I have mentioned before that we live in a house with an ex shop
attached, and both have separate electricity supplies, the ex shop using
roughly 1500 units per annum, with a daily charge of 25p per day or
91.25 pa, plus VAT.

Ignoring usage figures, I am thinking I could save the daily charge by
having the shop supply come from the house rather than a separate
supply, and save £95 pa. However, that does not include the cost of
the wiring, which I would not attempt myself. It seems, though, that I
would have to live, and live here, for a good few years before the
annual saving exceeded the initial cost. How long is a piece of string?
How many years? Ten? Twenty? More?
--
Graeme

On 25/06/2017 08:05, Graeme wrote:

I have mentioned before that we live in a house with an ex shop
attached, and both have separate electricity supplies, the ex shop using
roughly 1500 units per annum, with a daily charge of 25p per day or
91.25 pa, plus VAT.

Ignoring usage figures, I am thinking I could save the daily charge by
having the shop supply come from the house rather than a separate
supply, and save £95 pa. However, that does not include the cost of
the wiring, which I would not attempt myself. It seems, though, that I
would have to live, and live here, for a good few years before the
annual saving exceeded the initial cost. How long is a piece of string?
How many years? Ten? Twenty? More?


As the annual cost is made of a daily charge and a unit charge the
saving may be more than £95. With the combined meter you save £95 if
nothing else changes but you may find a another supplier has a higher
daily charge but charges much less for a unit.


--
mailto: news {at} admac {dot] myzen {dot} co {dot} uk

On 25/06/2017 08:05, Graeme wrote:

I have mentioned before that we live in a house with an ex shop
attached, and both have separate electricity supplies, the ex shop using
roughly 1500 units per annum, with a daily charge of 25p per day or
91.25 pa, plus VAT.

Ignoring usage figures, I am thinking I could save the daily charge by
having the shop supply come from the house rather than a separate
supply, and save £95 pa. However, that does not include the cost of
the wiring, which I would not attempt myself. It seems, though, that I
would have to live, and live here, for a good few years before the
annual saving exceeded the initial cost. How long is a piece of string?
How many years? Ten? Twenty? More?

Probably 5 years minimum. (£500/95)

In message , Ash Burton
writes
On 25/06/2017 08:05, Graeme wrote:

How long is a piece of string? How many years? Ten? Twenty? More?

Probably 5 years minimum. (£500/95)

Do you really think 500 pounds? Without knowing the layout etc. it is
hard to judge, I realise, but with materials, labour and VAT I would
guess nearer 1000, but it is just a guess.

Difficult. Were we planning to never sell, it would probably be
worthwhile, but the house is large, and we're getting older. A new
owner may want separate supplies, to reinstate the shop or perhaps
convert it to granny flat, holiday flat or whatever. Dunno. I'm really
only thinking out loud.

--
Graeme

On 25/06/2017 09:30, Graeme wrote:
In message , Ash Burton
writes
On 25/06/2017 08:05, Graeme wrote:

How long is a piece of string? How many years? Ten? Twenty? More?

Probably 5 years minimum. (£500/95)

Do you really think 500 pounds? Without knowing the layout etc. it is
hard to judge, I realise, but with materials, labour and VAT I would
guess nearer 1000, but it is just a guess.

Difficult. Were we planning to never sell, it would probably be
worthwhile, but the house is large, and we're getting older. A new
owner may want separate supplies, to reinstate the shop or perhaps
convert it to granny flat, holiday flat or whatever. Dunno. I'm really
only thinking out loud.


If that's the case, i'd leave it as it is.

On 25/06/2017 09:30, Graeme wrote:


A new
owner may want separate supplies, to reinstate the shop or perhaps
convert it to granny flat, holiday flat or whatever. Dunno. I'm really
only thinking out loud.



Never try and second guess what a new owner will do. Your tastes and
requirements are seldom the same as someone else.
--
mailto: news {at} admac {dot] myzen {dot} co {dot} uk

In article ,
Graeme wrote:

I have mentioned before that we live in a house with an ex shop
attached, and both have separate electricity supplies, the ex shop using
roughly 1500 units per annum, with a daily charge of 25p per day or
91.25 pa, plus VAT.

Ignoring usage figures, I am thinking I could save the daily charge by
having the shop supply come from the house rather than a separate
supply, and save £95 pa. However, that does not include the cost of
the wiring, which I would not attempt myself. It seems, though, that I
would have to live, and live here, for a good few years before the
annual saving exceeded the initial cost. How long is a piece of string?
How many years? Ten? Twenty? More?

Assuming the wiring in both areas is good, you could run a new feed from
your meter to the other CU. That could be done by yourself, and the
connection by a sparks. You could measure up the run and work out the
costs of the cable, etc.

--
*Never slap a man who's chewing tobacco *

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

On Sunday, 25 June 2017 09:36:36 UTC+1, Graeme wrote:
In message , Ash Burton
writes
On 25/06/2017 08:05, Graeme wrote:

How long is a piece of string? How many years? Ten? Twenty? More?

Probably 5 years minimum. (£500/95)

Do you really think 500 pounds? Without knowing the layout etc. it is
hard to judge, I realise, but with materials, labour and VAT I would
guess nearer 1000, but it is just a guess.

Difficult. Were we planning to never sell, it would probably be
worthwhile, but the house is large, and we're getting older. A new
owner may want separate supplies, to reinstate the shop or perhaps
convert it to granny flat, holiday flat or whatever. Dunno. I'm really
only thinking out loud.

On what planet would a run of cable cost you £500 or £1000? 2 new CUs as well would get you nowhere near that.


NT

On 25/06/2017 11:22, wrote:
On Sunday, 25 June 2017 09:36:36 UTC+1, Graeme wrote:
In message , Ash Burton
writes
On 25/06/2017 08:05, Graeme wrote:

How long is a piece of string? How many years? Ten? Twenty? More?

Probably 5 years minimum. (£500/95)

Do you really think 500 pounds? Without knowing the layout etc. it is
hard to judge, I realise, but with materials, labour and VAT I would
guess nearer 1000, but it is just a guess.

Difficult. Were we planning to never sell, it would probably be
worthwhile, but the house is large, and we're getting older. A new
owner may want separate supplies, to reinstate the shop or perhaps
convert it to granny flat, holiday flat or whatever. Dunno. I'm really
only thinking out loud.

On what planet would a run of cable cost you £500 or £1000? 2 new CUs as well would get you nowhere near that.


NT


The OP stated explicitly he would not attempt the work himself.

2x 100A one way sf units plus say 10 m of 16mm2 swa cable and 4 hrs
labour could easily come to circa £400 plus VAT

In message ,
writes
On Sunday, 25 June 2017 09:36:36 UTC+1, Graeme wrote:

Do you really think 500 pounds? Without knowing the layout etc. it is
hard to judge, I realise, but with materials, labour and VAT I would
guess nearer 1000, but it is just a guess.

On what planet would a run of cable cost you £500 or £1000? 2 new CUs
as well would get you nowhere near that.

I honestly don't know. Why would I need 2 new CUs too? My thoughts
were to merely (!) extend the current circuits, one lighting the other
power, by cutting in somewhere in the house, and taking both ends of the
ring into the shop, and do the same there. You are thinking taking a
new feed from the house CU and running that direct to the shop CU, but
bypassing, or disconnecting the shop meter? I assume the supplier would
just disconnect outside somewhere, although they would probably remove
the meter (I assume) and charge for doing so.
--
Graeme

In article ,
Graeme wrote:
In message ,
writes
On Sunday, 25 June 2017 09:36:36 UTC+1, Graeme wrote:

Do you really think 500 pounds? Without knowing the layout etc. it is
hard to judge, I realise, but with materials, labour and VAT I would
guess nearer 1000, but it is just a guess.

On what planet would a run of cable cost you £500 or £1000? 2 new CUs
as well would get you nowhere near that.

I honestly don't know. Why would I need 2 new CUs too? My thoughts
were to merely (!) extend the current circuits, one lighting the other
power, by cutting in somewhere in the house, and taking both ends of the
ring into the shop, and do the same there. You are thinking taking a
new feed from the house CU and running that direct to the shop CU, but
bypassing, or disconnecting the shop meter? I assume the supplier would
just disconnect outside somewhere, although they would probably remove
the meter (I assume) and charge for doing so.

It would be neater to change everything to one new CU - but not needed.
Unless you must get rid of the second one for other reasons - like needing
the space or whatever. Obviously the second meter would be removed.

--
*What was the best thing before sliced bread?

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

On 25/06/2017 08:05, Graeme wrote:

I have mentioned before that we live in a house with an ex shop
attached, and both have separate electricity supplies, the ex shop using
roughly 1500 units per annum, with a daily charge of 25p per day or
91.25 pa, plus VAT.

Ignoring usage figures, I am thinking I could save the daily charge by
having the shop supply come from the house rather than a separate
supply, and save £95 pa. However, that does not include the cost of
the wiring, which I would not attempt myself. It seems, though, that I
would have to live, and live here, for a good few years before the
annual saving exceeded the initial cost. How long is a piece of string?
How many years? Ten? Twenty? More?

I would suggest getting 3 proper quotes then you would know the cost.

I would not worry about a future purchaser wanting to split the house.
If you think you might do this yourself you could retain both supply
cables.


--
Michael Chare

---
This email has been checked for viruses by Avast antivirus software.
https://www.avast.com/antivirus

On 25/06/2017 12:33, Michael Chare wrote:
On 25/06/2017 08:05, Graeme wrote:

I have mentioned before that we live in a house with an ex shop
attached, and both have separate electricity supplies, the ex shop
using roughly 1500 units per annum, with a daily charge of 25p per day
or 91.25 pa, plus VAT.

Ignoring usage figures, I am thinking I could save the daily charge by
having the shop supply come from the house rather than a separate
supply, and save £95 pa. However, that does not include the cost of
the wiring, which I would not attempt myself. It seems, though, that
I would have to live, and live here, for a good few years before the
annual saving exceeded the initial cost. How long is a piece of
string? How many years? Ten? Twenty? More?

I would suggest getting 3 proper quotes then you would know the cost.

I would not worry about a future purchaser wanting to split the house.
If you think you might do this yourself you could retain both supply
cables.


The DNO is unlikely to allow that if the OP doesn't want to pay the
daily standing charge.

On Sun, 25 Jun 2017 08:05:01 +0100, Graeme wrote:

the ex shop using roughly 1500 units per annum, with a daily charge of
25p per day or 91.25 pa, plus VAT.

Find a tarrif with no standing charge? What is the current per kWHr
cost?

If it's more than 10p/kWhr think about changing to EBICO. EBICO don't
have a standing charge but their unit rate is 16.42p/kWHr that would
give an annual bill of £245 ish (same as 10p/kWhr + 25p day).

Other suppliers my have no standing charge tarrifs with a lower per
kWhr cost. nPower did.

As far as the wiring is concerned I'd split the tails on the house
supply with a Henley block, fit a switch fuse in the fed to the shop
CU, substitute this fed for the shop supply, "park" the shop supply
in another Henley block and switch to a no-standing charge tariff on
the shop supply. No use = no cost...

Then sit back a wait for the supplier to query the zero use. If/when
they do say you don't use it (true) and don't need it (true) and if
they want to disconnect, at no cost to you, they can. (Or not if you
want to retain the supply for future eventualties).

--
Cheers
Dave.

On 25/06/2017 10:45, alan_m wrote:
On 25/06/2017 09:30, Graeme wrote:


A new owner may want separate supplies, to reinstate the shop or
perhaps convert it to granny flat, holiday flat or whatever. Dunno.
I'm really only thinking out loud.



Never try and second guess what a new owner will do. Your tastes and
requirements are seldom the same as someone else.

While true, there s no point in worrying too much about what suits
*them* best. When its their turn, they can change it how they like. It
seems unlikely it will even figure in the purchasing decision, let alone
be a deciding factor.


--
Cheers,

John.

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

In article l.net,
Dave Liquorice wrote:
Then sit back a wait for the supplier to query the zero use. If/when
they do say you don't use it (true) and don't need it (true) and if
they want to disconnect, at no cost to you, they can. (Or not if you
want to retain the supply for future eventualties).

With two supplies, just tell them you no longer need one of them?

My house had been split into two supplies when I bought it. Mother and
daughter lived there - and didn't trust one another to pay a fair share.
;-)

When I re-wired and went to one meter, the leccy company disconnected and
removed the not needed one for free. I'd guess they don't want unused ones
floating around the system.

--
*See no evil, Hear no evil, Date no evil.

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

On Sunday, 25 June 2017 11:52:24 UTC+1, Graeme wrote:
In message ,
tabbypurr writes
On Sunday, 25 June 2017 09:36:36 UTC+1, Graeme wrote:

Do you really think 500 pounds? Without knowing the layout etc. it is
hard to judge, I realise, but with materials, labour and VAT I would
guess nearer 1000, but it is just a guess.

On what planet would a run of cable cost you £500 or £1000? 2 new CUs
as well would get you nowhere near that.

I honestly don't know. Why would I need 2 new CUs too? My thoughts
were to merely (!) extend the current circuits, one lighting the other
power, by cutting in somewhere in the house, and taking both ends of the
ring into the shop, and do the same there.

Then your cost is cable & cable clips. Under £100.

You are thinking taking a
new feed from the house CU and running that direct to the shop CU, but
bypassing, or disconnecting the shop meter? I assume the supplier would
just disconnect outside somewhere, although they would probably remove
the meter (I assume) and charge for doing so.

Do you need to pay them to do that? Just cease purchasing that supply.


NT

On 25/06/2017 09:30, Graeme wrote:
In message , Ash Burton
writes
On 25/06/2017 08:05, Graeme wrote:

How long is a piece of string? How many years? Ten? Twenty? More?

Probably 5 years minimum. (£500/95)

Do you really think 500 pounds? Without knowing the layout etc. it is
hard to judge, I realise, but with materials, labour and VAT I would
guess nearer 1000, but it is just a guess.

Difficult. Were we planning to never sell, it would probably be
worthwhile, but the house is large, and we're getting older. A new
owner may want separate supplies, to reinstate the shop or perhaps
convert it to granny flat, holiday flat or whatever. Dunno. I'm really
only thinking out loud.


Easy peasy. Turn the mains off at the shop consumer unit. Make up a
cable with a 13A plug on both ends.

You know the rest...

I'll get my coat

Bill

On 25/06/2017 14:38, Dave Plowman (News) wrote:
In article l.net,
Dave Liquorice wrote:
Then sit back a wait for the supplier to query the zero use. If/when
they do say you don't use it (true) and don't need it (true) and if
they want to disconnect, at no cost to you, they can. (Or not if you
want to retain the supply for future eventualties).

With two supplies, just tell them you no longer need one of them?

My house had been split into two supplies when I bought it. Mother and
daughter lived there - and didn't trust one another to pay a fair share.
;-)

When I re-wired and went to one meter, the leccy company disconnected and
removed the not needed one for free. I'd guess they don't want unused ones
floating around the system.

My parents, along with an uncle and aunt, own a house in France, it has
a single supply, but we bought our own meter for one half when we split
the house in two. The total bill is received on the "proper" meter, the
standing charge is split equally and then the unit charge split by
useage. One, supply, one standing charge.

SteveW

On 25/06/2017 11:44, Graeme wrote:
In message ,
writes
On Sunday, 25 June 2017 09:36:36 UTC+1, Graeme wrote:

Do you really think 500 pounds? Without knowing the layout etc. it is
hard to judge, I realise, but with materials, labour and VAT I would
guess nearer 1000, but it is just a guess.

On what planet would a run of cable cost you £500 or £1000? 2 new CUs
as well would get you nowhere near that.

I honestly don't know. Why would I need 2 new CUs too? My thoughts
were to merely (!) extend the current circuits, one lighting the other
power, by cutting in somewhere in the house, and taking both ends of the
ring into the shop, and do the same there. You are thinking taking a
new feed from the house CU and running that direct to the shop CU, but
bypassing, or disconnecting the shop meter? I assume the supplier would
just disconnect outside somewhere, although they would probably remove
the meter (I assume) and charge for doing so.


Actually feeding the shop CU from an MCB from the house CU was my first
thought.

Then you cancel the contract on the shop electrics and it's then up to
the supplier what they do with their meter and their supply but whatever
they decide it's not going to cost you unless you specifically ask for
the supply to be removed.

They usually just remove the fuse and meter and leave you with an sealed
supply cutout that only needs the seal cutting and a £3 fuse fitting to
make it operable again. Not that that could be of any use to anyone with
bad intentions cough.

--
Adam

On 25/06/2017 12:41, Ash Burton wrote:
On 25/06/2017 12:33, Michael Chare wrote:
On 25/06/2017 08:05, Graeme wrote:

I have mentioned before that we live in a house with an ex shop
attached, and both have separate electricity supplies, the ex shop
using roughly 1500 units per annum, with a daily charge of 25p per
day or 91.25 pa, plus VAT.

Ignoring usage figures, I am thinking I could save the daily charge
by having the shop supply come from the house rather than a separate
supply, and save £95 pa. However, that does not include the cost of
the wiring, which I would not attempt myself. It seems, though, that
I would have to live, and live here, for a good few years before the
annual saving exceeded the initial cost. How long is a piece of
string? How many years? Ten? Twenty? More?

I would suggest getting 3 proper quotes then you would know the cost.

I would not worry about a future purchaser wanting to split the house.
If you think you might do this yourself you could retain both supply
cables.


The DNO is unlikely to allow that if the OP doesn't want to pay the
daily standing charge.


Well if the DNO want to remove the unused supply (if the OP decides to
use only one supply) then they have every right to do so. But they have
to pay for it's removal and not the OP.

Depending on how the OPs incoming supply is done that could mean
digging up pavements or worse still digging up roads.


--
Adam

On 25/06/2017 11:22, wrote:
On Sunday, 25 June 2017 09:36:36 UTC+1, Graeme wrote:
In message , Ash Burton
writes
On 25/06/2017 08:05, Graeme wrote:

How long is a piece of string? How many years? Ten? Twenty? More?

Probably 5 years minimum. (£500/95)

Do you really think 500 pounds? Without knowing the layout etc. it is
hard to judge, I realise, but with materials, labour and VAT I would
guess nearer 1000, but it is just a guess.

Difficult. Were we planning to never sell, it would probably be
worthwhile, but the house is large, and we're getting older. A new
owner may want separate supplies, to reinstate the shop or perhaps
convert it to granny flat, holiday flat or whatever. Dunno. I'm really
only thinking out loud.

On what planet would a run of cable cost you £500 or £1000?

Two words

Russ Andrews


--
Adam

In message , ARW
writes

Depending on how the OPs incoming supply is done that could mean
digging up pavements or worse still digging up roads.

Incoming supply is overhead, which makes life easier.

Thanks for all the comments - very useful. It seems that the whole job
could make economic sense. I like the idea of just running one fat
cable from the house CU through to the shop, and powering everything
from that. The shop usage is fairly minimal, just power sockets, alarm
and lighting, ie no showers, cookers etc.

Disruption should be minimal. Take the cable from a spare outlet on the
house CU and, at the shop end, remove the tails from the meter to the
CU, and connect the cable to the CU. No need to remove the shop end CU,
switches etc.

--
Graeme

On Mon, 26 Jun 2017 08:48:26 +0100, Graeme wrote:

It seems that the whole job could make economic sense.

Switching the shop to supply to a no cost option (remove it or no
standing charge tarrif with zero use) gives you £245/year, less cost
of 1500 units on the house supply, perhaps £100/year. guesstimate
£400 to get the work done, 4 years...


Disruption should be minimal. Take the cable from a spare outlet on the
house CU ...

Snag with that is if you turn off the house supply for any reason the
shop goes off as well. Split the tails, fit the required switch fuse
into the sub-main to the shop CU and the shop can be on with the
house off or vice versa.

--
Cheers
Dave.

In message l.net,
Dave Liquorice writes
On Mon, 26 Jun 2017 08:48:26 +0100, Graeme wrote:

Disruption should be minimal. Take the cable from a spare outlet on the
house CU ...

Snag with that is if you turn off the house supply for any reason the
shop goes off as well. Split the tails, fit the required switch fuse
into the sub-main to the shop CU and the shop can be on with the
house off or vice versa.

Even better! Yes, cutting the power to the shop always sends the alarm
into a tizzy, so best avoided if possible. It is an ex Post Office, so
fully alarmed even though no longer in service.
--
Graeme

On 26/06/2017 15:44, Graeme wrote:


Even better! Yes, cutting the power to the shop always sends the alarm
into a tizzy, so best avoided if possible. It is an ex Post Office, so
fully alarmed even though no longer in service.

Power cuts setting off alarms are often cured by replacing the battery
in the alarm control box.

--
mailto: news {at} admac {dot] myzen {dot} co {dot} uk

On 26/06/2017 12:39, Dave Liquorice wrote:

Snag with that is if you turn off the house supply for any reason the
shop goes off as well. Split the tails, fit the required switch fuse
into the sub-main to the shop CU and the shop can be on with the
house off or vice versa.


It's not much of a snag is it?

How often does the average householder have to turn the house supply off?

--
Adam

On 26/06/2017 08:48, Graeme wrote:
In message , ARW
writes

Depending on how the OPs incoming supply is done that could mean
digging up pavements or worse still digging up roads.

Incoming supply is overhead, which makes life easier.

Thanks for all the comments - very useful. It seems that the whole job
could make economic sense. I like the idea of just running one fat
cable from the house CU through to the shop, and powering everything
from that. The shop usage is fairly minimal, just power sockets, alarm
and lighting, ie no showers, cookers etc.

Disruption should be minimal. Take the cable from a spare outlet on the
house CU and, at the shop end, remove the tails from the meter to the
CU, and connect the cable to the CU. No need to remove the shop end CU,
switches etc.


I know it's not much load, 1500 unit pa.

--
Adam

On Mon, 26 Jun 2017 19:01:26 +0100, ARW wrote:

Take the cable from a spare outlet on the house CU and, at the
shop
end, remove the tails from the meter to the CU, and connect the
cable
to the CU. No need to remove the shop end CU, switches etc.

I know it's not much load, 1500 unit pa.

Poor assumption, it could be a 16 kW load for 30 mins every other
day:

16 * 0.5 * (365 / 2) = 1460 kWhr.

The 24/7 load is a mere 170 W (0.17 * 24 * 365 = 1489 kWHr).

In reality the peak load will be somewhere between the two, maybe 4
kW for a kettle plus a 1 kW of other load but remember *everything*
is going through that single MCB in the house CU, so you loose
diversity. Overload the house CU MCB and everything goes off in the
shop. Overload an MCB in the shop CU fed with a sub-main only that
MCB goes off, perhaps the lights stay on...

Not mention that having a seperate supply available when the other is
off for some reason is handy.

--
Cheers
Dave.

On Monday, 26 June 2017 21:23:59 UTC+1, Dave Liquorice wrote:

kW for a kettle plus a 1 kW of other load but remember *everything*
is going through that single MCB in the house CU, so you loose
diversity. Overload the house CU MCB and everything goes off in the
shop. Overload an MCB in the shop CU fed with a sub-main only that
MCB goes off, perhaps the lights stay on...

Not mention that having a seperate supply available when the other is
off for some reason is handy.

It depends. If you have say a 32A & 6A shop circuit fed from a 38A MCB then you're unlikely to trip both circuits if one trips.


NT

On 26/06/2017 21:23, Dave Liquorice wrote:
On Mon, 26 Jun 2017 19:01:26 +0100, ARW wrote:

Take the cable from a spare outlet on the house CU and, at the
shop
end, remove the tails from the meter to the CU, and connect the
cable
to the CU. No need to remove the shop end CU, switches etc.

I know it's not much load, 1500 unit pa.

Poor assumption, it could be a 16 kW load for 30 mins every other
day:

16 * 0.5 * (365 / 2) = 1460 kWhr.

The 24/7 load is a mere 170 W (0.17 * 24 * 365 = 1489 kWHr).

In reality the peak load will be somewhere between the two, maybe 4
kW for a kettle plus a 1 kW of other load but remember *everything*
is going through that single MCB in the house CU, so you loose
diversity. Overload the house CU MCB and everything goes off in the
shop. Overload an MCB in the shop CU fed with a sub-main only that
MCB goes off, perhaps the lights stay on...

Not mention that having a seperate supply available when the other is
off for some reason is handy.


It's not a poor assumption. The OP has already said that there are no
high load circuits such as cookers or showers in the (ex) shop. He has
also suggested that the shops sockets power could be integrated into the
house circuit by extending the house circuit ring to incorporate the
shop ring and similar for the lights.

Supplying everything through one MCB or fuse is a good example of how
diversity is applied and is not a loss of diversity.


--
Adam

On 26/06/2017 22:28, wrote:
On Monday, 26 June 2017 21:23:59 UTC+1, Dave Liquorice wrote:

kW for a kettle plus a 1 kW of other load but remember *everything*
is going through that single MCB in the house CU, so you loose
diversity. Overload the house CU MCB and everything goes off in the
shop. Overload an MCB in the shop CU fed with a sub-main only that
MCB goes off, perhaps the lights stay on...

Not mention that having a seperate supply available when the other is
off for some reason is handy.

It depends. If you have say a 32A & 6A shop circuit fed from a 38A MCB then you're unlikely to trip both circuits if one trips.



Not if it's a fault current:-)

--
Adam

In message , alan_m
writes
On 26/06/2017 15:44, Graeme wrote:

Even better! Yes, cutting the power to the shop always sends the
alarm into a tizzy, so best avoided if possible. It is an ex Post
Office, so fully alarmed even though no longer in service.

Power cuts setting off alarms are often cured by replacing the battery
in the alarm control box.

The battery is fine. The alarm does not go off, but the control box
emits constant warning beeps, and requires resetting.
--
Graeme

In message , ARW
writes

It's not a poor assumption. The OP has already said that there are no
high load circuits such as cookers or showers in the (ex) shop. He has
also suggested that the shops sockets power could be integrated into
the house circuit by extending the house circuit ring to incorporate
the shop ring and similar for the lights.

Quite right. I don't use anything high powered in there, not even a
kettle. However, I am aware that, should the house be sold at any time,
a new owner may behave differently, so both power and lighting circuits
must be up to normal spec. Having said that, if anyone in the future
converted it to, say, a granny flat, it is not unreasonable to assume
they would check carefully and install new runs if installing, say, a
power shower.

--
Graeme

On Monday, 26 June 2017 23:22:59 UTC+1, ARW wrote:
On 26/06/2017 22:28, tabbypurr wrote:
On Monday, 26 June 2017 21:23:59 UTC+1, Dave Liquorice wrote:

kW for a kettle plus a 1 kW of other load but remember *everything*
is going through that single MCB in the house CU, so you loose
diversity. Overload the house CU MCB and everything goes off in the
shop. Overload an MCB in the shop CU fed with a sub-main only that
MCB goes off, perhaps the lights stay on...

Not mention that having a seperate supply available when the other is
off for some reason is handy.

It depends. If you have say a 32A & 6A shop circuit fed from a 38A MCB then you're unlikely to trip both circuits if one trips.



Not if it's a fault current:-)

The graphs at
http://wiki.diyfaq.org.uk/index.php/MCB
show that discrimination is normally obtained with fault currents.


NT

On 26/06/2017 23:19, ARW wrote:


Supplying everything through one MCB or fuse is a good example of how
diversity is applied and is not a loss of diversity.



I think he meant discrimination.

On 27/06/2017 09:34, wrote:
On Monday, 26 June 2017 23:22:59 UTC+1, ARW wrote:
On 26/06/2017 22:28, tabbypurr wrote:
On Monday, 26 June 2017 21:23:59 UTC+1, Dave Liquorice wrote:

kW for a kettle plus a 1 kW of other load but remember *everything*
is going through that single MCB in the house CU, so you loose
diversity. Overload the house CU MCB and everything goes off in the
shop. Overload an MCB in the shop CU fed with a sub-main only that
MCB goes off, perhaps the lights stay on...

Not mention that having a seperate supply available when the other is
off for some reason is handy.

It depends. If you have say a 32A & 6A shop circuit fed from a 38A MCB then you're unlikely to trip both circuits if one trips.



Not if it's a fault current:-)

The graphs at
http://wiki.diyfaq.org.uk/index.php/MCB
show that discrimination is normally obtained with fault currents.

not all fault currents have looked at the graph though ;-)


--
Cheers,

John.

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On Tuesday, 27 June 2017 14:05:49 UTC+1, John Rumm wrote:
On 27/06/2017 09:34, tabbypurr wrote:
On Monday, 26 June 2017 23:22:59 UTC+1, ARW wrote:
On 26/06/2017 22:28, tabbypurr wrote:
On Monday, 26 June 2017 21:23:59 UTC+1, Dave Liquorice wrote:

kW for a kettle plus a 1 kW of other load but remember *everything*
is going through that single MCB in the house CU, so you loose
diversity. Overload the house CU MCB and everything goes off in the
shop. Overload an MCB in the shop CU fed with a sub-main only that
MCB goes off, perhaps the lights stay on...

Not mention that having a seperate supply available when the other is
off for some reason is handy.

It depends. If you have say a 32A & 6A shop circuit fed from a 38A MCB then you're unlikely to trip both circuits if one trips.



Not if it's a fault current:-)

The graphs at
http://wiki.diyfaq.org.uk/index.php/MCB
show that discrimination is normally obtained with fault currents.

not all fault currents have looked at the graph though ;-)

In most cases discrimination will be maintained. The fact that ocasionally it isn't is rather trivial, and hardly worth a protracted discussion. The op knows the options.


NT

On 27/06/2017 19:51, wrote:
On Tuesday, 27 June 2017 14:05:49 UTC+1, John Rumm wrote:
On 27/06/2017 09:34, tabbypurr wrote:
On Monday, 26 June 2017 23:22:59 UTC+1, ARW wrote:
On 26/06/2017 22:28, tabbypurr wrote:
On Monday, 26 June 2017 21:23:59 UTC+1, Dave Liquorice wrote:

kW for a kettle plus a 1 kW of other load but remember *everything*
is going through that single MCB in the house CU, so you loose
diversity. Overload the house CU MCB and everything goes off in the
shop. Overload an MCB in the shop CU fed with a sub-main only that
MCB goes off, perhaps the lights stay on...

Not mention that having a seperate supply available when the other is
off for some reason is handy.

It depends. If you have say a 32A & 6A shop circuit fed from a 38A MCB then you're unlikely to trip both circuits if one trips.



Not if it's a fault current:-)

The graphs at
http://wiki.diyfaq.org.uk/index.php/MCB
show that discrimination is normally obtained with fault currents.

not all fault currents have looked at the graph though ;-)

In most cases discrimination will be maintained. The fact that ocasionally it isn't is rather trivial, and hardly worth a protracted discussion. The op knows the options.




How on earth can you say "in most cases discrimination will be
maintained" from those graphs and keep a straight face?


--
Adam

On 27/06/2017 19:51, wrote:
On Tuesday, 27 June 2017 14:05:49 UTC+1, John Rumm wrote:
On 27/06/2017 09:34, tabbypurr wrote:
On Monday, 26 June 2017 23:22:59 UTC+1, ARW wrote:
On 26/06/2017 22:28, tabbypurr wrote:
On Monday, 26 June 2017 21:23:59 UTC+1, Dave Liquorice
wrote:

kW for a kettle plus a 1 kW of other load but remember
*everything* is going through that single MCB in the house
CU, so you loose diversity. Overload the house CU MCB and
everything goes off in the shop. Overload an MCB in the
shop CU fed with a sub-main only that MCB goes off, perhaps
the lights stay on...

Not mention that having a seperate supply available when
the other is off for some reason is handy.

It depends. If you have say a 32A & 6A shop circuit fed from
a 38A MCB then you're unlikely to trip both circuits if one
trips.



Not if it's a fault current:-)

The graphs at http://wiki.diyfaq.org.uk/index.php/MCB show that
discrimination is normally obtained with fault currents.

not all fault currents have looked at the graph though ;-)

In most cases discrimination will be maintained. The fact that
ocasionally it isn't is rather trivial, and hardly worth a protracted
discussion. The op knows the options.

In many cases of *overload*, discrimination will be maintained - at
least with a single downstream MCB one rating step or more lower than
upstream.

With multiple MCBs downstream (say a CU on a submain) its probably still
likely - but somewhat less so.

However with a 500A fault current why would you expect the magnetic
response of the lower trip current device to be necessarily faster than
that of the higher rating device?

(its for this reason one often elects to use a HRC fuse for the head end
of a submain)

--
Cheers,

John.

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| Internode Ltd - http://www.internode.co.uk |
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