I intend to replace my existing 8.5kW shower for a 9.5kW one. The
present one is wired in 6mm through a 40A mcb in the CU with a run of
about 7 metres with a double-pole isolator in the airing cupboard.

My intention is to replace the cable with 10mm through a 50A mcb, and to
replace the isolator with a separate shower CU (of this type, Wylex
NH204/63), again with a 50A mcb. Any thoughts/recommendations?

Joe Bloggs presented the following explanation :
I intend to replace my existing 8.5kW shower for a 9.5kW one. The present one
is wired in 6mm through a 40A mcb in the CU with a run of about 7 metres with
a double-pole isolator in the airing cupboard.

Assuming 240v - Your 40a and 6mm is just on the borderline for 9.5kW,
ignoring any volts drop.

Our 9.5Kw was originally an 8Kw shower wired in 6mm on a 40a MCB. It
has been fine for the past 10 years. Modern showers can modulate their
current needs as well as their flow.

Modern showers can modulate their
current needs as well as their flow.


But I bet most users need them on full all the time.

On 22-Jan-17 10:29 AM, Harry Bloomfield wrote:
Joe Bloggs presented the following explanation :
I intend to replace my existing 8.5kW shower for a 9.5kW one. The
present one is wired in 6mm through a 40A mcb in the CU with a run of
about 7 metres with a double-pole isolator in the airing cupboard.

Assuming 240v - Your 40a and 6mm is just on the borderline for 9.5kW,
ignoring any volts drop.

That's why I'm upgrading the supply cable and mcb.


Our 9.5Kw was originally an 8Kw shower wired in 6mm on a 40a MCB. It has
been fine for the past 10 years. Modern showers can modulate their
current needs as well as their flow.

What I was really unsure about was the necessity of the separate shower
CU. I intend to fit one, even though the shower would be fed from the
main CU which is RCD protected. But am I correct in thinking that the
shower needs a separate RCD?

On 22/01/2017 11:24, Joe Bloggs wrote:
On 22-Jan-17 10:29 AM, Harry Bloomfield wrote:
Joe Bloggs presented the following explanation :
I intend to replace my existing 8.5kW shower for a 9.5kW one. The
present one is wired in 6mm through a 40A mcb in the CU with a run of
about 7 metres with a double-pole isolator in the airing cupboard.

Assuming 240v - Your 40a and 6mm is just on the borderline for 9.5kW,
ignoring any volts drop.

That's why I'm upgrading the supply cable and mcb.


Our 9.5Kw was originally an 8Kw shower wired in 6mm on a 40a MCB. It has
been fine for the past 10 years. Modern showers can modulate their
current needs as well as their flow.

What I was really unsure about was the necessity of the separate shower
CU. I intend to fit one, even though the shower would be fed from the
main CU which is RCD protected. But am I correct in thinking that the
shower needs a separate RCD?


The shower does not need two lots of RCD protection.

--
Adam

On 22/01/2017 10:29, Harry Bloomfield wrote:
Joe Bloggs presented the following explanation :
I intend to replace my existing 8.5kW shower for a 9.5kW one. The
present one is wired in 6mm through a 40A mcb in the CU with a run of
about 7 metres with a double-pole isolator in the airing cupboard.

Assuming 240v - Your 40a and 6mm is just on the borderline for 9.5kW,
ignoring any volts drop.

I would not call it borderline.

--
Adam

Joe Bloggs formulated the question :
On 22-Jan-17 10:29 AM, Harry Bloomfield wrote:
Joe Bloggs presented the following explanation :
I intend to replace my existing 8.5kW shower for a 9.5kW one. The
present one is wired in 6mm through a 40A mcb in the CU with a run of
about 7 metres with a double-pole isolator in the airing cupboard.

Assuming 240v - Your 40a and 6mm is just on the borderline for 9.5kW,
ignoring any volts drop.

That's why I'm upgrading the supply cable and mcb.

Borderline, as in just adequate. Were it already installed I would
leave it as is, but would increase the capacity for a new install.



Our 9.5Kw was originally an 8Kw shower wired in 6mm on a 40a MCB. It has
been fine for the past 10 years. Modern showers can modulate their
current needs as well as their flow.

What I was really unsure about was the necessity of the separate shower CU. I
intend to fit one, even though the shower would be fed from the main CU which
is RCD protected. But am I correct in thinking that the shower needs a
separate RCD?

No point in adding a second RCD of the same trip rating, there would be
no discrimination - so either or both could trip. They don't need a
separate CU, just a local means of isolation. Either a pull switch or
an isolator outside the door, with an indicator.

ARW expressed precisely :
I would not call it borderline.

Just comfortably adequate then?

After serious thinking Harry Bloomfield wrote :
ARW expressed precisely :
I would not call it borderline.

Just comfortably adequate then?

The OP seems to have his mind set on replacing it with a higher rated
cable.

On Sunday, 22 January 2017 14:27:43 UTC, Harry Bloomfield wrote:
After serious thinking Harry Bloomfield wrote :
ARW expressed precisely :
I would not call it borderline.

Just comfortably adequate then?

The OP seems to have his mind set on replacing it with a higher rated
cable.

How many sq mm do you get in a pair of 22mm water pipes?


NT

On Sunday, 22 January 2017 09:55:59 UTC, Joe Bloggs wrote:
I intend to replace my existing 8.5kW shower for a 9.5kW one.
Any thoughts/recommendations?

Go for a 10.5 kW one. It's the difference between an 11% and a 23% better shower.

You're upgrading the cable etc anyway.

Owain

Harry Bloomfield explained on 22/01/2017 :
ARW expressed precisely :
I would not call it borderline.

Just comfortably adequate then?

47amps if installed clipped direct to a wall, or embedded in none
insulating materials. 34amps if installed in insulation materials.
Likely the OP had in mind some installation method in between?

240v 9.5Kw = 39.58 amps.

On 22/01/2017 09:55, Joe Bloggs wrote:

I intend to replace my existing 8.5kW shower for a 9.5kW one. The
present one is wired in 6mm through a 40A mcb in the CU with a run of
about 7 metres with a double-pole isolator in the airing cupboard.

ok

You have not mentioned a RCD... is there one on the current circuit?

(if just changing the shower and leaving the rest alone, and the
existing installation is meets the required disconnect times - then you
could argue there is no requirement to do a full 17th edition style upgrade)

My intention is to replace the cable with 10mm through a 50A mcb, and to

The "clipped direct" installed capacity of 6mm^2 is 47A. Your load of
9k5W will probably be specified at 240V, so you nominal current will be
39A. So in loading terms you would be fine and nothing is going to
overheat etc.

Voltage drop is fine at under 2V

Chances are the loop impedance that that length is in spec (even with
the new 17th edition amendment 3 reductions is max Zs)

The adiabatic check suggests a minimum protective conductor size on 40A
MCB of s = sqrt( 400^2 x 0.1 ) / 115 = ~1 mm^2 which is also fine.

replace the isolator with a separate shower CU (of this type, Wylex
NH204/63), again with a 50A mcb. Any thoughts/recommendations?

If you don't already have a RCD on the shower, then you could use an
enclosure like that to add one. However you may just be able to use B40
RCBO in the current CU (and keep the existing isolator).


--
Cheers,

John.

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

On 22/01/2017 11:24, Joe Bloggs wrote:
On 22-Jan-17 10:29 AM, Harry Bloomfield wrote:
Joe Bloggs presented the following explanation :
I intend to replace my existing 8.5kW shower for a 9.5kW one. The
present one is wired in 6mm through a 40A mcb in the CU with a run of
about 7 metres with a double-pole isolator in the airing cupboard.

Assuming 240v - Your 40a and 6mm is just on the borderline for 9.5kW,
ignoring any volts drop.

That's why I'm upgrading the supply cable and mcb.


Our 9.5Kw was originally an 8Kw shower wired in 6mm on a 40a MCB. It has
been fine for the past 10 years. Modern showers can modulate their
current needs as well as their flow.

What I was really unsure about was the necessity of the separate shower
CU. I intend to fit one, even though the shower would be fed from the
main CU which is RCD protected. But am I correct in thinking that the
shower needs a separate RCD?

No.

New 17th edition installs would need RCD protection at a maximum trip
threshold of 30mA. There is no requirement for that to be an additional
or dedicated RCD.

--
Cheers,

John.

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

On 22/01/2017 14:25, Harry Bloomfield wrote:
Joe Bloggs formulated the question :
On 22-Jan-17 10:29 AM, Harry Bloomfield wrote:
Joe Bloggs presented the following explanation :
I intend to replace my existing 8.5kW shower for a 9.5kW one. The
present one is wired in 6mm through a 40A mcb in the CU with a run of
about 7 metres with a double-pole isolator in the airing cupboard.

Assuming 240v - Your 40a and 6mm is just on the borderline for 9.5kW,
ignoring any volts drop.

That's why I'm upgrading the supply cable and mcb.

Borderline, as in just adequate.

If the install is as the OP describes, then its adequate - and that is
all that counts really - since it will not exceed any technical parameter.

Were it already installed I would leave
it as is, but would increase the capacity for a new install.

With that I would concur... No point going to all that hassle and
fitting a 9.5kW shower. If doing a new install it would obviously be
worth going for a higher spec to allow for a more powerful shower.

If the OP is set on cable upgrades etc, then he may as well go for a
better shower as well.



--
Cheers,

John.

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

On 22/01/2017 14:45, wrote:
On Sunday, 22 January 2017 14:27:43 UTC, Harry Bloomfield wrote:
After serious thinking Harry Bloomfield wrote :
ARW expressed precisely :
I would not call it borderline.

Just comfortably adequate then?

The OP seems to have his mind set on replacing it with a higher rated
cable.

How many sq mm do you get in a pair of 22mm water pipes?

You mean in terms of CSA of copper? Over 27mm^2 per pipe if my sums are
right... (assuming a 0.8mm wall thickness)


--
Cheers,

John.

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

On 22/01/2017 14:45, wrote:
On Sunday, 22 January 2017 09:55:59 UTC, Joe Bloggs wrote:
I intend to replace my existing 8.5kW shower for a 9.5kW one.
Any thoughts/recommendations?

Go for a 10.5 kW one. It's the difference between an 11% and a 23% better shower.

You're upgrading the cable etc anyway.

Yup, if going to the hassle of putting in a bigger cable, you may as
well get some benefit from it!


--
Cheers,

John.

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

On 22-Jan-17 3:11 PM, John Rumm wrote:
On 22/01/2017 09:55, Joe Bloggs wrote:

I intend to replace my existing 8.5kW shower for a 9.5kW one. The
present one is wired in 6mm through a 40A mcb in the CU with a run of
about 7 metres with a double-pole isolator in the airing cupboard.

ok

You have not mentioned a RCD... is there one on the current circuit?

(if just changing the shower and leaving the rest alone, and the
existing installation is meets the required disconnect times - then you
could argue there is no requirement to do a full 17th edition style
upgrade)

My intention is to replace the cable with 10mm through a 50A mcb, and to

The "clipped direct" installed capacity of 6mm^2 is 47A. Your load of
9k5W will probably be specified at 240V, so you nominal current will be
39A. So in loading terms you would be fine and nothing is going to
overheat etc.

Voltage drop is fine at under 2V

Chances are the loop impedance that that length is in spec (even with
the new 17th edition amendment 3 reductions is max Zs)

The adiabatic check suggests a minimum protective conductor size on 40A
MCB of s = sqrt( 400^2 x 0.1 ) / 115 = ~1 mm^2 which is also fine.

replace the isolator with a separate shower CU (of this type, Wylex
NH204/63), again with a 50A mcb. Any thoughts/recommendations?

If you don't already have a RCD on the shower, then you could use an
enclosure like that to add one. However you may just be able to use B40
RCBO in the current CU (and keep the existing isolator).




Thanks for all the, very helpful, replies. To clarify things I'll do a
block response to some of the queries raised.

I have already run a length of 10mm from the CU to the airing cupboard
(not yet connected) so there's no question of sticking with the existing
cable. There is a 30mA RCD in the existing CU, so it sounds like that's
all that's required. As stated, the cable run is about 7 metres and runs
from the CU up into the loft (this is a bungalow) and across and down to
the airing cupboard. I will run it under the loft insulation (not
clipped to anything) - or over it if this is likely to be a problem.

I think I'll just upgrade the existing double pole switch in the airing
cupboard - the current one doesn't have a neon indicator - and dispense
with the idea of a separate shower CU. The existing shower is fed
through a 32A mcb, which I will upgrade to 50A. The suggestion of a
10.5kW shower seems a good one, which I will look into - although I was
under the impression that this might run close to a requirement for 16mm
cable.

I should add that the property has TT earthing.

Any additional advice/comments would be very welcome.

Joe Bloggs wrote :
I think I'll just upgrade the existing double pole switch in the airing
cupboard - the current one doesn't have a neon indicator - and dispense with
the idea of a separate shower CU. The existing shower is fed through a 32A
mcb, which I will upgrade to 50A. The suggestion of a 10.5kW shower seems a
good one, which I will look into - although I was under the impression that
this might run close to a requirement for 16mm cable.

Dependent upon the installation conditions of your present 6mm T&E, it
might be able to support even the 10.5kW shower at 43.75amps full
load(10500w/240v = 43.75amps). Your 10mm is definitely more than
adequate for the purpose, absolutely no need for 16mm and you might
find it a struggle/impossible to get into the terminals.

6mm unless covered by insulation is rated at 47amps.

Avoiding running cables under or through insulation is always a good
idea, especially those which carry heavier currents.

Your 30mA RCD covers what you need, but if it provides cover for ALL of
the circuits, you might find it better to replace that with a 100mA and
fit a separate 30mA RCDBO for just the shower circuit - it avoids all
your circuits tripping out, due to a fault on one circuit.

On 22/01/2017 14:45, wrote:
On Sunday, 22 January 2017 09:55:59 UTC, Joe Bloggs wrote:
I intend to replace my existing 8.5kW shower for a 9.5kW one.
Any thoughts/recommendations?

Go for a 10.5 kW one. It's the difference between an 11% and a 23% better shower.

You're upgrading the cable etc anyway.

Just run the 6mm t&E next to the showers water pipe for extra performance.


--
Adam

It happens that ARW formulated :
Just run the 6mm t&E next to the showers water pipe for extra performance.

Or use oxygen free copper pipe Þ

On 22/01/2017 14:51, Harry Bloomfield wrote:
Harry Bloomfield explained on 22/01/2017 :
ARW expressed precisely :
I would not call it borderline.

Just comfortably adequate then?

47amps if installed clipped direct to a wall, or embedded in none
insulating materials. 34amps if installed in insulation materials.
Likely the OP had in mind some installation method in between?

240v 9.5Kw = 39.58 amps.

****ing hell. Is this the Spanish inquisition?

--
Adam

On 22-Jan-17 6:13 PM, Harry Bloomfield wrote:
Joe Bloggs wrote :
I think I'll just upgrade the existing double pole switch in the
airing cupboard - the current one doesn't have a neon indicator - and
dispense with the idea of a separate shower CU. The existing shower is
fed through a 32A mcb, which I will upgrade to 50A. The suggestion of
a 10.5kW shower seems a good one, which I will look into - although I
was under the impression that this might run close to a requirement
for 16mm cable.

Dependent upon the installation conditions of your present 6mm T&E, it
might be able to support even the 10.5kW shower at 43.75amps full
load(10500w/240v = 43.75amps). Your 10mm is definitely more than
adequate for the purpose, absolutely no need for 16mm and you might find
it a struggle/impossible to get into the terminals.

6mm unless covered by insulation is rated at 47amps.

Avoiding running cables under or through insulation is always a good
idea, especially those which carry heavier currents.

Your 30mA RCD covers what you need, but if it provides cover for ALL of
the circuits, you might find it better to replace that with a 100mA and
fit a separate 30mA RCDBO for just the shower circuit - it avoids all
your circuits tripping out, due to a fault on one circuit.


Thanks again for that. What about running the shower through a 50A 30mA
RCBO fitted on the non-RCD side of my CU?

On 22/01/2017 18:13, Harry Bloomfield wrote:
Joe Bloggs wrote :
I think I'll just upgrade the existing double pole switch in the
airing cupboard - the current one doesn't have a neon indicator - and
dispense with the idea of a separate shower CU. The existing shower is
fed through a 32A mcb, which I will upgrade to 50A. The suggestion of
a 10.5kW shower seems a good one, which I will look into - although I
was under the impression that this might run close to a requirement
for 16mm cable.

Dependent upon the installation conditions of your present 6mm T&E, it
might be able to support even the 10.5kW shower at 43.75amps full
load(10500w/240v = 43.75amps). Your 10mm is definitely more than
adequate for the purpose, absolutely no need for 16mm and you might find
it a struggle/impossible to get into the terminals.

6mm unless covered by insulation is rated at 47amps.

Avoiding running cables under or through insulation is always a good
idea, especially those which carry heavier currents.

I agree.


--
Adam

On 22/01/2017 19:21, Joe Bloggs wrote:


Thanks again for that. What about running the shower through a 50A 30mA
RCBO fitted on the non-RCD side of my CU?

Then get a pro in. A TT supply should not have a non RCD side.

--
Adam

On 22/01/2017 16:24, Joe Bloggs wrote:

Thanks for all the, very helpful, replies. To clarify things I'll do a
block response to some of the queries raised.

I have already run a length of 10mm from the CU to the airing cupboard
(not yet connected) so there's no question of sticking with the existing
cable. There is a 30mA RCD in the existing CU, so it sounds like that's
all that's required. As stated, the cable run is about 7 metres and runs
from the CU up into the loft (this is a bungalow) and across and down to
the airing cupboard. I will run it under the loft insulation (not
clipped to anything) - or over it if this is likely to be a problem.

Under the insulation you *must not* do in this circumstance - even with
10mm^2 cable. Assuming you have 100mm or more of insulation that would
mean you are using installation method 101 which would drop the
tabulated current carrying capacity of the cable to 36A (and that is if
it remains in contact with the plasterboard below - its even lower if
surrounded by insulation). See the table he

http://wiki.diyfaq.org.uk/index.php/Cables#Cable_Sizes

also look at the insulation methods he

http://wiki.diyfaq.org.uk/index.php/...lation_Methods

(note there are many more scenarios described in BS7671, but the ones
listed there are the most commonly applicable to domestic wiring).

So above the insulation is vastly preferable. (and leave a bit of space
round it where it goes through the insulation on the way up and down)

Note also that if the airing cupboard is normally above 30 degrees, then
you may also need to allow for some de-rating due to ambient
temperature. See the table 4B1 he

http://wiki.diyfaq.org.uk/index.php/...you r_circuit


I think I'll just upgrade the existing double pole switch in the airing
cupboard - the current one doesn't have a neon indicator - and dispense
with the idea of a separate shower CU. The existing shower is fed
through a 32A mcb, which I will upgrade to 50A. The suggestion of a
10.5kW shower seems a good one, which I will look into - although I was
under the impression that this might run close to a requirement for 16mm
cable.

So long as you don't complicate it with running cables in insulation
then the 10mm^2 cable is good for up to 64A, which will be more than
adequate by a long way. (in reality, even the 6mm^2 cable would be ok on
a 10.5kW shower)

I should add that the property has TT earthing.

Not going to make much difference in this particular case...

Any additional advice/comments would be very welcome.

I take it your incoming main fuse is rated at 60A or better? (otherwise
a more powerful shower may push you close to the limit with other
household loads).



--
Cheers,

John.

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

On 22-Jan-17 7:23 PM, ARW wrote:
On 22/01/2017 19:21, Joe Bloggs wrote:


Thanks again for that. What about running the shower through a 50A 30mA
RCBO fitted on the non-RCD side of my CU?

Then get a pro in. A TT supply should not have a non RCD side.


There is nothing connected to the non-RCD side of the CU. But what would
be wrong with taking the shower supply from it through a 30mA RCBO?

On 22-Jan-17 7:31 PM, John Rumm wrote:
On 22/01/2017 16:24, Joe Bloggs wrote:

Thanks for all the, very helpful, replies. To clarify things I'll do a
block response to some of the queries raised.

I have already run a length of 10mm from the CU to the airing cupboard
(not yet connected) so there's no question of sticking with the existing
cable. There is a 30mA RCD in the existing CU, so it sounds like that's
all that's required. As stated, the cable run is about 7 metres and runs
from the CU up into the loft (this is a bungalow) and across and down to
the airing cupboard. I will run it under the loft insulation (not
clipped to anything) - or over it if this is likely to be a problem.

Under the insulation you *must not* do in this circumstance - even with
10mm^2 cable. Assuming you have 100mm or more of insulation that would
mean you are using installation method 101 which would drop the
tabulated current carrying capacity of the cable to 36A (and that is if
it remains in contact with the plasterboard below - its even lower if
surrounded by insulation). See the table he

http://wiki.diyfaq.org.uk/index.php/Cables#Cable_Sizes

also look at the insulation methods he

http://wiki.diyfaq.org.uk/index.php/...lation_Methods

(note there are many more scenarios described in BS7671, but the ones
listed there are the most commonly applicable to domestic wiring).

So above the insulation is vastly preferable. (and leave a bit of space
round it where it goes through the insulation on the way up and down)

Note also that if the airing cupboard is normally above 30 degrees, then
you may also need to allow for some de-rating due to ambient
temperature. See the table 4B1 he

http://wiki.diyfaq.org.uk/index.php/...you r_circuit



I think I'll just upgrade the existing double pole switch in the airing
cupboard - the current one doesn't have a neon indicator - and dispense
with the idea of a separate shower CU. The existing shower is fed
through a 32A mcb, which I will upgrade to 50A. The suggestion of a
10.5kW shower seems a good one, which I will look into - although I was
under the impression that this might run close to a requirement for 16mm
cable.

So long as you don't complicate it with running cables in insulation
then the 10mm^2 cable is good for up to 64A, which will be more than
adequate by a long way. (in reality, even the 6mm^2 cable would be ok on
a 10.5kW shower)

Ok, thanks. I certainly won't run it under the insulation then.



I should add that the property has TT earthing.

Not going to make much difference in this particular case...

Any additional advice/comments would be very welcome.

I take it your incoming main fuse is rated at 60A or better? (otherwise
a more powerful shower may push you close to the limit with other
household loads).


The incoming fuse is 80A.

On 22/01/2017 14:45, wrote:
On Sunday, 22 January 2017 09:55:59 UTC, Joe Bloggs wrote:
I intend to replace my existing 8.5kW shower for a 9.5kW one.
Any thoughts/recommendations?

Go for a 10.5 kW one. It's the difference between an 11% and a 23% better shower.

You're upgrading the cable etc anyway.

Owain




Electric Showers taken a big leap in power since I last installed one.
Think it was around 6 or 6.5kW

rick brought next idea :
Electric Showers taken a big leap in power since I last installed one.
Think it was around 6 or 6.5kW

They have changed in capability too. The original showers were only
really usable in summer and you had to adjust the flow, to set the
temperature.

Modern ones are usable in winter and the control system is much more
clever. On mine you just set the temperature you desire and it
modulates the water flow and current to achieve that.

On Sunday, 22 January 2017 15:24:25 UTC, John Rumm wrote:
On 22/01/2017 14:45, tabbypurr wrote:
On Sunday, 22 January 2017 14:27:43 UTC, Harry Bloomfield wrote:
After serious thinking Harry Bloomfield wrote :
ARW expressed precisely :

The OP seems to have his mind set on replacing it with a higher rated
cable.

How many sq mm do you get in a pair of 22mm water pipes?

You mean in terms of CSA of copper? Over 27mm^2 per pipe if my sums are
right... (assuming a 0.8mm wall thickness)

should support the full 100A if you run the pipes through the CU 24kW.


NT

On 22/01/2017 19:55, Joe Bloggs wrote:
On 22-Jan-17 7:23 PM, ARW wrote:
On 22/01/2017 19:21, Joe Bloggs wrote:


Thanks again for that. What about running the shower through a 50A 30mA
RCBO fitted on the non-RCD side of my CU?

Then get a pro in. A TT supply should not have a non RCD side.


There is nothing connected to the non-RCD side of the CU. But what would
be wrong with taking the shower supply from it through a 30mA RCBO?

That's fine...

As you are probably aware, all circuits must have RCD protection on a TT
install. Typically this was done with a 100mA time delayed RCD on the
incoming side of a traditional split load CU to protect "everything",
and then other 30mA RCDs would protect circuits where "direct contact"
protection (or "basic protection" as its now called) was required.

A traditional split load with shared RCDs on one side, and then all
RCBOs on the other is also fine for TT. (all RCBOs being the "nicest"
option).


--
Cheers,

John.

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

On 22-Jan-17 7:23 PM, ARW wrote:
On 22/01/2017 19:21, Joe Bloggs wrote:


Thanks again for that. What about running the shower through a 50A 30mA
RCBO fitted on the non-RCD side of my CU?

Then get a pro in. A TT supply should not have a non RCD side.


I am a 'pro', and I was a 'pro' when you were in short trousers, but I
am not an electrician.

My world was machine control, telecommunications and electronics, and my
qualifications in that area of the electrical world are a great deal
higher than most electricians. But domestic electrics are not my thing,
and therefore I am not completely au fait with all the regulations that
apply. That's why I generally seek advice from those that are before I
do anything, and I am very grateful to those here who have been generous
with their help and advice. Advice which I shall be careful to take heed of.

I can assure you, that I am no fool, and if I come over that way it is
largely because I don't believe in pretending to know things that I
clearly don't. The electrical world is vast, and contains many
specialities and disciplines, a world where it is possible to be an
expert in some aspects and know very little about others. It is also
one, like most others, that the more you know the more you realise how
little you know. Clearly you haven't got there yet.

On 22/01/2017 19:55, Joe Bloggs wrote:
On 22-Jan-17 7:23 PM, ARW wrote:
On 22/01/2017 19:21, Joe Bloggs wrote:


Thanks again for that. What about running the shower through a 50A 30mA
RCBO fitted on the non-RCD side of my CU?

Then get a pro in. A TT supply should not have a non RCD side.


There is nothing connected to the non-RCD side of the CU. But what would
be wrong with taking the shower supply from it through a 30mA RCBO?

Nothing, I was looking at your 50A MCB post:-(

--
Adam

Harry Bloomfield Wrote in message:
It happens that ARW formulated :
Just run the 6mm t&E next to the showers water pipe for extra performance.

Or use oxygen free copper pipe Þ


Russ Andrews?
--
Jim K


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