How important is the isolation cable?

We've recently gone back to Virgin, this time with a 1Gbit service. Until 2021, we had the 100Mbit service that was installed in August 2019, via a completely new cable from the street box to our house. (FWIW this street box is about four doors down, so pretty close.)

When we quit Virgin last time around, I just left all the cables in place, including the coax from the wall socket. I had extended this by around 5 metres. Installation this time was therefore just a matter of plugging this into the new router.

But Virgin's also supplied a new "isolation" coax cable with what appears to be a large ferrite piece near the end. Does this actually matter? Speedtest is showing around 850Mbits over wifi, but that might be a wifi speed limitation. I'm unable to check via ethernet at the moment.

Edited by lulubonkers (Sat 04-Nov-23 14:54:55)

Best to use it unless you're a fan of 60v DC coming into the home and along the cabling 😊

I don't understand what you mean.

From Googling this, it appears the isolation component of the cable works as both a fuse and signal conditioner (and maybe EM noise suppression for other household devices....?)..

I've managed to insert the new isolator cable into the coax run to the router, so at least it's now in place. But it was working fine before this. SamKnowns reported speeds of 1,100Mbits to the router, even if the most I can get over wifi to the router is the aforementioned 850Mbits (via 802.11ax).

I very strongly suspect that the Virgin wall socket in the house has a built in isolator, because this was a relatively recent brand new install by the Virgin Media engineers back in 2019. This would explain why my previous Virgin router I used didn't require an isolation cable (none was supplied and that entire installation – from running cable to the house, to plugging in the router inside the house, had been carried out by Virgin engineers).

I think Virgin provided the isolator cable as a kind of backup in case the house didn't have one in the wall socket (e.g. it was an older install).

That is correct. The older VM installs used an isolator that looked like a rectangular block of metal. Mine is screwed to a floor joist just on the other side of the wall from the Omnibox. I don't have a wall socket, only a loose cable, The newer Quickstart push on cables come with the inline isolator as a precaution in case the existing wiring does not have one for some reason.

OK thanks. I'm guessing having two inline, which I almost certain do, doesn't cause any problems? What's actually inside these things? Is it full-on microcircuitry or just a few components like diodes etc.?

In reply to a post by Adduxi:

The newer Quickstart push on cables come with the inline isolator as a precaution in case the existing wiring does not have one for some reason.

In 2019 I wasn't offered Quickstart as they knew my place had existing wiring and they wanted to change it out. The technician removed the old "NTL" branded wall plate and put a new Virgin plate on, which includes what looks like your picture with an F-series screw connector on the outside. Then the cable to the Hub is simple.

As on the VM community forums when people ask about buying replacements themselves, the answer is pay VM £25 for them to solve properly.

There is a good reason. Frequency sharing. VM re-uses the frequency spectrum already occupied by Freeview TV Broadcasts, DAB digital radio & more recently 4/5G mobile phone services. Any ingress into their coax cables from these sources will disrupt VMs services, not only for that customer but possibly for the entire section supplied from the street cabinet they are connected to. This could lead to numerous unnecessary fault callouts & investigation work to find the source of the ingress. Hence they use specialised triple screened coaxial. The connectors also can cause issues if incorrectly fitted (micro reflections etc).

OK thanks.

I'm still unsure if the wall box has an isolator built-in, and it's essentially inaccessible, so I can't take off the face plate to have a look. So I've kept the isolator inline. Alas, I had to hack this to work with the extension cable I fitted a few years ago. Initially I fitted it back-to-front in the middle of the isolator cables, by accident. But I realised I could just attach the isolator component of the cable to the wall socket itself, and then run the extension from the end of the isolator. In other words, the isolator is installed more or less as Virgin request.

I can't help wondering if, in light of what you said, I've spent the last 24 hours scrambling everybody's TV, phone and internet who are nearby by running the router first without the isolator, and then with it in reverse.... Anyway, it's fixed now. Nobody on local FB groups has been moaning about any problems.

Edited by lulubonkers (Sun 05-Nov-23 13:36:14)

In reply to a post by lulubonkers:

Anyway, it's fixed now. Nobody on local FB groups has been moaning about any problems.

Think of it as an insurance policy. 😁

There's something very similar to that white "blob" that's inside the internal box on my 2018 install. The internal box in the picture below looks like this one in my house.

https://community.virginmedia.com/t5/image/serverpag...

Every time I've had a router sent they have included the same cable you've pictured, although I've always just used the original wiring from 2018. I've had Virgin Media around a couple of times (usually for intermittent faults and they have never said there is anything wrong with the wiring, but does make me wonder if that cable is indeed needed then or not). The last person who came a couple of weeks ago said the co-ax I had made up by the original installer is better quality (clearly a lot thicker) than the cheap ones that come with the Hubs.

Edited by gary333 (Sun 05-Nov-23 19:23:43)

In reply to a post by gary333:

https://community.virginmedia.com/t5/image/serverpag...

Glad to see this image is helpful for people - it's from my living room back when we had VM installed in August 2019... we've thankfully fixed the wallpaper!