questions asked about electrical installations and problems

[murdock]

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?

[Martinco]

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.

Well.........It is quite apparent that I am the culprit and it seems you want to visit the site to inspect the cap and the motor.
Just one question............should my wife be in the bath at this time for a real live on the spot inspection ?
Or will a "dry" inspection with no ancillaries or distractions be ok ?

[mikilianis]

I am listening to what you are saying perhaps you could share your knowledge about the correct selection of circuit breakers

[Sparks]

Almost impossible to guess correct answer without all the details. Some browsing on YouTube & the likes will deliver a clip of a guy standing in front of a DB which had under-rated breakers in. The powers that should be ought to make viewing of footage like that compulsory for appies. They will never again replace a breaker without checking the kVA rating.

[Gei]

The powers that should be ought to make viewing of footage like that compulsory for appies. They will never again replace a breaker without checking the kVA rating.

I agree seeing as i was an appie up until the other day. And an appie cant always choose his tradesman, and one can only learn so much in 2years. So where do we get the information we need so not to kill people! Is there not an electricians handbook out there that i can flip to when in doubt? Internet is ok but books are better. Where do you guys go for info? Thanks allot

[Sparks]

You have already made a good start by registering here. There are guys here with plenty of experience and knowledge. Read through some of the older posts when you have free time and don't hesitate to ask rather than take a chance. It could be your last.

[NTS2011]

Hi Gei,CBI (Circuit Breaker Industries) have a program called CBI V3.1.With this program you just fill in the information and the wizard will do all calculations for you (Cable size,Breaker rating,Transformer).In fact it works out your full Bill of material required.I have a copy,but it is too big to upload.Their is also other programs like My Ecodial from Schneider Electric.

[Piyush]

Hi... can you guys please assist as i installed a SUB DB in the garage, there was an existing power cable to the garage a 6mm flat twin & earth, i've extended that cable to my SUB DB, the reading i get is 267V why is that?

[Dave A]

What is your voltage at the point of supply for the installation (main switch)?
Have you identified where this cable is supplied from?

[AndyD]

Same questions as Dave, also what instrument were you using to measure the voltage and is it L-N or L-E? Are you a professional sparky?

[Piyush]

Hi Guys... i've ran a new cable from main DB to Sub DB.... Voltage 232V perfect... use a majortech multimeter. i am registered electrician lacking experience, i really appreciate the advice...