RCD a but slow. Time for a change?

[Electron]

I tested a customers BS4293 MEM 100A, 30mA RCD, which is about 25 years old, after it tripped overnight. The trip time at x 1 was 207.2, 78 and 54.2 ms at 0 deg. and 68.6 ms at 180 deg. I know that the limit is 200 ms, so one reading was slightly over, which is why I repeated the test. At x 5 it tripped at 50 ms at 0 deg. and 41.5 ms at 180 deg. So, again both over the limit of 40 ms. No trip at x 1/2.
Do these results mean I have to change the RCD? Or is there any tollerance? If so, can only get used identical replacement from the internet. Or should I change it to a RCD to BS EN 61008-1, like a Wylex 100A 2 Pole 30mA RCD?

 

[Octopus]

300 ms for 4293 rcds

 

[Ian1981]

300 ms for 4293 rcds

No its 200ms for 1x test for bs 4293 rcds

 

[Octopus]

No its 200ms for 1x test for bs 4293 rcds

Yup , got that wrong !

 

[Ian1981]

Yup , got that wrong !

It’s okay, I forgive you

 

[Andy78]

If the RCD was tested with no interfering background leakage from connected circuits, then yes, it's failed the requirements of BS7671 and its product standard and needs replacing.

 

[westward10]

It is unusual for a 4293 device to trip and then fail under test with a meter. What range of MEM is it.

 

[PEG]

Be handy to see the same tests with nowt connected,circuit wise

 

[Strima]

I wonder if it had been tested every three months for the last 25 years?

 

[buzzlightyear]

Yup , got that wrong

me thinks so, back of the class you go .

 

[Octopus]

Are these some of the types that you can’t rely on tests conducted directly at the rcd terminals and need a couple of feet of cable?

 

[buzzlightyear]

When testing BS 4293 type RCDs the testing method is the same as normal. @1/2xIΔn on both + and - phases, the RCD should not trip within 2s. The RCD must operate within 200mS @1xIΔn on both + and - phases (Note this is shorter than the BS EN 61008 RCDs we are familiar with). On 30mA RCDs @5xIΔn on both + and - phases, the RCD should trip within 40ms.
If it's a BS4293 S type (time-delay) RCDs the testing method is a little different, first you need to select the RCD time-delay test mode and perform 1/2xIΔn on both + and - phases, the RCD should not trip within 2s, as normal. Followed by 1xIΔn on both + and - phases, there is a 200ms time-delay and 200ms fault time i.e. the RCD should trip within 201-400ms@1xIΔn. Most testers don't allow testing at 5xIΔn in this mode, so it is inhibited automatically, the result is not required anyway even if the test is performed.
BS 4293 RCDs have since been replaced by the BS EN 61008 types.

 

[123]

@buzzlightyear I have a feeling you copied and pasted that from somewhere, can't for the life of me think why

 

[buzzlightyear]

I have a feeling you copied and pasted that from somewhere, can't for the life of me think why

it amazing what you can do with one finger.or two.

 

[buzzlightyear]

Type Test Current (IΔn) mA Maximum tripping time ms
BS EN 61008 X 1 ≤300*
BS 4293 X 1 ≤200
SRCD X 1 ≤200
All types for Additional Protection ≤30mA X 5 ≤40
Type S X 1 130-500 this should keep the op, happy. copy and put in the onside guide .

 

[Electron]

It is unusual for a 4293 device to trip and then fail under test with a meter. What range of MEM is it.

Does this help?

 

[Electron]

It is unusual for a 4293 device to trip and then fail under test with a meter. What range of MEM is it.

Does this help?

I wonder if it had been tested every three months for the last 25 years?

No. I always say to customers "Can I assume that you test the RCD's every three months?" They look at me as if they have broken the law!
Does anyone ever check the RCD? I only ever do it when someone pays me!

 

[westward10]

The only replacement you will get for that is from the used market, don't try to doctor in another non compatible device.

 

[Midwest]

Its a long shot, but you could try contacting Eaton to see if they have a compatible equivalent, looks like a MEM Memera 2000 CU?

 

[Deleted member 26818]

Looks like it’s going to be a new CU.