MCB tripping once on power up

[slip.cougan]

My study is upstairs on a single B16 MCB.
The room contains all our IT equipment.

I had to power down the system recently to get some other electrical work done.

We noticed that the MCB will trip once when power is re-applied. Provided that the MCB is switchwd back on in a timely manner, it will be perfectly fine. I can only assume due to all the IT related equipment in the Study with all the switch mode power supplies this initial surge is causing the MCB to trip. Once all the devices have a bit of charge then the MCB operates as expected.

When the room is operating it only consumes about 80-150W according to my Shelly Pro EM-50

Is a type B MCB the wrong type for this spur?

 

[Jurassicspark]

Most likely not.

A problem somewhere in the circuit causing the mcb to trip. Further investigation needed.

 

[JohnD]

If you get a switch-on surge, switch on the devices one at a time.

I've seen this on electronic devices.

Are you sure there is nothing else on the circuit?

I note you say it is an MCB, not an RCD or RCBO that trips.

 

[slip.cougan]

There is only one double socket in the room. The right socket has a homeplug adapter fitted to provide network to another location in the house. The left socket feeds an eight way surge protected extension. That is pretty hard to get to, due to all the other crap in the Study.
As a test, I switched off the left socket. Went and made a brew. Came back, turned on the socket and the MCB tripped.

Turned off the socket again, left it, turned back on, MCB, tripped but resetting quickly it stays on.

Talking to my Spark, he suggested that the Type B needs to be replaced with a Type C.

All the MCB's in the CU are protected with an 80A RCD. The CU is a Wylex fitted about 10 years ago.

 

[JohnD]

If you get a switch-on surge, switch on the devices one at a time.

I've seen this on electronic devices.

Have you rejected this suggestion?

 

[Murdochcat]

All the MCB's in the CU are protected with an 80A RCD. The CU is a Wylex fitted about 10 years ago.

That’s a daft configuration to say the least

One issue and you lose the lot

I would recommend you save up for RCBO board with SPD

 

[slip.cougan]

Have you rejected this suggestion?

Nope,

Just been having a chat with the Spark on WhatsApp as I know this can be overcome. We have sites at work that contain racks of network gear and this is not a thing. I was simply asking if there is a technical way to overcome this. I'd rather not have to crawl round on my hands and knees unplugging stuff.

 

[Murdochcat]

Nope,

Just been having a chat with the Spark on WhatsApp as I know this can be overcome. We have sites at work that contain racks of network gear and this is not a thing. I was simply asking if there is a technical way to overcome this. I'd rather not have to crawl round on my hands and knees unplugging stuff.

Not sure I agree with “not a thing”

Inrush currents DO trip MCB’s - seen it many times

 

[slip.cougan]

That’s a daft configuration to say the least

One issue and you lose the lot

I would recommend you save up for RCBO board with SPD

That seems like a reasonable response.

Lights are not on the RCD, Shower has separate RCD. The CU was replaced just before we bought the house. We've had the system checked a couple of times and only comments were it's outdated.

 

[JohnD]

Nope,

Just been having a chat with the Spark on WhatsApp as I know this can be overcome. We have sites at work that contain racks of network gear and this is not a thing. I was simply asking if there is a technical way to overcome this. I'd rather not have to crawl round on my hands and knees unplugging stuff.

A technical way is to have a timed startup mechanism, with delays, but I think pressing buttons one at a time would be cheaper for you.

You might also consider a multiway adaptor with switches, mounted in an accessible position.

 

[slip.cougan]

A technical way is to have a timed startup mechanism, with delays, but I think pressing buttons one at a time would be cheaper for you.

You might also consider a multiway adaptor with switches, mounted in an accessible position.

So, simply replace my eight way extension, with one with switched outlets? OK thanks.

 

[Murdochcat]

That seems like a reasonable response.

Lights are not on the RCD, Shower has separate RCD. The CU was replaced just before we bought the house. We've had the system checked a couple of times and only comments were it's outdated.

Your CU dates from around 2000 to 2007 IIRC

 

[Robin0577]

A technical way is to have a timed startup mechanism, with delays, but I think pressing buttons one at a time would be cheaper for you.

Yes, that's how the IT professionals do it in server rooms and suchlike, for precisely the reason of preventing nuisance tripping due to start-up surges. However, as John has already implied, such things are expensive...

10 Way 13A Sequential Start Vertical Illuminated Main Switch 13A Plug PDU - Olson Direct

Part No. 3273/13 • Power distribution unit for vertical mounting in 19" panels with illuminated on/off switch and ten 13A UK sockets. When the panel is switched on the first two sockets energise followed by pairs of sockets at 1 second intervals• A robust mild steel construction with Anthracite...

olsondirect.co.uk