i am busy completing a project which involved and upgrade from 60 to 80 amps 3 phase.
i did my claculation and due to other considerations...worked out...that it would be in my best interest to install a 25mm x 4 core ecc cable...so i fit everything and wait for the supply authority to connect the main supply cable...shortly after the connection is completed...my customer confronts me about the size of the cable...because apparently according to the electrician who installed the supply cable a 16mm x 4 core...indicated to my customer that i had ripped them off because i had installed a 25mm cable and should have only installed a 16 mm cable which according to him is capable of carrying 60-100 amps and the 25 mm cable can carry 100-125 amps...i am still waiting for the calculations to backup his theory...
just something to note...we have a serious volt surge and drop issue on site...which has been reported to the supply authority on numerous occasion...they have increased the transfomer tap settings (which has caused even more headaches due to voltage surges)...i had a PQA connected to the supply for a week...because of the clearline trip connect 3 unit i installed...it keeps dropping out the contactor...the PQA indicates that the voltage varies from 179 volts to 254 volts...the span set on the trip connect 180-250...where do you stop opening up the span?
the reason i installed a trip connect unit was because the thieves keep stealing the main sub cable...and for some reason they always manage to cut the neutral first...and you know what happens on a 3 phase system...at least with the trip connect it drops the contactor out protecting the servers and other sensitive electronic devices from the voltage surge caused when the neutral is broken...the only problem is it keeps switching off the power every time the voltage drops below 180 volts or in the evening when it jumps to over 250 volts.
the supply authourity...indicate that the volotage problem is due to expansion in the area and the extremely old electrical infrastructure (still got old lead cables)...which they have no control over...mmmm...maybe they should upgrade the infrastructure?
so heres a tip for anyone wanting to move to your bussiness to a new location...
1st check that there is adiquate power ie...100...125...250 amps or whatever you require.
the voltage is stable
and the infrastucture can handle the exsisting load and future addtions.
you thought you just had to worry about the illegal cocs...dream on.