Safe Isolation the good and the BAD....

[@eddie_pegasus_electrical]

Great short and to the point video Mark 👊😎👍💙

[@dansparkyintraining]

👍👍👍

[@three-phase562]

Whilst I agree with the vast majority of what you said in the video, at 12:38 you made the comment that the isolator is off so you know there is no electrical energy coming down. To me this is wrong and I would challenge that comment. I appreciate that it is a new install that you have done and that can sway your perception, but isolators can still fail. The only time you can say that there is no electrical energy present is after the test for dead procedure has been completed, which in itself, is a live working procedure. That is why the isolation process of identifying, switching off and securing is best kept separate to the process of verifying the isolation, removing covers and testing for dead and ideally carried out by different people. Perhaps not a requirement in domestic so much, but more relevant in larger commercial and industrial installations. In larger installations incorrect identification of isolators is a big problem, condition of apparatus can also be an issue, you can even find isolators, or one pole of them bypassed for some reason. There is also the potential for back-feeds, stored energy and induced energy. I would also regard the splitting of a neutral as live working. If you have a diverted neutral fault, more likely in domestic, or an installation with a borrowed neutral, more likely in commercial and industrial, then the neutral will test as being dead initially. However when opened, you could find yourself with a live neutral bar or a live cable in your hand. You therefore then need to test for dead again once you have split the neutral. With a lot more solar being installed, now along with battery packs, there is a lot more potential for live working as those systems aren't always the easiest to isolate. Is not just about the terminals at the bottom of the isolator either, you will have a single insulated live cable running around the inside of the board. Not so bad if you are carrying out the required tests, but if you install a new breaker in a panel or exchange one, you are starting to manipulate wires, that may have damaged insulation and short to something or you may even accidentally pull the wire out of the terminal. Sorry if I come across as being harsh here, it is not my intention and I know it is difficult to make a video and include everything you want to in it.

[@electrician247]

Clearly stated several times the isolation procedure has been completed 👌. I am careful not to make my videos a how to thus its not shown. So no electrical energy is present. Entire purpose of the video in a nutshell. No solar is present on the install here but as always checking for live voltages as I discuss is vital. Your welcome to challenge 12.38 but in context of the entire video and what is discussed I've made the point checks have been made. Simply switching an isolator is not at all what is said or implied

[@MrImATarget]

What determines the size of main switch on a DB? i.e. 3 pole or 4 pole

[@electrician247]

Earthing arrangement normally dictates. Or of a UPS is in the system. TNCS can be 3 pole. TT needs 4 pole. UPS systems should also not open the neutral so 3 pole.

[@MrImATarget]

@@electrician247 thanks for the answer. Its just one of the things I have never really queried before. I just used to just take it as it came. So if I was given a 4 pole isolator that was what I would fit without even thinking about it.