Victorian house converted into flats 20 years ago, communal areas have
chandeliers each having 11 x 25w incandescent candle lamps, controlled
by electronic time lag switches.

First floor has 2 x chandeliers, ground floor has 3.

First floor has a 6 amp MCB, ground floor has a 10 amp.

The first floor MCB has tripped recently (once to my knowledge).
Landlord has asked me to arrange for the 6 amp MCB to be changed to a 10
amp MCB.

IANAE but my gut feeling is that this would be 'wrong'.

The size of the MCBs was obviously chosen for a good reason. I've tried
explaining this to the landlord, but I'm not getting through.

Any comments?



--
Dave - The Medway Handyman www.medwayhandyman.co.uk

On Tue, 25 Feb 2014 08:17:51 +0000, The Medway Handyman wrote:

Victorian house converted into flats 20 years ago, communal areas have
chandeliers each having 11 x 25w incandescent candle lamps, controlled
by electronic time lag switches.

First floor has 2 x chandeliers, ground floor has 3.

First floor has a 6 amp MCB, ground floor has a 10 amp.

11 * 25 * 2 = 550 W = 2.4 A @ 230 V
11 * 25 * 3 = 825 W = 3.6 A @ 230 V

So a 6A MCB ought to be ample for either, unless there are other
loads not metioned on those MCBs.

With 55 tungsten lamps at 2,000 hrs life each that's one going pop
every 36 hrs of use... I guess with 11 in each chandelier untill
three or four have gone it doesn't notice but all the same, that
number of bulbs and 1.4 kW of power when all on, they must have money
to burn...

The first floor MCB has tripped recently (once to my knowledge).

Did a bulb blow at the same time?

IANAE but my gut feeling is that this would be 'wrong'.

To do blindly yes, you really need to know the size of the cable used
to wire the fittings and how it's installed. IANAE either and don't
have the figures off the top of my head. 6 to 10 A might be OK but if
it's tripping due to in rush at switch on rather than a bulb blowing
then a 6 A type C would be better.

--
Cheers
Dave.

On 25/02/2014 08:17, The Medway Handyman wrote:
Victorian house converted into flats 20 years ago, communal areas have
chandeliers each having 11 x 25w incandescent candle lamps, controlled
by electronic time lag switches.

First floor has 2 x chandeliers, ground floor has 3.

First floor has a 6 amp MCB, ground floor has a 10 amp.

The first floor MCB has tripped recently (once to my knowledge).
Landlord has asked me to arrange for the 6 amp MCB to be changed to a 10
amp MCB.

IANAE but my gut feeling is that this would be 'wrong'.

That would depend... to just swap without knowing details of the circuit
certainly would be.

Also if (as I suspect) he is just trying to lower the chances of a
nuisance trip on a bulb failure, a better way to do it would be to
change the type of MCB from a B to a C. While having the same thermal
response curve, a A 6A type C will need a higher fault current of 60A to
trip "instantly" (compared with the normal of 30A). A 10A type B will
only need 50A to trip instantly for comparison.

The size of the MCBs was obviously chosen for a good reason. I've tried
explaining this to the landlord, but I'm not getting through.

Any comments?

There are three "standard" lighting circuit protective device sizes, 6,
10, & 16A. The latter usually only seen in commercial applications
(office full of strip lights for example).

Here is the list:

http://wiki.diyfaq.org.uk/images/2/2...g-Circuits.jpg

There are implications of say swapping from a 6 to a 10

Say the circuit was wired in 1.0mm T&E, its TN-S and not RCD protected.
Your maximum circuit length with a 6A device is 59m in most cases. The
same circuit with a 10A MCB, would have a maximum length of on 35m. So
to safely swap from one to the other, you need to know the maximum cable
length from CU to furthest light fitting on the circuit. (if wired in
1.5mm T&E the corresponding figures would be 90 and 52m)

Generally going from a B to a C device is a much safer gambit. On a
1.0mm T&E circuit there are no typical trade offs. On a 1.5mm T&E
circuit there is a small max length reduction on TN-S installs (90 to
83m due to earth loop impedance getting too large)



--
Cheers,

John.

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

On 25/02/2014 08:45, Dave Liquorice wrote:
On Tue, 25 Feb 2014 08:17:51 +0000, The Medway Handyman wrote:

Victorian house converted into flats 20 years ago, communal areas have
chandeliers each having 11 x 25w incandescent candle lamps, controlled
by electronic time lag switches.

First floor has 2 x chandeliers, ground floor has 3.

First floor has a 6 amp MCB, ground floor has a 10 amp.

11 * 25 * 2 = 550 W = 2.4 A @ 230 V
11 * 25 * 3 = 825 W = 3.6 A @ 230 V

So a 6A MCB ought to be ample for either, unless there are other
loads not metioned on those MCBs.

With 55 tungsten lamps at 2,000 hrs life each that's one going pop
every 36 hrs of use...

On average - which means nothing if you change all the bulbs at the same
time. Lamps are usually pretty consistent in life IME.

To do blindly yes, you really need to know the size of the cable used
to wire the fittings and how it's installed. IANAE either and don't
have the figures off the top of my head. 6 to 10 A might be OK but if
it's tripping due to in rush at switch on rather than a bulb blowing
then a 6 A type C would be better.

Indeed - it will also help on bulb failure. Some bulb types are worse
than others IME. Small golf ball types and GU10 mains halogens being
more likely to cause a trip on failure compared to normal GLS. Candle
lamps seem somewhere in the middle.

Odd the landlord does not change them to LE lamps - but it might be that
the switches depend on some let through current to power the switch.
Perhaps suggesting PIR control of them instead would make more sense. Or
use vacuum switches.


--
Cheers,

John.

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

In article ,
John Rumm writes:
On 25/02/2014 08:17, The Medway Handyman wrote:
Victorian house converted into flats 20 years ago, communal areas have
chandeliers each having 11 x 25w incandescent candle lamps, controlled
by electronic time lag switches.

First floor has 2 x chandeliers, ground floor has 3.

First floor has a 6 amp MCB, ground floor has a 10 amp.

The first floor MCB has tripped recently (once to my knowledge).
Landlord has asked me to arrange for the 6 amp MCB to be changed to a 10
amp MCB.

IANAE but my gut feeling is that this would be 'wrong'.

That would depend... to just swap without knowing details of the circuit
certainly would be.

Also if (as I suspect) he is just trying to lower the chances of a
nuisance trip on a bulb failure, a better way to do it would be to
change the type of MCB from a B to a C. While having the same thermal
response curve, a A 6A type C will need a higher fault current of 60A to
trip "instantly" (compared with the normal of 30A). A 10A type B will
only need 50A to trip instantly for comparison.

The size of the MCBs was obviously chosen for a good reason. I've tried
explaining this to the landlord, but I'm not getting through.

Any comments?

There are three "standard" lighting circuit protective device sizes, 6,
10, & 16A. The latter usually only seen in commercial applications
(office full of strip lights for example).

Here is the list:

http://wiki.diyfaq.org.uk/images/2/2...g-Circuits.jpg

There are implications of say swapping from a 6 to a 10

Say the circuit was wired in 1.0mm T&E, its TN-S and not RCD protected.
Your maximum circuit length with a 6A device is 59m in most cases. The
same circuit with a 10A MCB, would have a maximum length of on 35m. So
to safely swap from one to the other, you need to know the maximum cable
length from CU to furthest light fitting on the circuit. (if wired in
1.5mm T&E the corresponding figures would be 90 and 52m)

Generally going from a B to a C device is a much safer gambit. On a
1.0mm T&E circuit there are no typical trade offs. On a 1.5mm T&E
circuit there is a small max length reduction on TN-S installs (90 to
83m due to earth loop impedance getting too large)

Another factor is the lampholders.
SES and SBC allow 6A max circuit protection.
BC and SES are higher (I can't recall exactly what, without the regs).

Change the lamps to LEDs.
If necessary, change the control switch to one which will work with them,
although the power reduction may be so much that it's still cheaper even
if they're left on (particularly if they add in your relamping and call-
out charges).

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

It won't make any difference if its the blown bulb syndrome blowing it I'd
imagine, which makes me wonder they the other 10A ones do not blow as well,
its suspicious.
Brian

--
From the Sofa of Brian Gaff Reply address is active
"The Medway Handyman" wrote in message
...
Victorian house converted into flats 20 years ago, communal areas have
chandeliers each having 11 x 25w incandescent candle lamps, controlled by
electronic time lag switches.

First floor has 2 x chandeliers, ground floor has 3.

First floor has a 6 amp MCB, ground floor has a 10 amp.

The first floor MCB has tripped recently (once to my knowledge). Landlord
has asked me to arrange for the 6 amp MCB to be changed to a 10 amp MCB.

IANAE but my gut feeling is that this would be 'wrong'.

The size of the MCBs was obviously chosen for a good reason. I've tried
explaining this to the landlord, but I'm not getting through.

Any comments?



--
Dave - The Medway Handyman www.medwayhandyman.co.uk

On 25/02/2014 09:40, Andrew Gabriel wrote:
In article ,
John Rumm writes:
On 25/02/2014 08:17, The Medway Handyman wrote:
Victorian house converted into flats 20 years ago, communal areas have
chandeliers each having 11 x 25w incandescent candle lamps, controlled
by electronic time lag switches.

First floor has 2 x chandeliers, ground floor has 3.

First floor has a 6 amp MCB, ground floor has a 10 amp.

The first floor MCB has tripped recently (once to my knowledge).
Landlord has asked me to arrange for the 6 amp MCB to be changed to a 10
amp MCB.

IANAE but my gut feeling is that this would be 'wrong'.

That would depend... to just swap without knowing details of the circuit
certainly would be.

Also if (as I suspect) he is just trying to lower the chances of a
nuisance trip on a bulb failure, a better way to do it would be to
change the type of MCB from a B to a C. While having the same thermal
response curve, a A 6A type C will need a higher fault current of 60A to
trip "instantly" (compared with the normal of 30A). A 10A type B will
only need 50A to trip instantly for comparison.

The size of the MCBs was obviously chosen for a good reason. I've tried
explaining this to the landlord, but I'm not getting through.

Any comments?

There are three "standard" lighting circuit protective device sizes, 6,
10, & 16A. The latter usually only seen in commercial applications
(office full of strip lights for example).

Here is the list:

http://wiki.diyfaq.org.uk/images/2/2...g-Circuits.jpg

There are implications of say swapping from a 6 to a 10

Say the circuit was wired in 1.0mm T&E, its TN-S and not RCD protected.
Your maximum circuit length with a 6A device is 59m in most cases. The
same circuit with a 10A MCB, would have a maximum length of on 35m. So
to safely swap from one to the other, you need to know the maximum cable
length from CU to furthest light fitting on the circuit. (if wired in
1.5mm T&E the corresponding figures would be 90 and 52m)

Generally going from a B to a C device is a much safer gambit. On a
1.0mm T&E circuit there are no typical trade offs. On a 1.5mm T&E
circuit there is a small max length reduction on TN-S installs (90 to
83m due to earth loop impedance getting too large)

Another factor is the lampholders.
SES and SBC allow 6A max circuit protection.

That used to be the case, but ISTR they removed the restriction on using
the small lamp holders with 10A circuits in the 17th edition...

BC and SES are higher (I can't recall exactly what, without the regs).

Change the lamps to LEDs.
If necessary, change the control switch to one which will work with them,
although the power reduction may be so much that it's still cheaper even
if they're left on (particularly if they add in your relamping and call-
out charges).


Yup...


--
Cheers,

John.

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

On 25/02/2014 12:15, Brian Gaff wrote:
It won't make any difference if its the blown bulb syndrome blowing it I'd
imagine, which makes me wonder they the other 10A ones do not blow as well,
its suspicious.

The 10A one will take a higher fault current to trip... so depending on
how hard the "short" the lamp presents on failure, you may see a
discrepancy in performance.


--
Cheers,

John.

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