Odd test results on RCD Spur

[haptism]

Tested an RCD spur earlier with some odd results

Tested at x 1/2 (both waveforms) and no trip
x 1 (0 degrees = 28.5 ms), (180 degrees = 18.4 ms)
x 5 (0 degrees = 8.2 ms), (180 degrees = 40 ms)

S0 getting bang on 40ms at x5 on 180 waveform; i know its in limit but was expecting it to be (at least) as low as the x5 0 degrees result.

The supply is TNCS, the circuit has low Zs, testing carried out at rcd spur itself, with load side disconnected. Tried it with two different sets of leads and same result, the testers been recently calibrated.

What would you do in this situation ?? I realise the x5 result is within limits (just). Really im perplexed, if this result is due to the nature of the waveform, or if the RCD is iffy.

And to add to the mix im reading that x5 rcd tests are , strictly speaking only required where your max Zs values cannot be met.. e.g. TT installations.

 

[Pete999]

Tested an RCD spur earlier with some odd results

Tested at x 1/2 (both waveforms) and no trip
x 1 (0 degrees = 28.5 ms), (180 degrees = 18.4 ms)
x 5 (0 degrees = 8.2 ms), (180 degrees = 40 ms)

S0 getting bang on 40ms at x5 on 180 waveform; i know its in limit but was expecting it to be (at least) as low as the x5 0 degrees result.

The supply is TNCS, the circuit has low Zs, testing carried out at rcd spur itself, at load side with circuit disconnected. Tried it with two different sets of leads and same result, the testers been recently calibrated.

What would you do in this situation ?? I realise the x5 result is within limits (just). Really im perplexed, if this result is due to the nature of the waveform, or if the RCD is iffy.

And to add to the mix im reading that x5 rcd tests are , strictly speaking only required where your max Zs values cannot be met.. e.g. TT installations.

How many times did you carry out the tests? could be just a glitch

 

[haptism]

How many times did you carry out the tests? could be just a glitch

At least 4 times, twice with each set of leads

 

[Pete999]

At least 4 times, twice with each set of leads

Oh right thanks need to think again.

 

[diditrain]

Was there any load connected?

 

[haptism]

Was there any load connected?

No, load was disconnected

 

[diditrain]

Was it new or an old one with a sticky switch?

 

[haptism]

Was it new or an old one with a sticky switch?

Its a brand new one out the box,

 

[Ian1981]

5x rcd tests on 30mA rcd’s are for the circuits circuits requiring and covered by said rcd and require additional protection so must trip within 40mS @ 150mA regardless of what type of earthing arrangement is in place.

 

[haptism]

5x rcd tests on 30mA rcd’s are for the circuits circuits requiring and covered by said rcd and require additional protection so must trip within 40mS @ 150mA regardless of what type of earthing arrangement is in place.

Yeh additional protection against direct contact , x1 tripping times below 200ms would account for that where the circuit has a low enough ZS would it not ? I know the regs state x5 have to be within 40ms for TN systems too, but thats' backup to protect against a low high Zs scenario aint it

 

[static zap]

What band RCD ?

 

[haptism]

What band RCD ?

Gotta admit its a Toolstation jobbie, SafetySure brand

 

[Pete999]

What band RCD ?

Oh BRAND I did wonder

 

[static zap]

Oh BRAND I did wonder

Oops , Pink Floyd !

 

[haptism]

Oh Band, its a usual AC band/type