it is extremely difficult to answer a question to any electrical query if a person has not visited the site with the problem...it becomes a guessing game unless all aspects of the installation are given.
i have learnt from a wise man not to assume anything when it comes to electrical installations.
an example is the cap for the motor which got me started with this thread.
when i go to a site...for example to quote for a job...i have learnt to get all the info especially on industrial sites where the main supply transfomers are close to the main db and the ka rating could affect the size of cable required for the installation to motors...buzzbars for the control panel...etc...and i know you gona say thats standard practice...well is it ?
i have noticed on various sites i have been visiting...it doesnt seem to be the norm...in fact i am starting to wonder if the electrical inspectors who are signing over these installations are aware that the original design was in fact not done correctly...or upgrades have been done since the original installations was done...were there was a 500 kva transfomer and now there is a 1000 kva transfomer but the main db and control panels have not been upgraded only the main switch and supply cable....
we all know the answer to this kind of enquiry...but the change was done 5 years ago and its worked fine all this time...so my reply no problem find someone else to sign ove rthe COC and of course there will always be someone who will sign it over rather them than me...i plan on being around for another 20 years so i cant take the chance.
i am generalising..but speaking from an experience which happened recently...i have noticed that electricians are employed by the company who dont know the difference between a 2.5...5/6...10...15...25 kabreakers and when they are used in the DB...they also use contractors who pull the wool over their eyes because they can see the sparky working on the site is clueless...the owner of the company is unaware of what is happening in his factory because he thinks the electrician has all the qualifications as per his cv and also doesnt realise that he becomes responsible for the electrical installation and safety of employees on the site....suddenly there is an explosion on site and nothing trips except the 3200 amp mains...eeeeish now someone is in deep dwang...but who?