another household electrical question.

[sparkymarky]

Perhaps a sightly different electrical question, and more for any electrical engineers.

I have a boiler it had blown its circuit board.
the supply is on a plug which goes into a two gang socket point the other socket is plugged into a tumble drier. when the tumble drier is turned on or off i have recorded a voltage spike up to 283 volts from a normal 244 volts.
The customer has consulted 3 electricians + western power (national grid) who has done voltage recording on his mains over 8 days and said that although higher on the 240 volt range it is well within limits. all electrics have been checked in the house and have said to be ok.
My suggestion was to install a 5amp supply direct from the consumer unit incase any capacitors on the 13amp ring main (on washing machines ect) was causing interference, but the customers electrician said it wouldn`t make any difference.
I have also consulted a couple other electricians who were also stumped.

Interested to see if anyone has a response to this conundrum.

Cheers, Mark.

 

[Racers]

Hi, Mark

You need a surge suppressor.

Pete

 

[Digit]

283 v is well within tolerance Mark, BUT that depends on how the reading was obtained. A digital meter needs time and records an average figure and an analog meter has to overcome the needle inertia and again records below peak voltage.
Frankly I suspect the peak is very much higher than 283 v. A good scope would probably give you a more exact figure.
I've had over 80 v from a 9 volt supply!
The easiest solution would be, subject to the customer's agreement, a DP switched socket for the boiler and turn the boiler off when the spin dryer is in use.

Roy.

 

[sparkymarky]

thanks for the replies, i have been told by an electrician that a surge suppressor is just a gimmick and doesn't help to regulate the voltage 100% of the time, is this right??

The voltage was read on a digital multimeter so the voltage may well of been higher + the boiler is a combi so not really ideal to turn it off, it does have a dp switch on the panel though.

I should of said fixing the boiler isnt a issue i can just replace all the current control panel with a uprated panel which doesn`t have any similar surge weakness as the old boards. whats puzzling me is that 5 electricians + western power cant seem figure out what`s causing the surge.

mark.

 

[Digit]

is this right??

Yes. Depending on the spin dryer Mark it is rather unlikely that it has a filter built in, most washing machines do.
The surge is caused by what is called 'Ringing', any inductive component that has its supply cut quickly will 'Ring.'
Washing machines normally have a DP switch plus a filter to stop it spreading down the line.
Ringing has uses as well as disadvantages but I'm surpised that the boiler PC board wasn't protected, if the new one is why not leave it at that?

Roy.