Hello all,

I am studying to be an electrician but outside of the classroom I have little experience.

A friend has bought a house and during the buying process had an eicr with unsatisfactory result.

Reading the report it shows the ring and shower circuit to have high earth loop impedance.

I ran the test myself today and the earth loop impedance on the ring and radial are around 40 ohms, which is what the eicr also shows.

I have checked the wiring of all the sockets and all seem to be terminated correctly.

r1, rn and r2 for the ring all seem fine.

According to the report the Ze is also fine.


What could be causing this?

I suspect a problem with one of the other circuits, would I be going down the right alley with that assumption?

Thanks,

Nick
 
Welcome to the forum. Can you add some further information..
What type of system is it?
What is the Ze?
What results did you get for r1, rn, r2 & R1+R2?
 
How many ohms are there in a 'fine'?

What are the readings for L-N loop impedance? What type of test did you use, low current or high current?


Sent from my iPad using Tapatalk
 
It's a tn-s, Ze on the eicr is 0.3.

R1 0.14, rn 0.14 r2 0.22. I ran out of time and didn't take r1 + r2 of the ring (it's not on eicr) I did no testing on radial, shower or other circuits.

From the eicr

shower earth loop impedance 42.3
ring 43 (confirmed with my meter today)
radial 42
 
It's a tn-s, Ze on the eicr is 0.3.

R1 0.14, rn 0.14 r2 0.22. I ran out of time and didn't take r1 + r2 of the ring (it's not on eicr) I did no testing on radial, shower or other circuits.

From the eicr

shower earth loop impedance 42.3
ring 43 (confirmed with my meter today)
radial 42

Are these circuits on the same RCD and if so are there other circuits on this RCD?
 
Are these circuits on the same RCD and if so are there other circuits on this RCD?
see where you're thinking. had similar where the excessive reading was caused by internal "resistance" of a RCD. one way to confirm would be to take readingss by this method on hi current test.

High current Zs test with RCD.jpg

diagram by courtesy of richard burns.
 
not necessarily. in the event of a fault, due to the higher current generated, the RCD impedance would probably be negated. also, there's the get-out 1667 value where a RCD is installed on the circuit/s.
 
Thank you.

So if by calculation I get an acceptable Zs (and also an acceptable one using the method described above) and the rcd trip times are < 40ms (which they are on the eicr) it would be acceptable to leave the rcd and installation as is (being safe)? putting those values of 40+ down as a quirk of rcd design

nick
 
Hi Andy,

i did did not measure those, the eicr has the cooker at 0.43 and the central heating at 1.44.

the eicr has the radial at 0.83, however I recorded the radial at 42 so unsure if the electrician doing the eicr did the radial, central heating and cooker by calc.
 
Hi Andy,

i did did not measure those, the eicr has the cooker at 0.43 and the central heating at 1.44.

the eicr has the radial at 0.83, however I recorded the radial at 42 so unsure if the electrician doing the eicr did the radial, central heating and cooker by calc.
I would check the Zs values of the other circuits on the same RCD to confirm the thinking.
 
Best EV Chargers by Electrical2Go! The official electric vehicle charger supplier.

OFFICIAL SPONSORS

Electrical Goods - Electrical Tools - Brand Names Electrician Courses Green Electrical Goods PCB Way Electrical Goods - Electrical Tools - Brand Names Pushfit Wire Connectors Electric Underfloor Heating Electrician Courses
These Official Forum Sponsors May Provide Discounts to Regular Forum Members - If you would like to sponsor us then CLICK HERE and post a thread with who you are, and we'll send you some stats etc

Advert

YOUR Unread Posts

Daily, weekly or monthly email

Thread starter

Joined
Location
South Wales

Thread Information

Title
High earth loop impedance
Prefix
N/A
Forum
UK Electrical Forum
Start date
Last reply date
Replies
19
Unsolved
--

Advert

Thread statistics

Created
Nickj,
Last reply from
Midwest,
Replies
19
Views
17,245

Advert

Back
Top