Can a 30mA RCD be used as the sole means of fault protection for a TT System?

[gap30]

Hi all, went to a job today to price up an shower install, it was a TT so as i was leaving i decided to do a quick check on the main earthing conductor as i could not see earth rod pit outside house, i had a look inside db and could only see 2 x 10mm earths which i assumed are gas/water.

Quickly isolated installation and went across earth bar and incoming L/N and did Ze got 102.4 ohms, it had a 30mA rcd incomer, could not see a main earth as it was only a quote did not want to get too involved, also did an RCD auto test, all the times were fine and did a Zs at a socket under DB and got reading of 105 ohms.

I am 99% sure there is no earthing conductor, is the RCD adequate? the way i see this if the RCD fails there is no means of fault protection, gonna check the regs in a bit but wanted some second opinions

 

[Risteard]

Perhaps one of the 10mm^2 green/yellows is the Earthing conductor?

 

[Darkwood]

Its probably using the gas and water pipes as an earth but it should be rodded, also i assume their is mcb protection as your thread title suggests sole means of protection if it has mcb's then your title is misleading but understand what you are wanting to know, so yes an earth rod will be required if TT system, consider the plumber coming in and taking off the gas/water bonding like they usually do :Oo

 

[gap30]

Quite possible but did not want to start stripping out the earth bar on a quote, maybe i could put on quote needs to be verified at time of install

 

[gap30]

Its probably using the gas and water pipes as an earth but it should be rodded, also i assume their is mcb protection as your thread title suggests sole means of protection if it has mcb's then your title is misleading but understand what you are wanting to know, so yes an earth rod will be required if TT system, consider the plumber coming in and taking off the gas/water bonding like they usually do :Oo

yes mcb's sorry should have stated that but yes thats worrying me with earths, i am ASSUMING they are gas/water

 

[Darkwood]

Quite possible but did not want to start stripping out the earth bar on a quote, maybe i could put on quote needs to be verified at time of install

The situe you have would be to quote for installing a rod and explain if you find one during the works then you will reduce the quote by x-amount

 

[gap30]

The situe you have would be to quote for installing a rod and explain if you find one during the works then you will reduce the quote by x-amount

Could not see any evidence of rod, cables come in above front door (terraced housing)

 

[trev]

I'd quote for the work you have been asked to quote for and add a paragraph stating "that you have reason to believe there is no proper earth facility although this has to be proven. If the work proves necessary then the additional cost will be £x"
The first thing you need to do is an EFLI test

 

[needasparks]

How are you able to quote without knowing the earthing supply of what you will be working on ?
From your question it sounds like your prepared to do this work without correcting it.

 

[gap30]

How are you able to quote without knowing the earthing supply of what you will be working on ?
From your question it sounds like your prepared to do this work without correcting it.

If that was the case i wouldnt have spent the last couple of hours speaking to sparks/checking my onsite guide and posting on an electricians forum

 

[gap30]

I'd quote for the work you have been asked to quote for and add a paragraph stating "that you have reason to believe there is no proper earth facility although this has to be proven. If the work proves necessary then the additional cost will be £x"
The first thing you need to do is an EFLI test

As i said i did a quick test and go 102.4 ohms without disconnecting any earths i know its not much but it was just to give me a general idea,i am going to speak further with client

 

[Darkwood]

Also i would have double checked as with any job that gas and water bonding is present, doing this you would have seen if it was looped or not and would have hinted to what both 10mm were, just because the board has 2 x 10mm dosn't mean they are actually connected to where you assume. if the plumbing has been altered your price will be out as you have a duty to ensure gas/water is bonded if required. Saving 5mins looking at the job will one day cost you alot or leave the job unsafe.

 

[gap30]

Also i would have double checked as with any job that gas and water bonding is present, doing this you would have seen if it was looped or not and would have hinted to what both 10mm were, just because the board has 2 x 10mm dosn't mean they are actually connected to where you assume. if the plumbing has been altered your price will be out as you have a duty to ensure gas/water is bonded if required. Saving 5mins looking at the job will one day cost you alot or leave the job unsafe.

Yes good call that

 

[gap30]

To be honest 4 sparks had been to quote and the guy said i was the only one who had queried this and got test gear out, i should have double checked 10mm earths on gas/water

 

[Steve_P]

I was always taught that the first thing you do on a quote, while the customer is boiling the kettle is find out where the incomming supplies are and where the earth rod is hiding.

As someone said, add the cost of a rod and bonding in with a proviso that it'll be knocked off as and when it's found.