Earth Bonding - DIY

RE: Earth Bonding

Toodles — Thu, 04 May 2023 15:54:22 +0000

@transparent We are awaiting a call back from Virgin on the ridiculous as we have 3 handsets that will need powering (special equipment for hearing impaired user etc.) which in turn entails occupying a 13 amp socket and trailing wires. VM point out they will not work in a power cut so we will be requesting one of their equipments that connect to the hub but provide a connection at all times to cover us for emergencies. They are not aware that we have islanding powering -with apologies, in case anyone is interested, this is the gist of the VM message: Regards, Toodles.

On 21 June your current home phone service will stop working and be switched over to our fibre network. We will send you an adapter in the post which you’ll need to use to connect your home phone to your WiFi Hub so you can make and receive phone calls over our fibre network.

What you need to do

Keep an eye out for the adapter. It'll come with simple step-by-step instructions to help you get it set up. You’ll need to do this on or after 21 June.

Do you have any connected devices?

In the unlikely event there’s a power cut or a fibre network disruption, you won’t be able to make or receive calls and most connected devices (such as a burglar alarm linked to a control centre, a telecare device, or other phones connected to extension sockets) will be affected.
You’ll also need to contact your device provider and let them know about the switch to make sure they’re compatible with a fibre service.

If you rely on your landline for accessibility needs or don’t have a mobile to make an emergency call we’ll provide you with an emergency back up line so you’re always able to call emergency services.

RE: Earth Bonding

Transparent — Wed, 03 May 2023 19:41:25 +0000

I'm assuming that the 'change' is due to Virgin Media upgrading the network from FTTC (Fibre to the Cabinet) to FTTH (Fibre to the Home).

Copper phone wires supplying a home do have an earth reference point at the cabinet. That's the 1-metre high box along the street somewhere. But that earth isn't to provide safety for end users if you send mains 240v or a lightning strike down the wires! The copper is too thin to take that sort of current.

The earth reference acts to protect the equipment owned by OpenReach or whoever your supplier is.

Once the cable to the house is upgraded to fibre optic, it can no longer have any earth reference.
Your link now uses photons, not electrons!

Nor can it provide the 80v across the pair of copper wires which produces the 'ring tone'.

So two things have to be changed in the home.

1: Your broadband router gets changed to one with a fibre-optic link to the outside world.

2: Your 'landline phone' needs to receive power from the house electricity supply.

The latter is more complex than it first appears.
The telecomms regulations require that it must be possible to make a call from the house during a power-cut.
So the new phone also has a battery which keeps it 'live'.

None of this has any bearing on the earthing for the house.

If anything, it makes the situation simpler.
In the event of a nearby lightning strike, you no longer have a copper telephone wire connecting into the home.
The only earth which concerns you will therefore be the one associated with the mains electricity supply.

RE: Earth Bonding

Toodles — Thu, 27 Apr 2023 13:30:38 +0000

A further (possible?) complication is about to rear its’ ugly head here; Virgin Media have informed us our telephone service is about to be changed and we will be provided with ‘adaptors’ to connect our telephones to our wif-fi equipment. I think that the present system has an earth connection alongside the telecommunications signal cable from the nearby street side connection box. I don’t know how this new system will work but suspect we are going to have to provide a 240v. mains supply to plug into. Might this external cable from the street side connection box also carry an ‘earth’? Regards, Toodles.

RE: Earth Bonding

Toodles — Thu, 27 Apr 2023 12:18:31 +0000

@transparent Wot have I started (in my innocents, I might add!)?

RE: Earth Bonding

Transparent — Thu, 27 Apr 2023 11:30:06 +0000

Let's pause for a moment whilst I lay out some of the issues I'm wanting to see clarified:

1: We are in the early days of seeing widespread roll-out of numerous new energy technology products which are installed in a home:

Smart Meters
PV Solar panel inverterss
Heat Pumps
EV chargers
electricity storage batteries

If a house on a PME electricity feed installs more than one of these technologies, how may earth stakes would the home-owner expect to see?
I think the answer is 2, but that's what I want my DNO to clarify.

2: What's the situation if my Tesla Powerwall contains a double-pole isolation relay and a Neutral-earth bond relay, but my hybrid on/off-grid solar inverter does not?

Is the overall installation able to obtain consent from the DNO because the inverter's Neutral takes advantage of the N-E bond relay in the Powerwall?
And, if so, what's the situation if the Powerwall is faulty and has to be removed for a few days?

3: Since I have yet to learn of any heat pump site which fully complies with Building Regulations Part-L (heat).

What level confidence should the home-owner or Local Planning Authority have that the same installation complies with Part-P (electricity)?
If neither us consumers nor the LPA know enough to check these Building Regs notifications, why are we using taxes to pay for the service?

4: The IET guidance document we've been discussing here has a diagram which shows trips for mains appliances operating from the grid and others operating off-grid sharing the same consumer unit:

3840

How is it OK for an electrician to work inside that unit?

Haven't we just devalued the requirement for a consumer unit to have a double-pole disconnector labelled MAIN SWITCH in red?

RE: Earth Bonding

Transparent — Thu, 27 Apr 2023 08:58:49 +0000

the article isn't saying the earthing arrangement is always TN-S, I think it's saying the earthing arrangement becomes TN-S when the grid is down and the isolators and bond relay have done their stuff.

Erm... that's the point I'm making.

Earthing can't "become TN-S" unless there is a separate earth wire in the feed cable.

Perhaps the author is simply being too loose in terminology. Does he perhaps mean:

the earthing becomes TN-S if the feed is TT or TN-S
the earthing becomes TN-C if the feed is TN-C

"Becoming TN-S" implies that an earth wire suddenly appears in the feed for TN-S sites.

Either way, the phrase is confusing. We need to learn what the 'rules' are, and then come up with our own simple guideline...
... which I'm minded to be diagramatic in nature!

Let's look at this from the DNOs' viewpoint.

You only have to spend 5mins on this Forum to see that there is widespread failure to install renewable energy systems correctly.

To pick up just one technology, I have yet to read a description of a heat-pump site which actually complies with Building Regs Part-L (energy/heat).

Given this plethora of errors, how confident can we be that the installers have successfully implemented Part-P (electrical) in respect of the earthing arrangement?

RE: Earth Bonding

Toodles — Thu, 27 Apr 2023 07:59:49 +0000

@steevjo I intend to, untidy though it will be on the front of the house. There are various lengths of unused gas pipe under the floors going ‘nowhere’ - but at least they still have an earth bond! As the gas meter box disintegrated some years back and the flap was being held with a bamboo cane, I saw no reason to ask ‘someone’ (don’t know who that would be even) to replace repair the dilapidated box so it is now reduced to the back plate, piping, brackets and some heavy gauge earthing connections. A bushy plant will be grown in front of the remains of the box. Regards, Toodles.

RE: Earth Bonding

Steevjo — Thu, 27 Apr 2023 07:18:42 +0000

@toodles

3: A gas pipe is still regarded as a gas pipe if the meter is removed.

4: To maintain earth continuity between two gas pipes which were originally connected via a meter, an earth-link is installed.
As it connects to the incoming service pipe, it is not your property and may not be disturbed or removed.

Re your earth bonding. I think the answer is in @transparent’s first reply. Leave it in place.

RE: Earth Bonding

Steevjo — Wed, 26 Apr 2023 21:19:08 +0000

@transparent The diagram in the article isn't saying the earthing arrangement is always TN-S, I think it's saying the earthing arrangement becomes TN-S when the grid is down and the isolators and bond relay have done their stuff. When the grid is operating normally the earthing arrangement is as shown in the connected mode diagram and is TN-C-S.

When the grid is down it could be for lots of reasons - one of which is the overhead cables to my house have been disconnected by a tree falling on them. At that point there really isn't a feed belonging to the DNO.

RE: Earth Bonding

Transparent — Wed, 26 Apr 2023 19:51:55 +0000

Posted by: @transparent

↑

The earthing arrangement of most EESS in island mode, where the installation has a low voltage public supply connection, is therefore always TN-S.

My reading of this is that when the grid is down the island is operating in TN-S mode

Hmmm. That's not what the author is claiming.

You can't implement an earthing arrangement which is always TN-S (ie based on Separate Earth & Neutral), if the feed belonging to the DNO is TN-C (Combined).
The separate earth wire isn't present in a TN-C feeder cable.