Mains Voltage Around the Country

[david]

Interesting article about volts around the country. I had 253v last night!

There are huge variations in the voltage supplied within the UK. If you live in Hampshire you may only have 213v and in the North East it could be 250v. The suppliers of your electricity are only required to deliver 230v +10%-6%. That means if it’s between 216v and 253v that’s fine. Obviously voltage variation has implications for the equipment we use in our homes. This may manifest itself in equipment running hotter than intended due to higher than expected voltage, or lights being dimmer than normal due to lower voltage. If the actual supply is higher than necessary for proper operation, the equipment will consume more power than needed, and in many cases life is reduced - both increasing the cost of ownership. The UK Government is of the view that “equipment placed on the market in the UK must be safe at the operating voltages which the equipment will find itself exposed.” That sounds like a very reasonable stance to take and if I’d seen signs of this policy being followed or even publicised I’d probably be reassured.

[Richard]

Yep this still comes up from time to time. I guess it's of little importance when most domestic equipment copes ok with the variation but the previous WAD designs run the valves near max rating. I've had problems with 2 in particular being Kit88 and 300Bpp stereo but small circuit adjustments soon fixed them (note these are not the present WD amps which are all fine in this area).

It has been pointed out on this bb many times that the first check to make on an amp is to see what local mains volts you're feeding it. Mains in a city or industrial area might well be different to being on one end or the other of a local supply out in the countryside. It's also interesting to check voltage at different times in the day when I've found quite large differences. Really though any problem means we are trying to run the valves too close to their max. Look at old amps such as Quad II with legendary reliability and see they run them very conservatively.

In the case of the 300Bpp clones all those seem to have higher HTV than the original amps. The original circuit shows a 240V mains TX primary and if it was then developed and tested in an area getting 230V mains the resulting HT would have been lower. The clone builders all report high HTV so, only a guess, but I wonder if the later TXs were wound with 230V primary as would have become the norm between the original design in 1994 and say 2004.

None of this matters much though so long as we are aware and make any needed adjustment when we build as you've now done

[FreddieT]

Following a power cut recently we were restored to a partial supply of about 165V for a hour or so. Some items of equipment work (switched mode supplied mostly) and some don't and some don't like it as they keep powering up and back down! After a short while we went off again and on restoration we were at are usual 235V or so. Unfortunately this was about midnight and led to a dash around the house switching things off or back on despite having retired for the night. Took the time to measure the voltage though!

At our old house I complained to the local electricity board (this was pre privatization so in the early 1990s) that our supply was dropping to 185V at the meter terminals when the oven was on and it was playing havoc with the hi fi and the speed my dinner was being cooked! They didn't believe the reading (my meter was calibrated but they wouldn't accept the reading) and said that there was a £35 call out charge to check which was non refundable even if it was a high resistance the supply side of the meter. I pointed out that somewhere a considerable amount of heat being generated (minimal load 230V) and why should I pay for a fault in their cable. In the end we moved without a resolution (drastic measures) as they deployed massive delaying tactics.

Best mains I ever had? Before any of the other houses on our estate were occupied; a whole sub station to ourselves. No neighbours but great mains.
F.