EFLI in 2391 land.

[SirKit Breaker]

Do it as described in GN3.......END OF.

Cheers..........Howard

 

[La Poste]

Unfortunately the method in GN3 is as vague as it is helpful.
I guess the bottom line is C and G are looking for safety awareness and anything you say to improve safety will tickle them pink.

Anyway I'm away to get p1ssed, I've had enough of this revision for one week.

 

[La Poste]

Here's another one:

"The installation forms part of a 230V, 50Hz TT system with a PFC of 1.3KA.
A 100ma RCD, which also serves as the main isolator, is installed in the consumer unit."

Describe the test procedure to determine the resistance of the installation earth electrode.

Book answer:

1. seek permission to isolate.
2. safely isolate supply and all circuit-breakers.
3. select an earth fault loop impedance tester, confirm calibration, condition and leads to GS38.
4. disconnect the earthing conductor from the main earthing terminal.
5. connect the instrument, earth lead to disconnected earthing conductor, neutral to outgoing neutral of main isolator and line to outgoing line of main isolator.
6. close main isolator.
7. check the instrument set to 200 Ohms and carry out the test and record the result.
8. Open main isolator and disconnect instrument in the reverse order.
9. reconnect the earthing conductor.

Now I am no expert but would this not trip the RCD which is incorporated in the main isolator?
I mean we are allowing current to flow from the line over to the earth, surely the RCD will see this as an imbalance between line and neutral and switch everything off.

Any thoughts?

Thanks.

 

[malcolmsanford]

As it seems to be a 3 lead test then I would imagine somewhere along the line that book is utilising the non-trip RCD method, though not sure what meter they are using when they say set to 200ohms.

 

[La Poste]

I always thought to test an earth electrode a high current test would have been the preferred option.

 

[malcolmsanford]

Well I would certainly use the hi test one.

 

[La Poste]

What do you mean the test one?

 

[telectrix]

malcolm, thet are going back to the megger LT5 which had a slider switch to select range. 20ohms or 200ohms. and i would agree that the no-trip should not be used for Ze. they state a pfc of over 1kA if that is pefc, then it must be a bloody long rod.

 

[malcolmsanford]

The normal hi test one

 

[malcolmsanford]

malcolm, thet are going back to the megger LT5 which had a slider switch to select range. 20ohms or 200ohms. and i would agree that the no-trip should not be used for Ze. they state a pfc of over 1kA if that is pefc, then it must be a bloody long rod.

Cheers Tel as you know I'm not a megger man

 

[telectrix]

nor a downlight man either, mate. LOL.

it's a stupid way to test anyway. you fit your leads to the terminals as they suggest, then switch on the isolator. which of your leads falls off first when you throw the switch?

 

[malcolmsanford]

In fairness Tel I have nothing against Megger, just not used them, I was brought up on Martindale and robin and I suppose that is what you get use it, put it this way if someone wanted to give me a megger I would not turn it down, I might need to come to you in a lesson on how to use it though mate:devilish:

But the dowlighters are a different thing mate .........................:banghead::cuss:

 

[telectrix]

if you can use a robin, you'll have no problems with the megger. it's so simple even i can use it ( and i don't mean as a door stop )

 

[brucelee]

Here's another one:

"The installation forms part of a 230V, 50Hz TT system with a PFC of 1.3KA.
A 100ma RCD, which also serves as the main isolator, is installed in the consumer unit."

Describe the test procedure to determine the resistance of the installation earth electrode.

Book answer:

1. seek permission to isolate.
2. safely isolate supply and all circuit-breakers.
3. select an earth fault loop impedance tester, confirm calibration, condition and leads to GS38.
4. disconnect the earthing conductor from the main earthing terminal.
5. connect the instrument, earth lead to disconnected earthing conductor, neutral to outgoing neutral of main isolator and line to outgoing line of main isolator.
6. close main isolator.
7. check the instrument set to 200 Ohms and carry out the test and record the result.
8. Open main isolator and disconnect instrument in the reverse order.
9. reconnect the earthing conductor.

Now I am no expert but would this not trip the RCD which is incorporated in the main isolator?
I mean we are allowing current to flow from the line over to the earth, surely the RCD will see this as an imbalance between line and neutral and switch everything off.

Any thoughts?

Thanks.

Hi mate the 100mA rcd which serves as a isolator also would be switched off and to carry out the test this would be done on the supply side with isolator/rcd off and all loads removed then disconnect earthing conductor

 

[JUD]

Hi mate the 100mA rcd which serves as a isolator also would be switched off and to carry out the test this would be done on the supply side with isolator/rcd off and all loads removed then disconnect earthing conductor

I think that's what's confusing everyone.

Whichever book the OP is getting these answers from is saying to carry it out on the load side of the main switch (for "safety" reasons).

I've never heard of it being done this way.