On 11 Nov 2008 23:40:59 GMT, (Andrew
Gabriel) wrote:

In article ,
Peter Parry writes:
On Tue, 11 Nov 2008 21:17:23 +0000, Hugh Jampton
wrote:

I changed my dual fuel tariff with EON recently. New one is fixed until
next October. With my new deal came a "Energy saving monitor" - it tells me
how much electricity I'm using.

I've checked the readings of the monitor against my meter readings. The
monitor tells me I'm using approx. 15% less than my meter readings.

Are these monitors that inaccurate ? Or could my meter be over reading my
usage ?

The "whole house" monitors which clip over one of the feeds to the
electricity meter and have a remote reader are really quite
inaccurate, vastly more so than the meter. They are mainly greenwash
where being seen to be doing something is considerably more important
than actually achieving something.

They can't measure power at all -- the reading is a guess.
They can only measure current, and then have to guess the
voltage and phase angle to estimate the power.


Part of the set up for the electrisave allows you to set the mains
voltage from 220v to 250v in 10v increments. If you know the voltage
and it is reasonably constant this type, at least should be reasonably
accurate if the power factor is cloes to 1.

They're perfectly reasonable devices that give a rough guide to
consumption without having to log meter readings all the time. They
can also remind you if you've left 300w of light on in that room that
you only go into once a month!