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Message 1 of 14 (391 Views)

Superhub causing RCD to trip

Hi, my superhub is causing my electricity to keep tripping - would anyone be able to tell me if this is because the hub may be faulty or is it to do with my circuit? Many Thanks!
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Fibre optic
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Message 2 of 14 (374 Views)

Re: Superhub causing RCD to trip

Have you definitely isolated the cause of the RCD trip to the Superhub? If so I'd guess it's a faulty DC adapter and to be honest I'd ring Virgin and just ask them to change both the hub and adapter. They may wish to send an engineer to check everything, but if the hub has been in situ for a while without causing problems I doubt it's your circuit.

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Message 3 of 14 (352 Views)

Re: Superhub causing RCD to trip

That's great thanks. I've definitely isolated it to the hub. It's been working fine for 4 months which made me wonder if something is wrong with it. I'll contact Virgin and take it from there. Thanks again.
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Dialled in
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Message 4 of 14 (329 Views)

Re: Superhub causing RCD to trip

In that case I would be very careful.

tts possible that there a high leakage current from the mains input to the output of your power supply, in which case the output jack could have a dangerous voltage if you disconnect it from your router.

Alternatively, it could just be that your RCD is over sensitive. Does anything else trip it?


Hlc_4 wrote:
That's great thanks. I've definitely isolated it to the hub. It's been working fine for 4 months which made me wonder if something is wrong with it. I'll contact Virgin and take it from there. Thanks again.

 

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Rising star
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Message 5 of 14 (314 Views)

Re: Superhub causing RCD to trip

RCDs these days are very reliable and as it's probably a 30ma trip it would be tripping correctly. Essentially they measure the differential between live and neutral which leaks to earth. RCDs are very good, but unless you have a split box with two of them, when they trip they take out the whole house. I prefer RCBOs and have 10 in my house protecting all circuits, so if one bit of equipment trips the RCBO it only takes out one circuit, say downstairs ring main. All my computer equipment is on one RCBO.


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Forum Team
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Message 6 of 14 (249 Views)

Re: Superhub causing RCD to trip

Hi there Hlc_4,

 

Sorry to hear about this. :/

 

I've located your account and there does appear to be some power issues present via the equipment levels.

 

I've sent you a private message so that we can discuss potentially arranging an engineer visit for this.

 

Speak soon,

 

Nat_J


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Message 7 of 14 (187 Views)

Re: Superhub causing RCD to trip

Hi

 

A coupla things to consider...

 

My superhub has a mains step down adapter WITHOUT a metal earth pin, it's plastic.  So the leakage to earth and subsequent trip of an RCD is not possible.

The possibility of a leak thru to the secondary side is a real possibility and care should be taken when removing it. 

However there is no obvious path to Earth for any fault current to find, it is low voltage DC and anything higher would most likely fry the superhub, even allowing for ethernet cabling going into my PC which is earthed. Possible but highly unfeasible.

Therefore it may be the socket that the superhub plugs into that is causing the fault.

An RCD is set to trip at typically 30 milliamps for a period of 30 milliseconds, sometimes a filter on an extension socket can have an inrush of current and cause a trip. The current needed is about 7 watts.

Fixed items like a freezer or Microwave oven have lamps about twice that value, some LED lights are about that so I would definately get the Superhub replaced if VM are amenable, but would not accept that is the definitive answer.

It is difficult to isolate such a fault when there are things permanently connected and are difficult to isolate like clocks on cookers etc.

If in doubt please ask.

 

Rising star
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Message 8 of 14 (170 Views)

Re: Superhub causing RCD to trip

The N neutral line in AC mains is effectively earth. I know it seems strange but if you look at the HT pylons you will see mostly 7 wires, one small one at the top which is tied to earth and 3 on each side, these are two lots of three 3 phase connections. So where is the neutral line? There isn't one it's not needed. 


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Message 9 of 14 (143 Views)

Re: Superhub causing RCD to trip

Hi

The supply is a balanced 3 phase supply.  On step down there is a set of 3 windings/coils to the the lower voltage, and these are in a "star" pattern.  The centre point of the star has a cable taken from it to carry/return any out of balance load.  From this "NEUTRAL" point another tapping is taken and this becomes your Earth.  Some installations only have 2 wires taken and an 'earth' is created locally, using a rod into the ground.

Whatever you have;   the RCD has 2 windings of a few turns, (CW & CCW) creating a balanced magntic field, they cancel each other out.  When an imbalance occurs, some current not returning down the neutral line, then the out-of-balance magnetic field(s) trips the RCD via a trip wire.

My point is that there is no return path (it is a plastic pin from a plastic case) other than the neutral, so an out of balance cannot occur. 

However I do not exclude the remote possibilty of a DC current somehow leaking through and causing nuisance tripping without frying the superhub.

NB: I have, in my apprentice days, manged to light a tiny torch bulb from the voltage difference between the Neutral bar and Earth, it's about a volt and a half, and when the power is off any light can be a blessing.  Of course health and safety would currently frown on such a method.

Superuser
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Message 10 of 14 (134 Views)

Re: Superhub causing RCD to trip

Just a thought in addition to the above excellent advice.

Is the HUB plugged into a power strip?

Ive had a power strip go bad whereby anything plugged into one of the sockets caused the RCB to trip.

 


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