What is an electrician actually doing when testing a circuit? Whether it’s for for an electrical safety certificate or a new installation certificate🤔 Here is a short guide.
When a new circuit is installed, it must be tested before being put into service. This is professionally known, as the initial verification.
We are testing to ensure that the cable has not been damaged during the installation process. Also testing to ensure all the design calculations are correct.
A lot of maths is involved! Far more than you think👌⚡️
One of the tests is called an insulation test. This ensures that the plastic coating around the copper conductors is seperating the wires. If the wires touch you will get a ‘short circuit’.
The insulation test is basically a pressure test. 500 volts is sent into the circuit, to ensure that the plastic coating on the wires is working well. Making sure their will be no short circuits present, once properly energised.
The results also let us see if the circuit is close to failing.⚡️
Polarity testing, is carried out to ensure power is running in the right direction. Incorrect polarity is very dangerous. When a socket is switched off, it is to prevent electricity passing INTO an appliance.
With incorrect polarity, electricity passes into the appliance from the wrong end, the appliance will always be energised. When you switch that socket off your stopping electricity from getting OUT of the appliance, rather then entering. Most appliances will still work fine even if polarity is incorrect. It will still switch off. You wouldn’t be aware until👉⚡️⚡️⚡️
Continuity & resistance testing. Firstly we want to prove that circuits are continuous. Circuits that aren’t continuous, won’t necessarily not work. And it’s not just about the wires that are used under normal working conditions (the live and the neutral) the earth is the emergency escape path should something go wrong. Electricity is lazy, and want to find the easiest path back to earth. We want it to choose earth and we want to make sure the resistance is low enough to make that the easy option. If it isn’t continuous it isn’t going to escape as it should. It will take the 2 nd easiest path… You! 👉⚡️⚡️⚡️
Resistance testing, we ve all heard of electrical resistance. Thicker wire has a lower resistance, than thinner cable. Electricity can travel round thicker cable, faster, than thinner cable. Just like water can travel through a wide tube easier than a straw👌
Resistance has to be calculated and then tested, to prove that design calculation, with consideration for the total resistance, for the length of the total circuit.
Resistance needs to be low enough, to ensure that the trip switches cut out in the event of something going wrong. Electricity needs to surge quickly enough, to cause those trip switches to trip out within 0.4 of a second. To prevent the cable burning out & protect your life.
External fault loop impedance testing.
It’s not only important to resistance test on the circuits installed internally. We check If the resistance is too high within the supply, coming into your home. Electricity is not going to escape as quickly as it needs to, If the supply resistance is too high. This would be similar to having a blocked drain for your water.
Rcd s are like a super master trip switch. They trip when they detect the slightest problem. tests are carried out to make sure those trip switches not only trip out. But trip out within 40 milliseconds
Electrical circuits and systems should be periodically tested. This is known as an EICR report. Most people call them an electrical safety certificate.
Private homes should be tested every 10 years
Rental homes every 5 years, or with the change of every tennant.
From July 1st 2020 it is now law for private landlords to have an EICR report carried out when necessary.
Insurers may not cover you, if you have not maintained and safety checked any part of your home. Including the electrical system. Not to mention the fines in pace for not carrying this out.
Always use a registered electrician to carry out any electrical work. Registered electricians are assessed annually. To ensure competence, understanding, equipment calibration, insurances etc. But most importantly, registered electricians are up to date with their qualifications and changes to the ever changing electrical regulations.
Just because your electrical system works when you switch the kettle on, doesn’t mean it is going to work should something go wrong. And automatically switch off… in time!
A word of warning about periodic inspections. (EICR) You don’t have to be regulated, or qualified to test, to do these tests and reports.
Their is a difference between an electrician and a qualified inspector. Some regulated electricians don’t even have the testing and inspection qualifications and are not approved for this level of work!
Many contractors carry out these tests & reports from the comfort of their van. They are known within the trade as drive by tests.
Make sure your getting the right report. An electrical safety certificate is not a visual inspection.
Beware out there!
WE Specialise in : REWIRING THE NORTH WESTS HOMES. EICR reports (safety certificates). Fuse box replacements (consumer units).
You can get in touch anytime with any questions or some friendly advice 👍
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