New sockets keep tripping!!

[jakester]

Hi all,

I recently had a loft converted into an extra bedroom. I have had 3 double power sockets installed and these were connected to a fused box (13amps) that was previously used for an immersion heater that was removed and no longer needed. I tested the new sockets using a bedside lamp that i plugged in to each socket and it worked fine. However my builder tried to plug in a transformer for his power tools and as he did this the sockets tripped in the fuse box....... so it seems a lamp works but anything requiring more power trips the box.

Any help with this problem will be hugely appreciated.

Many thanks

 

[andy]

whats the rating of the MCB?

 

[smokeyJoe]

I don't think that you've got a problem.
Isolating transformers like the one you describe can have a huge initial current as the field builds up in the transformer core.
Try plugging it in then switching on the socket several times. You'll probably find that it doesn't happen every time as it depends on the point of the voltage waveform that the switch closes.
I've done the same thing on a bench feeding several computers with irate software engineers...
I suspect that in normal circumstances you're not going to be using appliances with large starting currents in your new bedroom (induction motors, isolating transformers etc) so it's probably best to leave the existing MCB as is, and enjoy the protection it gives.

 

[smokeyJoe]

Thinking further on this, the best test is probably to try a high-power non-inductive load like an electric kettle or fan heater. If it can power one of these without tripping, then I wouldn't worry.

 

[BJS_Spark]

Isolating transformers like the one you describe can have a huge initial current as the field builds up in the transformer core.

This is very true. I have poped out C16 mcb's at work on isolating transformers and then reset and then on a second attempt they are Ok.

 

[jakester]

Many Thanks to all who replied to my query, I will try the kettle or fan heater and see how I get on. Thanks again.

 

[jakester]

Thanks guys...

tried kettle and fan heater at same time and no tripping so thanks for the advice...

cheers.

 

[pantaiema]

Magnetizing Current Inrushcould be several times of full load.

Pantaiema