Is My Tester Faulty Or Me

[rins]

hi guys

recently upgraded a consumer unit usual tests performed and satisfactory apart from the rcd auto test, this would fail on kitchen and upstairs sockets, now its never failed before so oviously ive been lucky with upgrades no dodgy wiring anywhere.

anyways as this was an empty property i knew i could pop back once id caught up my work i moved onto my next job which was a kitchen rewire with a cu upgrade again, finished this and again tests were fine until rcd auto test on sockets. i have a metrel mi3000 it is due for calibration next month.

so i then tried switching off all mcbs and testing the rcd only, earth probe to earth bar and live and neutral probes into loadside of rcd press test and again x1 read >300ms.

anyone use this tester i know i will get resistance through the coiled plug in tester so thats why i tried testing at the board and providing ive done it correctly then i presume my tester is at fault or a cheaper solution is that iam at fault haha any help guys would be appreciated thank you

 

[Andy™]

ever considered that the RCD may be faulty?

 

[Apache]

maybe just try it on an RCD in isolation

 

[Revved Up Sparky]

i then tried switching off all mcbs and testing the rcd only, earth probe to earth bar and live and neutral probes into loadside of rcd press test and again x1 read >300ms.

The neutrals would still be in circuit. It might be worth disconnecting the main neutral between the load side of the RCD and the neutral bar and doing the test again.

(+1 to Apache's comment.)

Of course one other thing you could do is try and borrow another RCD tester and do those tests again with both testers and compare the results.

 

[SPECIAL LOCATION]

Is this the ONLY RCD you have access to??????

What results do you get on a KNOWN GOOD RCD..

i.e. CU change = New equipment = Unproven items..!!

Do you not have a know good RCD for doing regular interim calibration checks on

between formal (annual / bi- annual) checks??

Don't forget RCDS should be tested with loads disconnected!

(sounds to me like you are rushing between jobs and not giving full attention to the actual job in hand..)

Do you ever not actual try energising an RCD to test it works BEFORE connecting it up to any final circuits?

The fault at the moment is the logic of your testing procedures..

TOO MANY UNKNOWS...

Its not rocket science to compare with another RCD..

whats more to the point...

NEW CU???

must have more than one RCD surely?

what test results does the other RCD give????? :C

 

[sb_89]

I normally test the rcd at a socket, but if you do test an rcd at the cu ( like it sounds that you are) i only test between live and earth ? No need to use 3 probes. Try just using the 2.

Testing at a socket is much easier - you only have to disconnect loads attached to a circuit, you don't have to disconnect circuits

 

[SLIPSHOD & SLAPDASH]

I normally test the rcd at a socket, but if you do test an rcd at the cu ( like it sounds that you are) i only test between live and earth ? No need to use 3 probes. Try just using the 2.

Testing at a socket is much easier - you only have to disconnect loads attached to a circuit, you don't have to disconnect circuits

What tester do you use that does not need a neutral . You are testing the Rcd not the wiring and not meant to test at an outlet

 

[sellers]

are you testing on auto at 30mA it may be set to 15mA therefore not tripping on 1x

 

[batty]

Could be low batteries or the make of RCD have had problems with MEM RCD's not testing at the mains.

 

[steptoe]

does it trip on manual?

as sellers said, check the settings, you may have changed it inadvertently,

I had a session once where I had changed mine to DC and couldnt for the life of me work out why 3 brand new RCDs were all faulty, different manufacturers too.

 

[sb_89]

What tester do you use that does not need a neutral . You are testing the Rcd not the wiring and not meant to test at an outlet

I'm using a megger 1502, why would the tester need a neutral to test the rcd ? You only need to create a leakage of 30 ma live to earth to create an balance.

Also best practice only says to disconnect loads, a circuit isn't a load as it doesn't pull any current, it's fine to test an outlet.

 

[Doc Hudson]

I'm using a megger 1502, why would the tester need a neutral to test the rcd ? You only need to create a leakage of 30 ma live to earth to create an balance.

Also best practice only says to disconnect loads, a circuit isn't a load as it doesn't pull any current, it's fine to test an outlet.

Actually it also says, tests should be made on the load side of the RCD as near as practicable to its point of installation. That is in the on site guide. So at a socket outlet would general not constitute 'as near as practicable to its point of installation'.

Doc H.

 

[sb_89]

Well Doc we have conflicting information, as I'm currently looking at an niceic testing and inspection guide and it clearly says ' the connection can be made at any convenient point in the circuit, such as a socket outlet or light fitting'

I know the niceic guides aren't related to bs7671 as such but they do promote good working practises.

 

[steptoe]

All "proper" guidance I have ever read in regards to testing RCD state at or as close to the RCD as possible.

 

[sb_89]

Give me one good solid reason why it would make 1 iota of difference where the rcd was tested from if the loads are disconnected.

Also I'm pretty sure the niceic guides are credible sources of information

 

[Doc Hudson]

Assuming you are referring to a booklet such as the NICEIC domestic periodic inspection and testing guide, I agree that it does indeed state that any convenient point such as a socket outlet may be used, whilst also offering the one site guide (probes on terminals method) suggestions as well. However from a convenience point of view I find being located as near to the RCD itself makes any reseting very quick and easy, that in conjunction with 11.1 from the on site guide suggesting as near to the RCD as possible and on a CU with multiple RCD's or RCBO's it can save a lot of walking around testing at the CU itself. Convenience, functionality and meeting industry recommended guidance all covered. It would be interesting to hear id Napit, Elecsa or anyone else has any differencing guidance for testing RCD's?

Doc H.

 

[sb_89]

I don't dispute that testing at the board is the easiest, I just dispute that you can't, or it is wrong to test at a socket. It really doesn't make any difference at all to the trip times.

Also you could read convenient as not having to disassemble the cu Doc. As always it's how the individual interpretes the regs.

 

[ProDave]

I don't dispute that testing at the board is the easiest, I just dispute that you can't, or it is wrong to test at a socket. It really doesn't make any difference at all to the trip times.

Also you could read convenient as not having to disassemble the cu Doc. As always it's how the individual interpretes the regs.

WHY do you ever test an RCD?As part of initial verification of a new install, or as part of an EICR in which case the CU has it's cover removed.

I'm struggling to think of a time when I might want to test an RCD without having the cover off the CU

 

[sb_89]

Regardless, as I read it, it's acceptable to test at a socket outlet.

 

[Andy™]

FWIW, i usually test the RCD from a socket.

reason being, if its fails to trip with the expected wiring / load conencted to it, then testing in isolation is a bit like throwing some water over an earth rod to get the reading lower. it may pass, but you know its not going to comply and be safe once you walk out the door

and most testers have auto test anyway, so just plug it in, go to board, flick back on 4 times, then go get results from tester