new consumer unit that is missing.
Then I would get on the phone to the original electrician's professional
body (probably NICEIC,

Probably :-)

I had an entire landlord's supply left unearthed by a NICEIC registered firm. At least, it was their stickers everywhere.

Owain

Tim Watts wrote :
On 03/03/14 10:19, Harry Bloomfield wrote:
used his keyboard to write :
Hi all,

I've recently had a consumer unit replaced in my flat, moving from
cartridge fuses to RCBOs.

Following this, it looks like I may have an earth problem. While
loading the dishwasher, I was leaning on the worktop with my hand on
the stainless steel sink. On touching the inside of the diskwasher, I
got a tingle.

It reads as if you potentially have a rather serious problem and my
first question is - was the guy who did the job actually qualified to do
it? Having completed the job, he should have carried out tests, which
would have highlighted this issue.

The voltage or potential difference, could be due to lack of an earth at
your sockets, or it could be that there is potential on your pipework.

In other words you could be getting the tingle from the pipes, rather
than from the dishwasher. To prove which, connect a meter probe between
a length of metal pushed into the soil and measure between that and
pipes then dishwaher. Which ever test shows voltage, is obviously
lacking an adequate earth.


He did mention he'd tested to his neighbour's MET (main earth terminal) as
the consumer units are in a riser cupboard in the shared hallway.

I did realise that, but in a situation like this it is best not to
assume that anything can be relied upon, except the ground / soil, as a
valid reference point for earth.

--
Regards,
Harry (M1BYT) (L)
http://www.ukradioamateur.co.uk

Yes it may only be a not very well tightened screw somewhere, but it needs
fixing as it could get worse.
I've never noticed this with any electronic circuit breakers of any type as
they do not really have anything that can leak. Maybe pull them all and see
if it changes, but I doubt it.
Brian

--
From the Sofa of Brian Gaff Reply address is active
"pcb1962" wrote in message
...
On 02/03/14 23:32, Tim Watts wrote:

That sounds like your main earth is missing - which is very very bad!

It's hard to be sure by a written account - but if I were you I would
call the electrician back asap. Or any electrician.

And until you do that stay out of the shower.

submitted this idea :
Tim Watts wrote:
... very strongly suggests that it is your main earthing
connection in the new consumer unit that is missing.
Then I would get on the phone to the original electrician's professional
body (probably NICEIC,

Probably :-)

I had an entire landlord's supply left unearthed by a NICEIC registered firm.
At least, it was their stickers everywhere.

Owain

I would suggest NICEIC would have little or no interest. They are there
simply to collect money from the trade, rather than deal with
complaints from the public in regards to dangerous work carried out by
their registered tradesmen and contractors.

I would suggest involving a second independent engineer to actually
determine the cause and carry out repairs. He should also fully
document it - then recover the cost from your fist contractor via the
courts if necessary.

--
Regards,
Harry (M1BYT) (L)
http://www.ukradioamateur.co.uk

On 02/03/2014 23:12, wrote:
Hi all,

I've recently had a consumer unit replaced in my flat, moving from
cartridge fuses to RCBOs.

Following this, it looks like I may have an earth problem. While
loading the dishwasher, I was leaning on the worktop with my hand on
the stainless steel sink. On touching the inside of the diskwasher, I
got a tingle.

I would concur with the other diagnosis - you have a problem, and its
the electrician's job to fix it _NOW_ if not sooner.

So, I got out my multimeter and an extension cable and did some
checks.

The potential difference between the inside of the dishwasher and the
sink is approximately 55 to 60 VAC.

One typical source of floating voltages like this can be the noise
suppression input filters on the mains appliances. They often
capacitively couple the L & N to E. If the E connection is floating then
it will tend to try and sit somewhere about half mains potential. The
impedance is very high - so you are unable to get a shock from this
coupling, but you can feel it, and it is indicating some other problems
is present.

Checking the earth of the socket the d/w was plugged into, it too has
a PD of about 55-60 VAC with the sink.

So I checked back to the heating radiators, and the PD between the
electrical earth in the socket service the d/w and the radiators is
alos approx 55-60 VAC.

Checked the same back to the main water incomer - also PD of 55-60
VAC.

Now, the d/w is on a separate way to other equipment in the kitchen,
so I checked other kitchen sockets, and yes, you've guessed it, PD of
about 55-60 VAC between electrical earth presented at the socket and
the water pipes. And the same with stuff on yet another way in the
consumer unit.

Is this normal for a an installation after RCBOs are installed? (I
suspect not, but it would be nice to have this confirmed).

If not normal, what's the likely cause? Obviously, I'll need to get
the professional electrician back who installed the new consumer
unit, but I want to make sure I ask the right questions. Is it
possible to simply forget to connect the protective earth through the
consumer unit, so the 'downstream' side simply has a floating earth?

Its possible to forget (due to negligence / brain fart etc). It would be
impossible to not detect during testing however unless he did not test
it (gross negligence!)

You should have received a test sheet, that among other things would
indicate the Earth Loop Impedance (ELI) of each circuit. Did you get this?

So it could be a simple 'forgot to connect up a final wire'? That is,
a could a missing single connection affect all ways?

As it is a block of flats, my consumer unit is in a set of cupboards
next to each other in the common corridor outside the flats - one
consumer unit per cupboard. The neighbours have not replaced their
cartridge fuse consumer units, so still have an exposed earth
terminal in their cupboards, and I was able to confirm that the all
the metal cupboards (including mine) are connected to a protective
earth which has zero PD with respect to the water pipes.

Your main earth should also be bonded to this...

This implies that even if your main earth was not particularly good
(e.g. a TT earth*), you would not expect to see the difference between
circuit earths and the pipework etc.

* http://wiki.diyfaq.org.uk/index.php?title=TT_Earthing

The RCBO protecting the d/w is a snazzy EATON one, which can give an
indication of the leakage current it sees by flashing a multicoloured
LED in a code in 'test mode'. On testing this, it gives a suspicious
(to me) reading of 0 mA leakage; as does the RCBO covering the other
kitchen equipment. To me, this seems to good to be true.

Keep in mind the "leakage" it sees is only the imbalance between L & N.
The only bit of a DW that naturally shows leakages as such is a small
amount (possibly 1mA) for the input filtering, and perhaps a bit more
when the heater is working (depending on the age of the element) it will
not necessarily (depending on the flavour of RCBO) have any earth
connection, and be able to detect a rise in earth voltage.


Comments and advice welcome, if if someone tells me I'm worrying over
nothing.

Many thnaks,

Sid

All in all, congrats on a good set of diagnostics! ;-)



--
Cheers,

John.

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

On Sunday, March 2, 2014 11:12:59 PM UTC, wrote:
Hi all,



I've recently had a consumer unit replaced in my flat, moving from cartridge fuses to RCBOs.



Following this, it looks like I may have an earth problem. While loading the dishwasher, I was leaning on the worktop with my hand on the stainless steel sink. On touching the inside of the diskwasher, I got a tingle.



So, I got out my multimeter and an extension cable and did some checks.



The potential difference between the inside of the dishwasher and the sink is approximately 55 to 60 VAC.



Checking the earth of the socket the d/w was plugged into, it too has a PD of about 55-60 VAC with the sink.



So I checked back to the heating radiators, and the PD between the electrical earth in the socket service the d/w and the radiators is alos approx 55-60 VAC.



Checked the same back to the main water incomer - also PD of 55-60 VAC.



Now, the d/w is on a separate way to other equipment in the kitchen, so I checked other kitchen sockets, and yes, you've guessed it, PD of about 55-60 VAC between electrical earth presented at the socket and the water pipes.. And the same with stuff on yet another way in the consumer unit.



Is this normal for a an installation after RCBOs are installed? (I suspect not, but it would be nice to have this confirmed).



If not normal, what's the likely cause? Obviously, I'll need to get the professional electrician back who installed the new consumer unit, but I want to make sure I ask the right questions. Is it possible to simply forget to connect the protective earth through the consumer unit, so the 'downstream' side simply has a floating earth? So it could be a simple 'forgot to connect up a final wire'? That is, a could a missing single connection affect all ways?



As it is a block of flats, my consumer unit is in a set of cupboards next to each other in the common corridor outside the flats - one consumer unit per cupboard. The neighbours have not replaced their cartridge fuse consumer units, so still have an exposed earth terminal in their cupboards, and I was able to confirm that the all the metal cupboards (including mine) are connected to a protective earth which has zero PD with respect to the water pipes.



The RCBO protecting the d/w is a snazzy EATON one, which can give an indication of the leakage current it sees by flashing a multicoloured LED in a code in 'test mode'. On testing this, it gives a suspicious (to me) reading of 0 mA leakage; as does the RCBO covering the other kitchen equipment. To me, this seems to good to be true.



Comments and advice welcome, if if someone tells me I'm worrying over nothing.



Many thnaks,



Sid

Just a quick update. I've left the original text as context, apologies if I should have snipped some/all.

I have contacted the electrical firm that did the work - the electrician who did the job is being pulled off other work to 'come in for an interview', and a different electrician is coming out 'first thing' tomorrow to look at the issue.

I have double-checked, and the problem is still there - thankfully it is not a heisenbug.

The question on paperwork is interesting. I wasn't present when the work was done, and I was told I would get the necessary documentation later: of course, I got the bill, but I don't seem to have a copy of any testing documents. I will be very interested to see what the outcome is tomorrow.

The chap who did the work had some interesting working practices - I had to come back to the flat briefly while he was adding a new wall-mounted socket, and he was working alone, live - that is, he had not isolated the circuit he was working on. I was a tad surprised at this.

Many thanks for the advice, and the compliments on my diagnostics.

Regards,

Sid

On 03/03/14 16:05, wrote:
Just a quick update. I've left the original text as context,
apologies if I should have snipped some/all.

I have contacted the electrical firm that did the work - the
electrician who did the job is being pulled off other work to 'come
in for an interview', and a different electrician is coming out
'first thing' tomorrow to look at the issue.

OK - that sounds like the firm is taking this rather seriously. Good.

I have double-checked, and the problem is still there - thankfully it
is not a heisenbug.

The question on paperwork is interesting. I wasn't present when the
work was done, and I was told I would get the necessary documentation
later: of course, I got the bill, but I don't seem to have a copy of
any testing documents. I will be very interested to see what the
outcome is tomorrow.

The chap who did the work had some interesting working practices - I
had to come back to the flat briefly while he was adding a new
wall-mounted socket, and he was working alone, live - that is, he had
not isolated the circuit he was working on. I was a tad surprised at
this.

Then he's a steaming lunatic. This does not seem inconsistent with your
other problem.

If they find a problem, you should insist they perform a complete test
and inspection of the whole installation at their expense - who knows
what other corners had been cut?

Also that will generate you a fresh set of test documents (not
technically an EIC (installation certificate) but the numbers will be
the same.

On Mon, 03 Mar 2014 11:01:53 +0000, John Rumm wrote:

You should have received a test sheet, that among other things would
indicate the Earth Loop Impedance (ELI) of each circuit.

INAE but would the ELI test of each *circuit* pick up a disconnected
main earth to the CU or disconnection between the Main Earth Terminal
and the suppliers earth?

--
Cheers
Dave.

Tim Watts has brought this to us :
Then he's a steaming lunatic. This does not seem inconsistent with your other
problem.

I wouldn't put it quite that strongly, live working is not that unusual
and on even higher voltages. Often the only way faults can be found, is
with live working.

--
Regards,
Harry (M1BYT) (L)
http://www.ukradioamateur.co.uk

On 03/03/14 16:55, Harry Bloomfield wrote:
Tim Watts has brought this to us :
Then he's a steaming lunatic. This does not seem inconsistent with
your other problem.

I wouldn't put it quite that strongly, live working is not that unusual
and on even higher voltages. Often the only way faults can be found, is
with live working.


It is in domestic environments - especially when he's on his own - that
breaches pretty much all the H&S directives!

The main point is he's exposing himself and the customer (who was there
for that bit) to an unnecessary risk.

Harry Bloomfield wrote:
I wouldn't put it quite that strongly, live working is not that unusual
and on even higher voltages. Often the only way faults can be found, is
with live working.

Live *testing* is different from live *working*.

Although I was a bit reckless earlier, but leaving the circuit energised is the simplest way of finding out if I've breached the insulation ;-)

Owain

On 03/03/2014 00:21, pcb1962 wrote:
On 02/03/14 23:32, Tim Watts wrote:

That sounds like your main earth is missing - which is very very bad!

It's hard to be sure by a written account - but if I were you I would
call the electrician back asap. Or any electrician.

And until you do that stay out of the shower.




especially if playing electric guitar at the time

--
UK SelfBuild: http://uk.groups.yahoo.com/group/UK_Selfbuild/

On 03/03/2014 16:52, Dave Liquorice wrote:
On Mon, 03 Mar 2014 11:01:53 +0000, John Rumm wrote:

You should have received a test sheet, that among other things would
indicate the Earth Loop Impedance (ELI) of each circuit.

INAE but would the ELI test of each *circuit* pick up a disconnected
main earth to the CU or disconnection between the Main Earth Terminal
and the suppliers earth?

It ought to... with a disconnected earth (and what looks like main
bonding disconnected as well) the earth at each circuit is going to look
like its open circuit as well.


--
Cheers,

John.

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

On 03/03/2014 16:55, Harry Bloomfield wrote:
Tim Watts has brought this to us :
Then he's a steaming lunatic. This does not seem inconsistent with
your other problem.

I wouldn't put it quite that strongly, live working is not that unusual
and on even higher voltages. Often the only way faults can be found, is
with live working.

But domestic installation (as opposed to testing) work by someone who is
'at work' is illegal under the Electricity at Work regulations 1989,
regulation 14:

quote
Work on or near live conductors

14. No person shall be engaged in any work activity on or so near any
live conductor (other than one suitably covered with insulating material
so as to prevent danger) that danger may arise unless€“

(a)it is unreasonable in all the circumstances for it to be dead; and

(b)it is reasonable in all the circumstances for him to be at work on or
near it while it is live; and

(c)suitable precautions (including where necessary the provision of
suitable protective equipment) are taken to prevent injury.

/quote

What could make it unreasonable for a domestic final circuit to be made
dead in order to work on it?

--
Andy

On 03/03/2014 19:45, Andy Wade wrote:


What could make it unreasonable for a domestic final circuit to be made
dead in order to work on it?


Dunno. What sort of exception is envisaged by this bit of the reg? What
about, for example, if it were powering the customer's dialysis machine?
--
Cheers,
Roger
____________
Please reply to Newsgroup. Whilst email address is valid, it is seldom
checked.

On 03/03/2014 21:45, Roger Mills wrote:
On 03/03/2014 19:45, Andy Wade wrote:


What could make it unreasonable for a domestic final circuit to be made
dead in order to work on it?


Dunno. What sort of exception is envisaged by this bit of the reg? What
about, for example, if it were powering the customer's dialysis machine?

Just do it on a different day.

On 03/03/2014 21:45, Roger Mills wrote:
On 03/03/2014 19:45, Andy Wade wrote:

What could make it unreasonable for a domestic final circuit to be made
dead in order to work on it?

Dunno. What sort of exception is envisaged by this bit of the reg?

The utility DNO companies is the most common example; it would be
unreasonable to turn off whole streets to make a new service connection
or to change a house cut-out, for example. Conditions 14(b) and 14(c)
of the reg. are satisfied by the existence of established live-working
techniques, procedures, tools and training.

What about, for example, if it were powering the customer's dialysis
machine?

IMO no, how how would you satisfy 14(b)? You could work around that by
time scheduling, or providing an alternative supply from another circuit
or portable genny.

--
Andy

On Monday, March 3, 2014 4:05:59 PM UTC, wrote:
On Sunday, March 2, 2014 11:12:59 PM UTC, wrote:

Hi all,







I've recently had a consumer unit replaced in my flat, moving from cartridge fuses to RCBOs.







Following this, it looks like I may have an earth problem. While loading the dishwasher, I was leaning on the worktop with my hand on the stainless steel sink. On touching the inside of the diskwasher, I got a tingle.







So, I got out my multimeter and an extension cable and did some checks.







The potential difference between the inside of the dishwasher and the sink is approximately 55 to 60 VAC.







Checking the earth of the socket the d/w was plugged into, it too has a PD of about 55-60 VAC with the sink.







So I checked back to the heating radiators, and the PD between the electrical earth in the socket service the d/w and the radiators is alos approx 55-60 VAC.







Checked the same back to the main water incomer - also PD of 55-60 VAC.







Now, the d/w is on a separate way to other equipment in the kitchen, so I checked other kitchen sockets, and yes, you've guessed it, PD of about 55-60 VAC between electrical earth presented at the socket and the water pipes. And the same with stuff on yet another way in the consumer unit.







Is this normal for a an installation after RCBOs are installed? (I suspect not, but it would be nice to have this confirmed).







If not normal, what's the likely cause? Obviously, I'll need to get the professional electrician back who installed the new consumer unit, but I want to make sure I ask the right questions. Is it possible to simply forget to connect the protective earth through the consumer unit, so the 'downstream' side simply has a floating earth? So it could be a simple 'forgot to connect up a final wire'? That is, a could a missing single connection affect all ways?







As it is a block of flats, my consumer unit is in a set of cupboards next to each other in the common corridor outside the flats - one consumer unit per cupboard. The neighbours have not replaced their cartridge fuse consumer units, so still have an exposed earth terminal in their cupboards, and I was able to confirm that the all the metal cupboards (including mine) are connected to a protective earth which has zero PD with respect to the water pipes.







The RCBO protecting the d/w is a snazzy EATON one, which can give an indication of the leakage current it sees by flashing a multicoloured LED in a code in 'test mode'. On testing this, it gives a suspicious (to me) reading of 0 mA leakage; as does the RCBO covering the other kitchen equipment. To me, this seems to good to be true.







Comments and advice welcome, if if someone tells me I'm worrying over nothing.







Many thnaks,







Sid



Just a quick update. I've left the original text as context, apologies if I should have snipped some/all.



I have contacted the electrical firm that did the work - the electrician who did the job is being pulled off other work to 'come in for an interview', and a different electrician is coming out 'first thing' tomorrow to look at the issue.



I have double-checked, and the problem is still there - thankfully it is not a heisenbug.



The question on paperwork is interesting. I wasn't present when the work was done, and I was told I would get the necessary documentation later: of course, I got the bill, but I don't seem to have a copy of any testing documents. I will be very interested to see what the outcome is tomorrow.



The chap who did the work had some interesting working practices - I had to come back to the flat briefly while he was adding a new wall-mounted socket, and he was working alone, live - that is, he had not isolated the circuit he was working on. I was a tad surprised at this.



Many thanks for the advice, and the compliments on my diagnostics.



Regards,



Sid

Electrician been and gone. Turned out to be the same chap as did the installation first time round. He didn't even check the symptoms, but had the front of the consumer unit off two miutes after coming through the door, exposing the DIN rail the RCBOs were mounted on, and wired in a single earth cable from what I presume was a common or supplier earth point to somewhere. behind the RCBOs. I didn't get to see precisely.
Result of that was there is now negligiable potential difference between the water supply piping and sink and the electrical earth, both on the way the dishwasher is attached to and also for the electrical earths on the other 'ways'. I have checked.

He mumbled something about some installations needing additional earth connections, and was off. It was only afer he left I thought of test results.

Can't say I'm impressed - at least I'm not going to get a 'tingle' leaning on the edge of the sink while loading (or unloading) the dishwasher, so the problem is solved.

Thanks all for your advice. The main thing is that you confirmed to me that what I was experiencing was not normal, so I should get in contact with the electrical firm that did the work.

Regards,

Sid

wrote:

Electrician been and gone. Turned out to be the same chap as did the
installation first time round. He didn't even check the symptoms, but
had the front of the consumer unit off two miutes after coming
through the door, exposing the DIN rail the RCBOs were mounted on,
and wired in a single earth cable from what I presume was a common or
supplier earth point to somewhere. behind the RCBOs. I didn't get to
see precisely. Result of that was there is now negligiable potential
difference between the water supply piping and sink and the
electrical earth

I still wouldn't be impressed, get them to send a different sparky back
to do an inspection and report, make it clear if they don't arrange
that, you will and *THEY* will be paying for it ...

In article ,
writes

He mumbled something about some installations needing additional earth
connections, and was off. It was only afer he left I thought of test results.

Lying b'stard!

No admission of an error and no apology then.

Can't say I'm impressed - at least I'm not going to get a 'tingle' leaning on the edge
of the sink while loading (or unloading) the dishwasher, so the problem is solved.

I think you're right to be unimpressed.

Can you see the size of the earth wire he connected into the consumer
unit? It should be quite beefy as it provides the path for fault current
to trip breakers should a fault to earth develop.

My earth wire here is 10mm2 (the cross sectional area of the copper) and
that is just over 6mm in diameter, yours should be no less.

I'd be asking the firm for an inspection by a different electrician, at
their cost of course.
--
fred
it's a ba-na-na . . . .

In article , fred scribeth thus
In article ,
writes

He mumbled something about some installations needing additional earth
connections, and was off. It was only afer he left I thought of test results.

Lying b'stard!

No admission of an error and no apology then.

Can't say I'm impressed - at least I'm not going to get a 'tingle' leaning on
the edge
of the sink while loading (or unloading) the dishwasher, so the problem is
solved.

I think you're right to be unimpressed.

Can you see the size of the earth wire he connected into the consumer
unit? It should be quite beefy as it provides the path for fault current
to trip breakers should a fault to earth develop.

My earth wire here is 10mm2 (the cross sectional area of the copper) and
that is just over 6mm in diameter, yours should be no less.

I'd be asking the firm for an inspection by a different electrician, at
their cost of course.

Lets have a few pix posted up so we can see what's happened?...
--
Tony Sayer

tony sayer wrote:

Lets have a few pix posted up so we can see what's happened?...

If it's a block of flats, does the O/P necessarily have access to their
own meter cupboard?

wrote in message
...
Electrician been and gone. Turned out to be the same chap as did the
installation first time round. He didn't even check the symptoms, but had
the front of the consumer unit off two miutes after coming through the
door, exposing the DIN rail the RCBOs were mounted on, and wired in a
single earth cable from what I presume was a common or supplier earth
point to somewhere. behind the RCBOs.

I didn't get to see precisely.

So have a look and then you will know


--
Adam