On 29/03/2021 12:45, Roger Hayter wrote:
On 29 Mar 2021 at 10:15:39 BST, ""Brian Gaff \" Sofa\)"
wrote:

Which reminded me, why is it that a breaker of any type often seems, maybe
through never having been tripped for years can take too long to trip when
it finally does have a fault to protect against which can often mean a whole
fitting needs to be replaced due to overheating. Is it just build up of crud
or whatever, and should one say every few months manually trip these one at
a time to make sure they keep healthy?

Brian

It is normally printed on the front of them that they should be tested
periodically. But you are not alone in not seeing that!


I think Brian might be referring to how MCBs (and RCBOs) perform with
over current rather than how RCDs (and RCBOs) perform with an imbalance.
Testing how breakers perform with stable, over & short-circuit
currents requires special kit. I'd be interested to know if even Adam
carries it routinely.

--
Robin
reply-to address is (intended to be) valid