Rig testing

[leccyman]

Hi Guys

I have built a rig in my shed to practice testing on. Ive got a couple of issues need resolving.

Set up:

Supply to shed via swa from house c/u. Protected by rcd.

Shed has a garage c/u with 40a 30ma rcd,20a and 6a breakers.

When trying to do an rcd ramp test it trips the rcd in the main house.

When testing zloop it also trips the house.

Due to these issues i am reluctant to even try iso test.

I understand i cant get a TRUE Ze as it is connected from the house c/u

Any suggestions

 

[sparkytim]

Hi GuysI have built a rig in my shed to practice testing on. Ive got a couple of issues need resolving.

Set up:

Supply to shed via swa from house c/u. Protected by rcd.

Shed has a garage c/u with 40a 30ma rcd,20a and 6a breakers.

When trying to do an rcd ramp test it trips the rcd in the main house.

When testing zloop it also trips the house.

Due to these issues i am reluctant to even try iso test.

I understand i cant get a TRUE Ze as it is connected from the house c/u

Any suggestions

Hi

To test the RCD in the shed with out tripping indoors connect Live probe to OUT Going L terminal and N+E probes to INCOMING N terminal on shed RCD.

Does your Meter have a "no trip" Loop test range?

If not then it WILL trip the RCD.

Another way to test the Zs is to put a L-E Short on at the end of line (Circuit turned off first of course)and then using LOOP Tester at the SUPPLY end connect the E probe to the MCB OUT GOING terminal (with it turned OFF) and the L probe from the INCOMING Live feed to the RCD or any other NON RCD protected Live terminal.

Your Meter will "bridge" the RCD and give a true Zs reading.

Same for PFC

 

[confused-fuse]

what is the swa connected to ? 6,10,16,20,32,40 mcb what supply is it ?? TT,TN/CS, what length to shed what v/d are you getting ?

 

[WarrenG]

By the sounds of it, you have no discrimination between the 2 RCD's?

If you have 2 RCD's rated at 30mA in series one or the other can trip out first, dependant on a number of things.

You will need to take the supply off the RCD in the house to get your true RCD readings for the shed.

For loop testing, use a non-trip / D-lok tester.

 

[leccyman]

Hi Confused-fuse

The swa is connected to the main breaker as per thread start info. The house is tncs and the shed is approx 25metres away.

 

[ADS]

Hi Leccyman,

Can you not put the SWA into an MCB on the non-RCD side of the board in the house CU.

Then you can test away in your shed to your hearts content.

 

[leccyman]

Thats a good idea ADS. I will have a look at that today.

 

[confused-fuse]

i would stick a rcbo on the none rcd side of cu that would stop the tripping as well .. what size is the swa cable 2/3 core is it clipped or underground ?.. i did a shed a few months back and the builder got the wrong size cable and tryed to wire it direct to the tails as it kept tripping the rcd side of cu .. silly builders...

 

[Zeespark]

Idiots like that need hanging, though I have seen an 'electrician' do that as well.

AndyGuinness

 

[sparkytim]

i would stick a rcbo on the none rcd side of cu that would stop the tripping as well .. what size is the swa cable 2/3 core is it clipped or underground ?.. i did a shed a few months back and the builder got the wrong size cable and tryed to wire it direct to the tails as it kept tripping the rcd side of cu .. silly builders...

Eh ?

Then the RCBO would trip as well.

Did You read the first Post?

This Guy has 2 RCDs in series and wants to test the Garage end RCD without tripping the Rcd indoors.

The way to do it has been posted but may be its a bit to complex as it involves testing with leads and not just plugging in to a socket.

 

[WarrenG]

By the sounds of it, you have no discrimination between the 2 RCD's?If you have 2 RCD's rated at 30mA in series one or the other can trip out first, dependant on a number of things.

You will need to take the supply off the RCD in the house to get your true RCD readings for the shed.

For loop testing, use a non-trip / D-lok tester.

Just checking to see if I can read my own post.......I think a few missed it?

 

[a1]

100mA Time delayed 'S' Type RCCB, house end.

 

[ADS]

There's no need to RCD the house end at all.

He wants to use it as a test rig, so he needs to be able to perform all tests in the shed, without having to worry about the house CU tripping.

 

[leccyman]

Guys, guys, guys, stop it now. Its sorted. Did as you suggested and moved to a side of the c/u without rcd. And i even managed to use the leads sparky tim and not plug in socket. On That note I also have an easy switch which does most of the testing at the press of a button but i have not even had it out the box yet as I want to learn how to use the LEADS first.

 

[sparkytim]

You have returned from the shed! :Welcome: BACK

Was getting a bit worried there LOL

Which tester do you have then?

 

[a1]

Which tester do you have then?

A Metrel MI 3125B Tester.

 

[sparkytim]

A Metrel MI 3125B Tester.

Thats good! did I miss a Post somewhere or is this Admin's superior ability to know what Test gear all us mortals have?

 

[a1]

Thats good! did I miss a Post somewhere or is this Admin's superior ability to know what Test gear all us mortals have?

http://www.talk.electricianforum.co.uk/showthread.php?t=10082

 

[sparkytim]

Ahh Haa

You have shattered the illusion now, just a simple case of observation i see.

ROTFWL

 

[leccyman]

Sparkytim. I have a Metrel 3125B with an easy switch which does most of the tetsing in a fraction of the time. Will be trying it out tomorrow i think(if I am brave enough lol)