Breaker Tripping under unusual circumstance...

[westward10]

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[martinwood333]

Hi Martin - if you've an extension lead that might save your back

Right you are!

Also, can you move your PC and plug it into a downstairs switched socket on the ring circuit supplied by the 32A MCB to the right of the 16A one? Then do your x 10 switch on test. Take a picture of the socket you use.

Done this method, and no tripping at all on the downstairs 32A circuit. I think it's pretty definitive the 16A breaker may be to blame?

What switching are the sockets ? are they single or double pole

If there is a staggered opening of the switch contacts (live and neutral of the socket)and they do not break at the same time,its possible the Rcd sees this as a imbalance with the type of load being switched

This, I'm not sure about. I'll have to have a look. I see how that would make sense. Good shout!

Have you tried inserting the power cable/plug as a power on method before trying the switch, or only after using the switch has tripped the breaker. I ask this because (at least some of) the large inrush current will charge capacitors in the PSU which may have built up some charge from power ups that have tripped the breaker by the time you resort to unplugging and re plugging. I have also been told in the past that inrush curent can vary due to the point in the a.c. mains cycle when the circuit is made.

The arc damage you see on the plug pins will only get worse, especially if used to make/break a large inductive load. The plug should be replaced, and any sockets it has been used in should be checked for similar damage.

That's a good point. Usually whenever it's tripped I resort to my plug-in-while-the-socket-is-on method, or as of recent it's the only method I'll use as I'm not comfortable risking it tripping. It makes an audible POP sometimes when it happens, coming from either socket or PSU - can't really tell, but it's not a good sound.

It'll trip after my PC has been off for a good while, but not attempted it by using the switch immediately after the PC has been powered up and shut down, in quick enough succession that there is still charge in the PSU. I guess if it didn't trip, then it would signify in-rush is the definite cause?

Yeah the newly discovered damage is concerning me, and has really made me want to take care of this pretty urgently after putting it off for so long. Just found out my father-in-law knows a certified electrician. I've asked him to see if he'll be able to come round and witness it for himself and see what he makes of it aswell.

The whole fact that the upstairs sockets are on a 16A Type B breaker, whilst downstairs and kitchen sockets are on 32A Type 1 breakers, has me a tad confused. Obviously will need to confirm the wiring is of the suitable gauge before making any changes in that regard.

For sure though, I'll mention I've been in touch with you good folks and that I've attempted the diagnosis methods you've all mentioned, aswell as the potential causes.

 

[westward10]

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[SparkyChick]

The pop you here is the arc at the moment the plug pins make contact with the socket contacts. It results in the visible flash you mentioned in an earlier post and it's what causes the pitting in the plug pins (or the switch contacts).

It may be sensible to split the load up somewhat, but don't do it with switched extension leads as I found they have a tendancy for the contacts to weld together (this is how I staggered the in-rush... until the switch contacts fused).

 

[marconi]

One could suggest increasing the MCB supplying the socket to a 20A one provided that the wiring and its method of installation allow. But as Jim90 said in #6 I suspect you will still have occasional problems.

I reckon the robust solution is to provide a 32A MCB protected sockets circuit to the first floor. At the same time you can have an adequate number of sockets installed to dispense with the socket strips. The problem is high peaky inrush current - there are some big capacitors in the 850PSU for smoothing, filtering and active power factor correction. If you want to continue with surge protection MK do a double socket but they are not cheap. If it was me I would not bother with SP - the electronic components inside them lose their efficacy over time as they quench transients; in the case of MK one has to change a cartridge to renew the SP capability but if I remember correctly there is no indication of their state of decay to decide when it has to be done. Perhaps just insure your computers instead and unplug them during episodes of lightning.

So, time to call an electrician methinks.

SMPSU current waveform:

Tutorial-Pwer Meter Calibration - Yokogawa Test & Measurement Corporation - https://www.yokogawa.com/ymi/tutorial/tm-tutorial_wt_03.htm

Corsair850PSU:

RM Series™ RM850 — 850 Watt 80 PLUS® Gold Certified Fully Modular PSU - http://www.corsair.com/en-gb/rm-series-rm850-80-plus-gold-certified-power-supply