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Old 17-03-2011, 12:26
ray_01
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I don't know where to post this, but the other night we had a local power cut for about a minute.
My Sky-box upstairs went off along with lights etc.and had to be restarted,but downstairs my Sky-box along with tv,cooker clock and a normally sensitive trip for outside pond pump stayed on.Anyone know how this could happen?
Neighbouring houses were affected by the cut but I don't if they only had a partial cut like mine.
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Old 17-03-2011, 12:41
grahamlthompson
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I don't know where to post this, but the other night we had a local power cut for about a minute.
My Sky-box upstairs went off along with lights etc.and had to be restarted,but downstairs my Sky-box along with tv,cooker clock and a normally sensitive trip for outside pond pump stayed on.Anyone know how this could happen?
Neighbouring houses were affected by the cut but I don't if they only had a partial cut like mine.
Do you by any chance have 2 phases connected rather than the normal one ?
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Old 17-03-2011, 12:49
joshua_welby
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Do you by any chance have 2 phases connected rather than the normal one ?
What is a "Phase"?
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Old 17-03-2011, 13:12
Nigel Goodwin
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It's a basic electricity connection term.

Electricity in the UK is distributed as three phase, with industrial premises having all three phases connected (for the massively increased power capabilty), and domestic premises only having a single phase connected.

In order to spread the load equally houses are connected to different phases, so in a normal street number 1 would be phase 1, number 3 phase 2, number 5 phase 3, and number 7 starting back at phase 1.

It would be VERY, VERY unusual for a domestic house to have different phase upstairs and downstairs - and there are fairly serious safety implications in doing so. The reason for short mains leads is so you can't can't possibly plug items in different phases and then touch both items - likewise there are strict regulations about how close sockets on different phases can be.

So assuming the OP only has a single phase (easily spotted as he will most probably only have a single meter), there's nothing external to the house that could cause a fault upstairs and not downstairs.
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Old 17-03-2011, 14:30
grahamlthompson
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It's a basic electricity connection term.

Electricity in the UK is distributed as three phase, with industrial premises having all three phases connected (for the massively increased power capabilty), and domestic premises only having a single phase connected.

In order to spread the load equally houses are connected to different phases, so in a normal street number 1 would be phase 1, number 3 phase 2, number 5 phase 3, and number 7 starting back at phase 1.

It would be VERY, VERY unusual for a domestic house to have different phase upstairs and downstairs - and there are fairly serious safety implications in doing so. The reason for short mains leads is so you can't can't possibly plug items in different phases and then touch both items - likewise there are strict regulations about how close sockets on different phases can be.

So assuming the OP only has a single phase (easily spotted as he will most probably only have a single meter), there's nothing external to the house that could cause a fault upstairs and not downstairs.
Depends on how affluent the OP is, there are lots of larger properties that have multiphase installs around Solihull. I have a mate who runs an electrical contracting business. I went to look at a house with a electrically heated pool recently with a 3 phase installation (connected to a 11 kV overhead line). The pool heater really knocks the voltage on switch on.
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Old 17-03-2011, 16:48
Nigel Goodwin
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I went to look at a house with a electrically heated pool recently with a 3 phase installation (connected to a 11 kV overhead line).
I wouldn't really consider that a 'domestic' installation

It's really an industrial supply for an industrial application, mostly I've seen use oil or gas for heating them, I don't think I've seen an electrically heated one? - probably because of the costs of running it, and having a three phase supply laid on in the first place.

In any case, it's VERY much the exception
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Old 17-03-2011, 16:55
grahamlthompson
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I wouldn't really consider that a 'domestic' installation

It's really an industrial supply for an industrial application, mostly I've seen use oil or gas for heating them, I don't think I've seen an electrically heated one? - probably because of the costs of running it, and having a three phase supply laid on in the first place.

In any case, it's VERY much the exception
You ain't seen the houses in the posh end of Solihull .

Sometimes very small installations have 3 phase supplies simply to run 3 phase motors. A friend in Stratford has a butchers shop which lives above. His walk in freezer has a 3 phase motor but it's not a particulary large load.
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Old 17-03-2011, 17:01
Nigel Goodwin
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You ain't seen the houses in the posh end of Solihull .

Sometimes very small installations have 3 phase supplies simply to run 3 phase motors. A friend in Stratford has a butchers shop which lives above. His walk in freezer has a 3 phase motor but it's not a particulary large load.
Again, industrial applications we have three phase at work, but the only three phase device is a small goods lift.

But because of the three phase supply, different parts of the buildings are on different phases - so we do lose just some parts during power cuts. It's easy to check, just try the lift, if a phase is down it just buzzes.

Thinking on, we've actually got two seperate three phase supplies incoming, from completely different directions - so we can even have parts of the buildings still powered if all three phases go down.
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Old 17-03-2011, 17:46
ray_01
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It's a basic electricity connection term.

Electricity in the UK is distributed as three phase, with industrial premises having all three phases connected (for the massively increased power capabilty), and domestic premises only having a single phase connected.

In order to spread the load equally houses are connected to different phases, so in a normal street number 1 would be phase 1, number 3 phase 2, number 5 phase 3, and number 7 starting back at phase 1.

It would be VERY, VERY unusual for a domestic house to have different phase upstairs and downstairs - and there are fairly serious safety implications in doing so. The reason for short mains leads is so you can't can't possibly plug items in different phases and then touch both items - likewise there are strict regulations about how close sockets on different phases can be.

So assuming the OP only has a single phase (easily spotted as he will most probably only have a single meter), there's nothing external to the house that could cause a fault upstairs and not downstairs.
Correct Nigel,
Only one meter.
We do get our fair share of power cuts but always the whole house.
My son who lives nearby had some lights out others on (I don't know if it was on the same floor.
Many thanks for the amusing replys.
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Old 17-03-2011, 18:14
tellytart1
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We have fun and games here, we have:
2 x 11kV 3 Phase "General" mains - direct from the national grid from two substations.
3 Phase "Tech" power, that is derived from the 11kV feeds, but is fed from generators when power fails, but isn't on UPS, then
2 x 3 Phase UPS protected power supplies again derived from incoming mains, but sustained using UPS while the generators run up.

All of which are variously available around the building, and all are available in the apparatus rooms!
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Old 18-03-2011, 22:21
kev
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I don't know where to post this, but the other night we had a local power cut for about a minute.
My Sky-box upstairs went off along with lights etc.and had to be restarted,but downstairs my Sky-box along with tv,cooker clock and a normally sensitive trip for outside pond pump stayed on.Anyone know how this could happen?
Neighbouring houses were affected by the cut but I don't if they only had a partial cut like mine.
Could it have been a brown out? The voltage here is quite low (last time I looked it fluctuated between 217 and 225V but during some nearby construction works would drop below 210) and some of my gear doesn't like it being too low so when it went to 210 it would go off but nothing else would be effected.

Don't notice nowadays as the most sensitive stuff is on a UPS or has since died, oh and the construction work has also ended.
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Old 19-03-2011, 10:54
Pugwash69
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What sort of property is it? If it's old terraces, could they have adapted flats into houses giving you an up/down property from two previous flats?
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Old 19-03-2011, 13:04
grahamlthompson
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What sort of property is it? If it's old terraces, could they have adapted flats into houses giving you an up/down property from two previous flats?
Which could mean the OP is paying for someone elses energy and vice versa
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Old 21-03-2011, 12:44
ray_01
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Which could mean the OP is paying for someone elses energy and vice versa
Thanks Graham.
It's a detatched property.
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Old 23-03-2011, 09:42
JulesandSand
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Is it always the case that 2 phases means 2 meters?
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Old 23-03-2011, 10:05
Mark C
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I wouldn't really consider that a 'domestic' installation

It's really an industrial supply for an industrial application, mostly I've seen use oil or gas for heating them, I don't think I've seen an electrically heated one? - probably because of the costs of running it, and having a three phase supply laid on in the first place.

In any case, it's VERY much the exception
It is, though my parents home is on two phases. When it was built, in 1966, it was the first house along the road. There was no gas supply either, so my father opted for electrical night storage heating. The load was so large, and the local sub station then was just a transformer on a pole, that the electricity board connected them across two phases.

As a consequence, they have four of everything, meters, consumer units, and ELCBs ! On Peak Ph 1, Off Peak Ph 1, On Peak Ph 2, Off Peak Ph 2 Dad had to build a cupboard around the installation to hide it away ! Still all there now, confuses the hell out of the young meter readers when they come round
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Old 23-03-2011, 10:21
grahamlthompson
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Is it always the case that 2 phases means 2 meters?
It is for domestic installations. The OP should turn off the main switch on his consumer unit and see if everything goes off. If not check with his neighbours if they have lost any supply.
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Old 24-03-2011, 07:23
JulesandSand
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It is for domestic installations. The OP should turn off the main switch on his consumer unit and see if everything goes off. If not check with his neighbours if they have lost any supply.
No it isn't - a friend of mine had a second phase installed recently whilst extending his house, they replaced his meter at the same time and only has one meter.
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Old 24-03-2011, 10:35
grahamlthompson
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No it isn't - a friend of mine had a second phase installed recently whilst extending his house, they replaced his meter at the same time and only has one meter.
I guess domestic metering technology has moved on since I retired from the industry. It does however confirm that multiphase installations in larger properties aren't that unusual despite what Nigel says. It's often the only way to supply larger properties fed by light line 11Kv overhead distribution.

Example here

http://www.eon-uk.com/distribution/C...rd%20Apr06.pdf
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Old 24-03-2011, 10:39
JulesandSand
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I guess domestic metering technology has moved on since i retired from the industry. It does however confirm that multiphase installations in larger properties aren't that unusual despite what Nigel says. It's often the only way to supply larger properties fed by light line 11Kv overhead distribution.
I've also just found out that I have 2 phases supplying my house. (I had no idea ) and I only have one meter.

My said friend has all electric heating. Is the second phase required because of high potential demand in a house?
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Old 24-03-2011, 10:52
grahamlthompson
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I've also just found out that I have 2 phases supplying my house. (I had no idea ) and I only have one meter.

My said friend has all electric heating. Is the second phase required because of high potential demand in a house?
Yes it's either because a large single phase load would severely unbalance the connected demand across the three phases. (Any unbalance produces a current in the neutral conductor which is much smaller than the phase conductors) or in the case of electric heating the switch on will produce an unacceptably high voltage disturbance.

The problem is much worse on overhead networks like the construction detailed in the link.
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