Type 'A' RCD test results

[Michaelwgroves]

I just installed my first type 'A' RCD. When I tested it, I was amazed by the disconnection time. It was 148ms @ 1IΔn. Okay this is less than the required 300ms, and I know I take the 5IΔn for the report, but even so, this seems high to me.
Is this correct for Type A RCD, they are slower to respond than Type AC ?

 

[westward10]

Is it a Hager device.

 

[Michaelwgroves]

Is it a Hager device.

Yes it is, I'm intrigued..............

 

[westward10]

Have a read of this.
https://hager.com/uk/support/regulations-18th-edition/updated-rccb-testing

 

[Michaelwgroves]

Have a read of this.
https://hager.com/uk/support/regulations-18th-edition/updated-rccb-testing

Well that's a bit of a faff, is this just relative to Hager, or all Type A testing?
I assume new MFT's will have a variable option available, or will 50ma become the norm?

 

[Baddegg]

I use a lot of fusebox stuff and you get use to the times when testing but I have noticed when install the type A the times are slightly higher than Ac’s....

 

[Risteard]

I have found that typically Hager Type A RCDs (I haven't installed Type AC in years) have a slower operating time when tested on the Type AC setting than when tested on the Type A setting. I haven't been able to establish a good explanation for this.

 

[westward10]

Well that's a bit of a faff, is this just relative to Hager, or all Type A testing?
I assume new MFT's will have a variable option available, or will 50ma become the norm?

Not sure if it is unique to Hager but I think the issue is resolved on newer devices.

 

[Michaelwgroves]

Do I need a new MFT, I have a Megger MFT1711 ?

 

[pc1966]

I have found that typically Hager Type A RCDs (I haven't installed Type AC in years) have a slower operating time when tested on the Type AC setting than when tested on the Type A setting. I haven't been able to establish a good explanation for this.

I think that may be fairly common.

I tested some 'type AC' RCD FCUs with type A testing to see what would happen and in one phase/polarity they tripped faster and at lower current than expected going on 0.5*In in (from memory) 12ms or so, but slower other polarity slower but still meeting the 1*In times around the 140ms time. On type AC testing they were around the 28ms both phases.

I have no idea how universal that is as I just to see what might happen with some older kit that has not been updated to type A for the rectified style of load they feed.

 

[HappyHippyDad]

I just installed my first type 'A' RCD. When I tested it, I was amazed by the disconnection time. It was 148ms @ 1IΔn. Okay this is less than the required 300ms, and I know I take the 5IΔn for the report, but even so, this seems high to me.
Is this correct for Type A RCD, they are slower to respond than Type AC ?

From the replies it sounds like you have your answer, however I have noticed that 'sometimes' RCD's react differently depending on if you test them, i.e. actually at the RCD or if you have tested at a socket, switch or light. Where did you test this one Jeremy? Oops I mean Michael ?

 

[Michaelwgroves]

I actually tested from socket, when I go back and retest, I'll do it properly this time from RCD according to Hager instructions (Thanks Westwood10) . Be interesting to see how this differs from socket.

 

[HappyHippyDad]

Have a read of this.
https://hager.com/uk/support/regulations-18th-edition/updated-rccb-testing

Well that was interesting. Is that actually saying that it is incorrect to test a x5 on the 30mA setting (i.e. 150mA) and saying that we should be testing a 30mA RCD on the 300mA setting in order to make sure it is tripping within 40mS at x 5?

 

[westward10]

Hager devices are manufactured to disconnect within 40ms with a test current of 250ma, this is obviously above the ×5 we are accustomed to testing at but is inline with EN61008.
Regulation 643.8 does not specify a precise ×5 test current, it states ×5 or above which takes into account this 250ma. Personally to me if it trips within requirements at ×5 then it is fine.

 

[Ian1981]

For your information

 

[Michaelwgroves]

For your information

That's good to know, looks like I must have got old stock.

 

[Ian1981]

That's good to know, looks like I must have got old stock.

I think there’s still a load out there to be installed yet.

 

[AJshep]

The early Hager guidance of testing their A type RCDs was a bit of a cop out in my opinion. Westwood sums it up in his post above.
Never understood why everyone else could make a 30mA type A RCD trip at 30ms at 150mA but Hager couldn't.

At least they seem to have brought their devices inline with everyone else now.