Electricity Saving Boxes, scam or not?

[bernardgreen]

Reduction in current but as BAS has said the over all power used will be the same ( things take longer to heat up so the current is lower but the time is longer )

 

[westie101]

These boxes can only cope with a small load ( less than one or two kilowatts ) and the better ones will switch themselves out when overloaded. The cheaper ones just get hot and melt out.

These boxes can cope with the normal load seen in a domestic situation (up to 100A) based on the one I had to deal with that had been installed

 

[JohnW2]

Reduction in current but as BAS has said the over all power used will be the same ( things take longer to heat up so the current is lower but the time is longer )

Indeed. In fact, it's quite possible with some of these loads that the total amount of power used will be a little greater - since slower heating up may give more scope for heat losses.

Kind Regards, John

 

[ericmark]

Where the power used compared with voltage is linear these units can't really help. Two places where they can help is with non switch mode power supplies and florescent lamps using wire wound ballast control.

Before the HF ballast became cheap enough to use the auto transformer which regulated to supply to florescent lighting for large buildings did save a lot of money.

However things have moved on and with HF florescent and switch mode power supplies these units have become in the main redundant. I am sure the Model T Ford was very good in it's day and there are likely still some in use. But no one in their right mind would try and market these as new cars today. The same with the auto stepping auto transformer it was a good idea in its day but that day has gone.

 

[JohnW2]

Where the power used compared with voltage is linear these units can't really help. Two places where they can help is with non switch mode power supplies and florescent lamps using wire wound ballast control.

Even those two examples you mention are probably not straightforward. If the non-switched-mode PSU is regulated, then you're probably right - since reduced supply voltage will reduce losses as heat in the regulation circuitry. However, if the PSU is not regulated, then the consequences will depend crucially on the nature (and control) of it's load - and, even when 'power saving' achieved, it may be at the price of reduced 'performance'.

As for traditional fluorescent ballasts, then I would think that (assuming kWh, rather than VAh were being metered) it is only losses due to the resistive component of the ballast that should be significantly reduced - since the voltage drop due to the reactance of the ballast ought to be 'wattless'. Isn't that the case?

Kind Regards, John