17th Edition Consumer Unit

[Wessex]

Good morning, this is my 1st time on here and I'm trying to understand a quote for electrical work I've been sent and so would be greatful of any constructive help.

The quote says "the property has no main earth" and "in addition the current consumer unit and water bond are not to 17th edition regulations"

I only had this house wired in around 2004 so shouldn't these be ok?

Am I been Naive?

Thanks

 

[1john]

Take a photo if the consumer unit you have now and post it here. Just because it was done in 2004 doesn't mean it was done correctly. Just because someone says it hasn't been done correctly doesn't make that statment true either. The 17th edition regulations were introduced in 2008.

 

[Wessex]

Thanks for the prompt reply, I'll do that next time I'm in the house, it maybe a couple of weeks as I work away.

 

[ericmark]

The compliance with 17th Edition is not a problem in it's self and it only means if you are having work done it may cost more as the new work needs to comply.

The lack of an earth is more serious. This will need correction ASAP. The earth system is decided by the supplier and there are three systems.
TT
TN-C-S
TN-S
The first uses and earth rod the second two use an earth supplied by the supplier. If you look at the paperwork supplied in 2004 you will see the type of earth marked down. I have seen where a house was re-wired and the electrician had phoned the DNO who had said the house should be TN-C-S and he had wired the house accordingly. Leaving an earth wire for the DNO to connect to. However where the guy from the supplier arrived the readings he got were not good enough to give a TN-C-S supply and so he did not connect the earth wire. Result was no earth connected yet both had done what they should. The time scale had resulted in the electrician no longer trading by time the supply was connected. However he did pay a visit and did fit an earth rod and RCD. Could something similar have happened to you?
Look at all your paperwork.

 

[ban-all-sheds]

The quote says "the property has no main earth"

If that is true it needs attending to as a matter of great urgency.

"in addition the current consumer unit...not to 17th edition regulations"

That is almost certainly true, but you are under no obligation to update it. What is the work you are having done? All that will need to be done to the 17th, so it may be that it would be cheaper overall to update the CU.

Or it may be that the electrician is trying to amplify the value of the job.

How many quotes have you had?

"water bond are not to 17th edition regulations"

It should be - nothing changed re that between the 16th & 17th, but who knows how good a job they did back in 2004? That can be sorted out at the same time as the main earth.

I only had this house wired in around 2004 so shouldn't these be ok?

Earthing and bonding should be - absolutely no question of it.

 

[ajrobb]

If "the property has no main earth", it might mean that it has a TT supply (rather than a TN supply with the earth going back to the substation). All circuits on a TT supply must be RCD protected. Some circuits might not be suitable for 30mA RCD circuit protection, so a TT supply can also use a 100mA time delay RCD S-type "Main switch" instead of an ordinary isolator. I think the idea of these is that a local earth connection cannot take the whole fault current, so an RCD is used to disconnect the service in case of a major fault. I hope this explains some terminology on the quote.

 

[ban-all-sheds]

If "the property has no main earth", it might mean that it has a TT supply (rather than a TN supply with the earth going back to the substation).

It still has a main earth - i.e. a main earthing terminal, a main earth conductor etc.

 

[ajrobb]

It still has a main earth - i.e. a main earthing terminal, a main earth conductor etc.

Excuse my ignorance, have I misunderstood? The OSG only shows main earthing terminals for TN-C-S and TN-S supplies. For TT supplies it just shows the CU's "installation earthing terminal".

 

[ban-all-sheds]

Lord knows why that is.

It didn't show it like that in the 16th OSG, or the EGTTBR which was current with the 16th. (Does anybody know what that shows now? I never bothered buying a new version).

But anyway - whether it's in the CU or external it is still, according to the definitions in Part 2 a main earthing terminal.

 

[ajrobb]

I think I can see a perverse kind of logic.

For a TT supply, the earth is not supplied from the mains. If only the supplier is allowed to put put stuff on the distribution board, the earth terminal needs to go elsewhere and the CU is convenient. Tenuous but...

Then again, my 1978 fuse box on TN-C-S used the CU's earth terminal for bonding gas and water supplies. This caused a problem when I had to upgrade the bonding conductors to in the new CU to 10mm². I was stuck with a 6mm² conductor from TN-C-S but had to use 10mm² into the CU.

 

[ban-all-sheds]

I think I can see a perverse kind of logic.

For a TT supply, the earth is not supplied from the mains. If only the supplier is allowed to put put stuff on the distribution board, the earth terminal needs to go elsewhere and the CU is convenient. Tenuous but...

Tenuous. And bogus.

Even if it's in the CU it's still the Main Earthing Terminal.

The highlighted words are not refering to the same thing, even though the letters are the same.

Then again, my 1978 fuse box on TN-C-S used the CU's earth terminal for bonding gas and water supplies. This caused a problem when I had to upgrade the bonding conductors to in the new CU to 10mm². I was stuck with a 6mm² conductor from TN-C-S but had to use 10mm² into the CU.

542.4.2....

 

[Risteard]

It still has a main earth - i.e. a main earthing terminal, a main earth conductor etc.

No such thing as a "main earth" or "main earth conductor". It is the earthing conductor.

 

[Taylortwocities]

Oh dear

I Predict a Riot

 

[mbga9pgf]

Oh dear

I Predict a Riot

Sounds like someone is trying to do over the OP if they have TT installed.

We had ours checked out the other day. Ze was 7 ohms, which was pretty good tbh as the ground was frozen solid

 

[ban-all-sheds]

Did they disconnect the main bonding to do the test?