New CU. Post installation questions.

[CESC]

I've had a new dual RCD CU fitted and I have a few questions about the installation.

• The MCBs are labelled incorrectly.

• Some of the neutral cables don't share the same slot number as their corresponding lives.

• I have a 10mm SWA running to my summer house. He's added an earth rod at that end, which I guess is no bad thing. However, at the house end, he's used a 1.5mm earth from the gland to the CU

• I have two radio linked smoke alarms. They're both on the same RCD

• The load balancing seems all wrong. I have a 45amp shower, cooker, kitchen ring and some lights and smoke alarms all on one RCD. The other RCD only has bedroom ring, central heating controls, and lights on it

Am I being too sensitive or does this sound like a poor job?

Many thanks for any answers here.

 

[Taylortwocities]

Umm, some small sins there.

From your list
The MCBs are labelled incorrectly.

They should state what they control and a schedule should be adjacent to the CU saying what each MCB controls. This should be the same at the schedule on the BS7671 INSTALLATION CERTIFICATE. (You did get one, didn't you?)
You should also have a Building Regulations Completion Certificate. This is a legal requirement.

Some of the neutral cables don't share the same slot number as their corresponding lives.
Well, they should. Its best practise. Not a capital offence.

I have a 10mm SWA running to my summer house. He's added an earth rod at that end, which I guess is no bad thing. However, at the house end, he's used a 1.5mm earth from the gland to the CU

That bit of wire is just providing an earth protection to the sheath of the SWA. Size depends on the value of the protective device but in general 1.5mm is too small for that circuit. I would want to see 4 or 6mm.

I have two radio linked smoke alarms. They're both on the same RCD
Not really a problem, your alarms will bleep if the power fails. Hopefully they share the same circuit as a regularly used lighting circuit?

The load balancing seems all wrong. I have a 45amp shower, cooker, kitchen ring and some lights and smoke alarms all on one RCD. The other RCD only has bedroom ring, central heating controls, and lights on it.

In designing split load dual RCD CUs, the general idea is to split the circuits so the downstairs sockets are on a different RCD to the downstairs lights. So half the house does not become powerless if there's a fault.
Would expect to see the cooker and shower on separate halves.
Post a picture of the CU with the cover on, and off, we like pictures!

 

[EFLImpudence]

You should also have a Building Regulations Completion Certificate.

Just a small point, but important difference - it's a Compliance Certificate.

 

[Taylortwocities]

Correct

Deliberate mistake to check you are paying attention

 

[Bluehair]

• I have a 10mm SWA running to my summer house. He's added an earth rod at that end, which I guess is no bad thing. However, at the house end, he's used a 1.5mm earth from the gland to the CU

Adding the earth rod seems to be a pointless exercise!

 

[Taylortwocities]

• I have a 10mm SWA running to my summer house. He's added an earth rod at that end, which I guess is no bad thing. However, at the house end, he's used a 1.5mm earth from the gland to the CU

Adding the earth rod seems to be a pointless exercise!

Why do you say that?

Perhaps he has one of those supplies where the DNO does not allow you to export the earth from the house to somewhere outside the equipotential zone.
Perhaps he has earthy exposed metalwork in the remote building (exposed-conductive-parts/water pipes etc).

 

[EFLImpudence]

 

[Bluehair]

Why do you say that?

Perhaps he has one of those supplies where the DNO does not allow you to export the earth from the house to somewhere outside the equipotential zone.
Perhaps he has earthy exposed metalwork in the remote building (exposed-conductive-parts/water pipes etc).

I was thinking that there would now be two RCDs in series.

 

[CESC]

Excellent replies, thanks all.

A few points for him to address then.

He's put the kitchen lights on the same side as the kitchen ring.
He hasn't provided an installation cert yet, presumably waiting for payment.
No building regs cert yet either, although I guess that can take a few days if he's only just registered the job.

He's NIC registered (I checked) so he should know better.

 

[ban-all-sheds]

I was thinking that there would now be two RCDs in series.

If there is one in the summerhouse CU then there will be two in series no matter what earthing system is used there...

 

[Bluehair]

I was thinking that there would now be two RCDs in series.

If there is one in the summerhouse CU then there will be two in series no matter what earthing system is used there...

And would you consider that to be a badly designed installation?

 

[bernardgreen]

Adding the earth rod seems to be a pointless exercise!

Not pointless, essential if the summer house is supplied as TT to avoid exportting the PME "earth" of the house.

 

[AndyPRK]

He's put the kitchen lights on the same side as the kitchen ring.

I try to avoid that. Not good.

 

[Bluehair]

Adding the earth rod seems to be a pointless exercise!

Not pointless, essential if the summer house is supplied as TT to avoid exportting the PME "earth" of the house.

I totally agree that there may be a reason for not exporting the earth.

But putting two RCDs in series (with the suggestion that they are both 30mA ones) when the summerhouse is powered by SWA suggests a lack of thought has gone into the CU swap. Incorrectly labelling the MCBs says enough about the quality of the work.

 

[Spark123]

Has the SWA armour been disconnected from the earthing at the summer house (and insulated)?
What size MCB is feeding it?
What is your main supply type, if you don't know please can you upload a pic of the service head (before the meter)?