Testing Zs the scary way

[ADS]

Hi,

Just wondering, does anyone, (or has anyone) tested Zs this way:

A radial socket circuit protected by a 20A 30mA RCBO - keeps tripping the RCBO

on Zs test.

You haven't got a no-trip tester so you :-

Isolate the main switch and remove cover from board.

Open RCBO for socket circuit.

At furthest socket, short together Line and CPC - easiest way is to use an

adapted plug top.

Close main switch and test - one probe on the incomming side of circuit

RCBO, one probe on outgoing side of circuit RCBO (RCBO still open, obviously)

Take reading - job done.

Any takers?

Oh Yeh, Don't forget to remove the plug top bad day explode

 

[Badger]

Hi,Just wondering, does anyone, (or has anyone) tested Zs this way:

A radial socket circuit protected by a 20A 30mA RCBO - keeps tripping the RCBO

on Zs test.

You haven't got a no-trip tester so you :-

Isolate the main switch and remove cover from board.

Open RCBO for socket circuit.

At furthest socket, short together Line and CPC - easiest way is to use an

adapted plug top.

Close main switch and test - one probe on the incomming side of circuit

RCBO, one probe on outgoing side of circuit RCBO (RCBO still open, obviously)

Take reading - job done.

Any takers?

Oh Yeh, Don't forget to remove the plug top bad day explode

or you could just change it into a mcbtemporary

 

[septiclecky]

Hi,Just wondering, does anyone, (or has anyone) tested Zs this way:

A radial socket circuit protected by a 20A 30mA RCBO - keeps tripping the RCBO

on Zs test.

You haven't got a no-trip tester so you :-

Isolate the main switch and remove cover from board.

Open RCBO for socket circuit.

At furthest socket, short together Line and CPC - easiest way is to use an

adapted plug top.

Close main switch and test - one probe on the incomming side of circuit

RCBO, one probe on outgoing side of circuit RCBO (RCBO still open, obviously)

Take reading - job done.

Any takers?

Oh Yeh, Don't forget to remove the plug top bad day explode

Tie your horse up at the hitching post and watch your spurs.

If it is a PIR put it down as a limitation or calculate it?

 

[ADS]

If it is a PIR put it down as a limitation or calculate it?

Yeh, I appreciate that you can always calculate, but I was wondering if

anyone used this method - I mean, technically, there's nothing wrong with it

but our 2391 lecturer nearly fell off his chair when I described it to him

 

[ianmacd]

What about all those class I accessories that are now at 230V?

 

[ADS]

What about all those class I accessories that are now at 230V?

I don't get what you mean - you're only applying the normal test current to the circuit (for Zs measurement) that you would do normally, your just cancelling out the breaker.

As long as you don't leave the plug top in when you re-energise the circuit

 

[ianmacd]

How do you test Zs without the circuit being live?

 

[ADS]

How do you test Zs without the circuit being live?

It becomes live when you connect the probes either side of the breaker - that completes the circuit and gives the reading - same as doing it the conventional way

 

[ianmacd]

OK but would be bad if the curcuit was energised with your plug still in. Have you got a 1A fuse or similar in the plug?

 

[spinlondon]

I used to work with someone, who had made up a number of plugs that were linked out.

These were used to find the breakers. Plug them in, and the breaker would trip simples.

 

[ianmacd]

I used to work with someone, who had made up a number of plugs that were linked out.These were used to find the breakers. Plug them in, and the breaker would trip simples.

Novel replacment for a fuse finder.

 

[ADS]

OK but would be bad if the curcuit was energised with your plug still in. Have you got a 1A fuse or similar in the plug?

Wouldn't be much good in this instance - doesn't a Zs test push 20A down the circuit?

I'm not making this up or trying to trick anyone - this test procedure is

actually described in one of the I&T books:

Christopher Kitcher's 'Practical Guide to Inspection, Testing and Certification'

Page 85

http://www.whsmith.co.uk/CatalogAndSearch/ProductDetails.aspx?productID=9781856176071#

I just wondered if anyone did it in the real world - I haven't but I'm not

saying I wouldn't.

 

[ianmacd]

Would have thought most modern MFT's or RCD testers had a no trip option now though.

 

[Andy™]

Hi,Just wondering, does anyone, (or has anyone) tested Zs this way:

A radial socket circuit protected by a 20A 30mA RCBO - keeps tripping the RCBO

on Zs test.

You haven't got a no-trip tester so you :-

Isolate the main switch and remove cover from board.

Open RCBO for socket circuit.

At furthest socket, short together Line and CPC - easiest way is to use an

adapted plug top.

Close main switch and test - one probe on the incomming side of circuit

RCBO, one probe on outgoing side of circuit RCBO (RCBO still open, obviously)

Take reading - job done.

Any takers?

Oh Yeh, Don't forget to remove the plug top bad day explode

thats not a bad idea. for one or 2 circuit, probably quicker than swapping to non RCD

 

[ADS]

[quote name='Andy

 

[Andy™]

live - earth short

 

[steptoe]

Ive done this,

and it doesnt send 230v down the earth any longer than a normal test.

I also have a LNE shorted plug top for the old method 2 test.

 

[ADS]

[quote name='Andy

 

[ADS]

In addition, you can use the same method on your split/17th Ed boards.

Open your RCD and the MCB for the circuit that you're testing.

Place one probe on the outgoing side of the circuit MCB and the other probe on the RCD (or main) incommer - same result

 

[Andy™]

In addition, you can use the same method on your split/17th Ed boards.Open your RCD and the MCB for the circuit that you're testing.

Place one probe on the outgoing side of the circuit MCB and the other probe on the RCD (or main) incommer - same result

dont forget to short L to E at end of circuit

and dont forget to make sure main switch is turned off, or you may get a false reading through the neutral