PowerWall Isolation - Smart Meter Replacement

[Cuban8]

Octopus is replacing both my L&G SMETS2 meters next week because of PW2 incompatibility and a failed gas meter. I will need to isolate the supply from my solar array and PW2 - both are routed via a garage consumer unit to my main meter box with an armoured buried cable.

Both the solar array and the PW2 have isolation switches in the cabling to the garage consumer unit. With respect to the PW2, if I just isolate the supply to the sub-consumer unit will this be sufficient for a meter change or should I go through the whole procedure of turning off the PW2 (ie; isolate PV; turn off battery, and trip CBs in Gateway 2)? Clearly, I do not want to electrocute the installer nor do I wish to damage either the PW2 or Gateway2.

 

[ACarneiro]

Why do you need to isolate the PW and solar array?
If you have a Gateway, once the mains is cut, the house will be isolated from the grid and there will be no back feed so the meter will be safe to work on.

 

[Glan gluaisne]

There needs to be a physically locked-off isolation switch - you cannot ever rely on something internal isolating a supply, as faults can, and do, occur. It's the reason so much emphasis is placed on proper dead-testing before starting any work on live circuits.

As an idea as to how important this is, the procedure is to test the meter on a proving unit to be confident it works, then use the meter (NEVER a voltstik or similar) to check that the circuit is dead, then recheck the meter with the proving unit to be sure it's not failed when doing the check.

 

[ACarneiro]

Well, there are breakers in the Gateway.
There should also be cutout switches on each PW and on the DC supply to the inverter.
Just turn them all off. I did when I had my smart meter fitted and it all just came back online no problems.

 

[MrBadger]

In advance, may be worth asking them to put a whole house isolation switch in. It goes between the meter and the henley block (sounds like you don't have one) or consumer unit. So totally isolates both poles of the third party meter/main fuse from any home owned electrics.

One may have helped in this circumstance probably allowing, if the PW had backup facility and procedures allowed, for the house to remain live whilst meter changed.

 

[Cuban8]

My meter box looks like this:

The armoured cable comes in from my detached garage consumer unit to a sub consumer box with two 63amp RCBs: one supplying the house and the other the garage sub unit. The wiring to the right is from the adjacent PW2. Thinking about it a bit more, turning off the main isolation switch in the meter box along with the Gateway 2 switch should provide 2 points of isolation, or am I getting this completely wrong?

 

[MrBadger]

Looks like you have a whole house isolation switch. The red levered switch coming inline of the tails out of the meter.

I would say, if procedure allowed, isolate there and job done.

I'm glad you are not showing more to the right though...

 

[Cuban8]

Thanks. Sorry, but you have lost me. The B50 and B63 RCBs were replaced when the PW2 was put in as they were deemed non complaint. The armoured cable and meter box consumer unit are the remedial actions that were taken when I found out that the electrician working for the developer on my new build had connected an 7.2kW EV charger to the existing garage 32 amp ring main.

 

[98dizzard]

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Thanks. Sorry, but you have lost me. The B50 and B63 RCBs were replaced when the PW2 was put in as they were deemed non complaint. The armoured cable and meter box consumer unit are the remedial actions that were taken when I found out that the electrician working for the developer on my new build had connected an 7.2kW EV charger to the existing garage 32 amp ring main.

The box after the meter with Wylex on it should isolate the whole house, including the powerwall. The house might be running off emergency power, but it should be completely safe to work on the meter.

 

[Cuban8]

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The box after the meter with Wylex on it should isolate the whole house, including the powerwall. The house might be running off emergency power, but it should be completely safe to work on the meter.

Thanks. I will just let the installer do his own thing. No doubt he will shout if he is not happy.

 

[ACarneiro]

Hopefully he will shout if he’s not happy...

 

[Glan gluaisne]

As above, that DP isolator is fine for making things safe, can even be locked off if needed. No need for anything else, as the meter fitter will just turn off all the loads, isolate the demand side with that DP isolator, then remove the main fuse, before doing a dead check at the meter tails and swapping the meter over for the new one.

 

[Cuban8]

Ok - cunning plan failed. The installer insisted that he had to follow Octopus’ instructions which required a replacement isolation switch despite the fact that it had only been changed by an Octopus’ meter installer 17 months ago. He also replaced the gas regular when he fitted my new gas meter. The gas meter failed to commission and I was asked by Octopus to start the initiation process again 2 days later.