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Electricity Monitors

Moderator
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Electricity Monitors

I have two of these, well three actually but that's another story.
One I bought about 4 years ago and one came free from the council last month.
I have both in use and the new one reads 0.280kw and the other reads 0.300kw
Now I'm wondering which is telling the truth.
The one reading 0.300kw has adjustable AC voltage between 200 and 250, the other doesn't.
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22 REPLIES
Plusnet Help Team
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Re: Electricity Monitors

I've tried two different ones and had the same problem. One looked like quite an old device that I'd borrowed from a library in Sheffield the other came free with my electricity tarrif, I definitely trust the latter one as it's helped me bring my bills right down.
Adam
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 Adam Walker
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phil4
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Registered: 13-12-2007

Re: Electricity Monitors

I doubt either are truly correct as there's also sorts of phenomenon that can cause them to misread the true result.
I'd suggest just using them as an indication as to a) whether you're using a lot, or not, and b) what things cause it to use a lot.
Then if you're like me, you've the challenge of persuading the others in your household to pay some sort of attention to it.
itsme
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Re: Electricity Monitors

Measuring power is not easy and not sure how these monitors are connected.
Power W =VI in it's simplest form but it the voltage and current are not in phase then this will cause problems as most monitors I would assume just measure the average voltage and current and calculate the power.
Moderator
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Re: Electricity Monitors

A simple induction coil device on the live cable.
Yep there's no way I can see they can take lead and lag into account.
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itsme
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Re: Electricity Monitors

Inductive clamps unless someone correct me will produce a voltage proportional to the current flowing. So these devices must assume the voltage and as the UK grid voltage has been reduced older devices should give a higher reading.
Moderator
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Re: Electricity Monitors

...and there can be quite a variation in the voltage throughout the day which theoretically should affect both the same but...... Undecided
Customer and Forum Moderator.
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Re: Electricity Monitors

MAkes me laugh.. we're discouraged from leaving the TV on standby but encouraged to use one of these 'active' devices 24/7?  Roll eyes
I need a new signature... i'm bored of the old one!
itsme
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Re: Electricity Monitors

and 3 port mid position valves that will draw power in 2 of the 3 positions. At the moment mine is warm to the touch and the heating have not been on for over 12 hours.
kdiment
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Re: Electricity Monitors

Quote from: itsme
...  and as the UK grid voltage has been reduced ...

Not here it hasn't. A steady 246v measured this evening. I believe there are plans to make it a nominal 220v instead of 240v at some time, but I don't know when.
  - Keith
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Re: Electricity Monitors

Not exactly Keith,
it was actually 'harmionised' with Europe a few years ago - it was redefined fromm 240V +/- 6% to 230V +10%/-6% while Europe went from 220V +/-6% to 230V +6%/-10%, eventually we are all to end up at 230V +/-6%.  In reality the 230V +6% is exactly the same upper limit as 240V +10% (for practical purposes) so the electricity suppliers have generally not actually changed anything (yet), we now have a nominal 230V the same as Europe but we run at 240V and they still run at 220V, most of the pime (below peak load) you will find the supply is still generally above 240V in the UK.
For a meter to measure power it must measure voltage and current AND measure the relative phasing of the two, true RMS power meters are not too difficult to come by but are rather more expensive than these energy monitors.  Your meter that your supplier reads is (as a legal requirement) a true RMS power meter, there is one power supplier, at least, who install a smart meter that is monitored continuously and they provide graphs of usage over the internet (sorry I can't remember the company name) but they could not supply me when I enquired as I am on economy 7  Cry
Call me 'w23'
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itsme
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Re: Electricity Monitors

Quote from: walker23
there is one power supplier, at least, who install a smart meter that is monitored continuously and they provide graphs of usage over the internet (sorry I can't remember the company name) but they could not supply me when I enquired as I am on economy 7  Cry

Would it be First Utility? When did did you enquired?
I went with First Utility In October 2009 with Economy 7 with the Smart meter fitted in November but not billed using the smart meter reading until February 2009 when I then had issues with the bill, night time usage being charged at the more expensive day rate. I then noticed sometime in 2010 that they did not have tariffs for Economy 7 on their Website.
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Re: Electricity Monitors

My energy monitor is able to report -  Volts,  Amps,  Hz,  Watts,  VA,  PF (Power Factor),  KWh, and the runtime for the accumulated KWh reading.  http://www.maplin.co.uk/plug-in-mains-power-and-energy-monitor-38343
I use mine for discovering the most energy efficient components for building my PCs with.  My present main home network server only takes 6W when active ! so is not a problem leaving it switched on 24/7  Smiley

Presumably the type that 'Strat' is using, intended to help reduce electricity usage, the absolute value is actually not really that important - as the intention is to provide an ballpark indication of energy consumption and then for the consumer to see the relative results of attempts to minimise electricity usage by using low energy light bulbs or repacing the fride/freezer with an A+ rated one, etc.  Besides for a consumer rated device a 7% difference between clamp-on or induction meters is pretty good, and even that difference could be down to how well the clamp or coil was positioned.
Midnight_Caller
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Re: Electricity Monitors

Quote from: kdiment
Not here it hasn't. A steady 246v measured this evening. I believe there are plans to make it a nominal 220v instead of 240v at some time, but I don't know when.

Back in the 1970's it was 250v
VileReynard
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Re: Electricity Monitors

I think it's meant to be a nominal 230v.