RCD Types

EMartin2 · 2 Aug 2006

ON the small works certification cert there is a box for the RCD BS No and type, when RCD testing there are 2 selections to choose from: General and special (time delayed) is this what the box pertains to?
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lynda, moderator

moved as posted in wrong forum

Spark123 · 2 Aug 2006

I believe it refers to Type as in:
A = Protection against AC earth fault currents containing pulsating DC components
B = Protection against DC earth fault currents
AC = Protection against AC earth fault currents
S = Delayed

AC are the most popular type with type A being used for special applications.
It may be worth a call to the NICEIC to confirm?

dtrangmar · 4 Mar 2007

Inline with the incomer switch in my house, installed by the previous owner, is an RCD/ELCB that states it is BS842:1965 ELCB 60 Amp Type D. I can't find this BS Spec (without paying) so to continue the question on RCD types, does anyone know what defines a "Type D"? Partial information I have found suggests it's an industrial RCD/ELCB. If it's 3 phase it's a wrong install I guess. Regards, Daniel

Spark123 · 4 Mar 2007

Sounds like a voltage operated ELCB, if so these are no longer recognised by the IEE regs and is advisable to have them replaced asap. Just to double check can you post a photo? If not, can you post what is written on the front of the device?

Adam_151 · 4 Mar 2007

That standard does indeed seem to refer to a voltage operated device: http://standards.mackido.com/bs/bs-standards24_view_7197.html and as said above, no longer recognised by current revision of BS7671 (not since the 15th came out in the 1980s IIRC) and is due for replacement

securespark · 4 Mar 2007

Spark123 said:
AC are the most popular type with type A being used for special applications.

Aren't MEM RCD's (AD100HE) Type A, having a functional earth connection?

Spark123 · 4 Mar 2007

Just found a pic with a voltage operated ELCB //www.diynot.com/forums/viewtopic.php?t=78663

Spark123 · 4 Mar 2007

securespark said:
Spark123 said:

AC are the most popular type with type A being used for special applications.

Click to expand...

Aren't MEM RCD's (AD100HE) Type A, having a functional earth connection?

Probably, type A will function on both AC and DC pulse whereas an AC RCD can be locked up with DC. Don't know if the functional earth has much to do with the type though.

The LHS has the little picture below the BSEN no which is an AC, the RHS has the little picture below the BS no which is type A.

securespark · 4 Mar 2007

I got this little gem from a technical guy at MEM:

The Sensitivity results at 0º& 180ºpoint on wave equate to 10-millisecond time differential for a perfect rms profile.

dtrangmar · 4 Mar 2007

Thanks for the prompt responses and hopefully you can see the image below if I've followed scripting correctly.

Otherwise there's not much detail on the device:

BS842 Voltage Operated Earth Leakage Circuit Breaker, 60 Amp, 200/250v 50 Hz Type D.

Made by the now defunct / merged Ottermill of Hungerford.

Best regards,

Daniel

Adam_151 · 4 Mar 2007

securespark said:
I got this little gem from a technical guy at MEM:

The Sensitivity results at 0º& 180ºpoint on wave equate to 10-millisecond time differential for a perfect rms profile.

But where do you measure from? I assume by that then that they pick a set point on the waeform to test from for both tests (I assume one of the two 'zero-crossing' points), I kinda assumed that it was always a zero crossing just before the particular half cycle being tested to negate this effect.

(I'm told that the 0/180 switch actually only applies a half wave fault [by means of bypassing one of two diodes in reverse series], rather than as I originally thought, just selecting which half cycle to start the fault on)

JohnD · 5 Mar 2007

dtrangmar said:
BS842 Voltage Operated Earth Leakage Circuit Breaker, 60 Amp, 200/250v 50 Hz Type D.
Daniel

It is obsolete, no longer considered safe, and needs replacing.Do you know what kind of earthing your installation has? Do you have an oldish overhead supply?

If you can post a pic of the incoming service head next to your meter, that will help.

p.s. Did you remove a cover from it? If those live terminals are exposed as shown in your pic, they are very dangerous.

securespark · 5 Mar 2007

VO ELCB's deleted from the 15th Ed. in 1985.

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RCD Types

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