Hub 3 tripping electrics

[mike_babb]

Hi,

Last night one of the rcd fuses on my panel kept tripping out.  if i reset it it would then trip out again about 5-10 minutes later.  After a process of elimination it turns out to be the Virgin Hub 3, if that is unplugged the electrics don't trip. Anyone have knowledge of this happening before?  I am not an IT expert, so go easy on me!

[goslow]

Did you try the temporary connection via the RHS RCD and did the RHS RCD trip out in the same way as the LHS RCD once the coax cable to the hub was plugged in?

Do you have an isolator fitted to the incoming VM cable at some point before it is distributed around the home (or alternatively an isolator on each VM piece of equipment if you don't have a single central one)?

Sounds like you might have some kind of ground loop issue going on whereby your electrical installation is being partly grounded by the VM coax cable.

Beware when you are plugging/unplugging the VM coax connectors. You might possibly get a little electrical 'tickle' from the connector.

[mike_babb]

OK, I've done a bit more testing. If I run an extension reel from the loft socket which is fed from the rhs trip after approx 5 mins when the green light goes out on the router the left hand rcd trips, the same one that always trips. Again, it only trips when the coax cable is connected to the router. The router was powered up for over 24 hours without the coax cable and there were no issues (apart from no internet, of course!). 

The Virgin engineer is coming tomorrow between 4 & 7. Do you think he would put some sort of meter on the coax to see if there is an issue? I can't see how it can be with the electrics in the house, but I'm not an expert.

Thanks again for your advice.

Mike

[mike_babb]

Looking at the router, the threaded input that the coax screws onto is slightly loose.  I wonder if that is faulty inside and causing a short of some sort. 

[goslow]

The main thing the VM tech can probably do for you is to check that there is an isolator in place covering each coax connection supplying a piece of VM equipment in the home. How much more help the VM tech can/will offer may well depend on the abilities of the individual person that turns up and the time they have available. They are often time-limited for each job and this could be the kind of job that requires some faffing about to work out where the fault is.

If the VM tech comes up up with a solution (and a plausible explanation) that fixes the problem, then all well and good. If not, then your next route would be via an electrician. An electrician should have the necessary kit such as a clamp meter to measure the earth leakage on your installation under different working conditions. S/he should also be able to carry out insulation resistance tests on the circuits covered by the LHS RCD and should be able to carry out a ramp test on the LHS RCD to make sure it is tripping at the correct limit and is not over-sensitive to tripping.

[ALF28]

GROUND LOOP?- this may be causing the RCD  breaker to  trip.

Usually a galvanic isolator is included in the VM coax signal line close to the hub, this prevents ground loops occuring.

This also protects any earth loops to neigbouring houses.

Check to see if you have one, it is an inline device in the white cable, marked galvanic isolator. I do have one connected in my  white cable  next to my hub and there can also be attenuators in some cases which drop the signal voltage supply. The galvanic isolator may have been removed?

also see previous post-

Galvanic isolator - Virgin Media Community - 4585031

broadband galvanic isolator - Bing images

10kHz_150MHz_Antenna_Galvanic_Isolator_manual (herostechnology.co.uk)

TV can also have this problems-see, my tv signal cable also has an inline device in the cable.

coax tripping breaker | Electrician Talk

alf28

[ALF28]

240v 13a  mains power socket - testing for faults-

I have a socket tester by LAP, bought from screwfix for a few pounds, it plugs into the socket and can detect up to 14 faults.

For example earth/neutral reverse could result in rcd tripping.

I had an issue myself of RCD tripping which was caused by a central heating wall thermostat, where the plumber had used the earth wire as a neutral connection, solved by replacing the 2 core cable with a 3 core plus earth. As earth wires are bare the ends need insualting in the socket to prevent touching other connections.

Also insects can cause tripping if they get inside of plugs or sockets, sometimes trips breakers, rare but I have had this.

My toaster and kettle often trip the rcd. Water and damp can cause trips or breadcrums in the toaster if not cleaned out.

Remenber  allways to switch off/unplug electrical equipment, and isolate circuit at the breaker before inspecting sockets/electrical items. Other causes of tripping can be damage to cables. It is  always best to use a qualified electrician.

The RCD trip is to prevent electrocution detecting leakage to earth usually 30milliamps, and the MCB and plug fuses  trips/blow  on overload/short ciricuit, disconnecting the supply to limit damage and fire.

alf28

[mike_babb]

OK, in my testing I must have overlooked isolating front drive lights/sockets. I thought I had but TBH, when it started tripping when the coax is connected to router I assumed the issue was Virgin related. Once I isolated the front drive lights & sockets the router has worked ok without tripping out. When I overide the time switch on the front drive lights the left rcd trips (but oddly not the rcd protecting only the front drive lights & sockets). I'm guessing with all the rain we've had some water has got into the lights and is causing a short, although quite how that is connected to the coax cable tripping the rcd when the router finishes booting up I have no idea.  I think i need a decent sparks! 

Thanks for your advice everyone.  👍