Circuit breaker

After 35 years, does it actually move?


Regards


BOD

Given that the device is now obsolete and spares are probably not obtainable - I would not recommend operating it to check it's function until a replacement plan is in place.  


You don't say what the switch board supplies but if we assume that the loads are important then continuing to operate them via a device that probably cannot be repaired if it fails is asking for trouble.  Replacement will probably be problematic as the switch board may have to be modified if an mccb with the same form factor and method of connection cannot be found. 


It has a Castell key so I assume that it is part of a switching system.  Is there any other means of supplying the switch board if this mccb is out of commission - if not a planned replacement should be considered.


This situation is encountered all too often. The owners of such equipment really should considered what they would need to do in the event of a failure in any part of their supply system that is essential to their operation. 


Regards


Geoff Blackwell

Sound advice indeed Geoff! There is, as you rightly suspected, a generator feed in. The switchboard would require to be completely isolated to add or remove other protective devices as it comprises bare busbars immediately accessible on the removal of any cover section. The installation is in a large cold store and the device in the photo can be operated when ammonia is detected in the adjacent compressor plant room. I don’t know why this was done as there is a separate MCCB serving the MCC in the compressor plant room and the alarm output could have been connected to either end of that. As it stands, I backed out of running a test on the alarm as I feared the device would not re-set. This happened in another plant when the alarm activated on a real gas escape and the main MCCB would not reset. We were in danger of loosing hundreds of thousands of pounds of frozen goods so you can imagine the panic in trying to get things back on line. It is the same company so obviously they are not up for learning lessons!

LOL.


I get nervous about operating domestic main switches that have not been touched for thirty five years, knowing I have a spare on the van. 


Twice I have had millionaires refuse to pay for replacing domestic main switches in properties that they rent out the failed after being used for their intended purpose, because of course they were alright before I touched them.


Needless to say now have to use the services of another electrician.


Andy Betteridge

Failures occurring when operating switchgear during inspection & testing (I & T) are one of the perils of the work.  Many clients do not appreciate how long it might take to source replacements, particularly if the equipment is old.


I once operated the main intake protective device (ACB ) during a I & T in a large building society admin office - as the switch moved I heard a clatter which sounded like something had dropped off inside.   This was on a Sunday and the office need to be open on Monday!


Whatever it was the switch had jammed - panic ensued but after many attempts I managed to close it again.  I was waiting for a big bang but my luck was in!


I had to arrange for it to be replaced and this required isolation (by the DNO) from the supply transformer and fitting a replacement of a different type.  It took several days to source the replacement and to fit it.


The question of who is liable for any loss here would be difficult to resolve.  I did not have a particular disclaimer in my T & Cs but maybe it is something that should be considered.


Regards


Geoff Blackwell

Geoff


I have it written in to my terms and conditions sent to the client in advance of starting work on site.


We did an inspection on a very large installation where a 200A switch was installed in 1943 when the building was erected as a secret shadow factory for the DeHavilland aircraft company. The outside was heavily corroded and. I doubt if it was moved since installation. It was isolated for inspection and testing but it would not go back in. We borrowed a tin of WD40 from the site maintenance team an set about spaying the pivot points and prodding the springs and moving the parts with a screwdriver until it eventually went back in with a satisfactory clunk and no bang. Reported on the EICR as requiring replacement.

Resulting in a "satisfactory" or "unsatisfactory" John?


Regards


BOD

BOD


The site had both C1 and C2 defects so "Unsatisfactory ".