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I agree but in my post above I imagined L>E @ 20mA and N>E @ 20mA so the toroid is balanced with no net flux differential. I can't get my head around this. If what I say is true (I'm sure I am wrong) then an RCD handling two phase (two lives) accommodate any amount of leakage to earth...

I am struggling with it. I think I need to draw it out but just a thought experiment for a moment. Imagine a simple toroid with N current wrapped around one side and L current wrapped around the other. Now imagine the output of N is connected to E with a current of 20mA. Now imagine...

That is a really interesting thought. For my own understanding if there is a "background" N-E leakage of say 20mA the RCD should sit there and not trip. If a L-E leakage develops, say a 20mA then the differential is zero. So the N-E leakage has essentially raised the RCD trip threshold...

I don't know the system that you refer to but if this is to reduce any AC component or transient noise component from "getting to" the alarm electronics then put it as close to the input to the alarm as you can on the 12 Volt DC input to the alarm PC board. The 17 volts sound like it might be...

You will need test equipment. Either a multifunctional or individual insulation tester, EFLI tester, RCD tester, voltmeter and low ohms resistance meter. A current clamp and multimeter are also indispensable. When you say you are going to set yourself up as a domestic installer are...

Sparkticus PL/PI claims 19 years = 0 8)

If you are going to run a business then you need to do it right, not cheap and I am not being rude. If you want electrical business then you need to join a "well known" scheme. Technically any scheme will do but you won't get much electrical business under a Corgi heading. Most estate agents...

That is a surprise to me too. There is enough confusion about the self certification scheme without that and as you say what happens if you sign off several jobs then fail the assessment? No wonder there is so much confusion and condemnation of the entire self certifications system!!

I can't add much to what has been written. Have never made a claim so I don't know if it is really worth the money as such. It's mandatory if you run your own company/sole trader/self employed etc so from that point of view I see it as another business expense and offset it against tax. The...

Is it safe to come back in now? :?: Brilliant!! your lights are on (small pun intended) :lol: Don't know what happened to the site last night, could not log on all evening and I see BASs desk was hit by a twister scattering his carbon copies everywhere :mrgreen:

I'm rubbish at both, my wife does any wallpapering :) Try this, when you look at it this way there are only THREE groups of connections: All these REDs connected together. Not all required in the same hole but must be connected via the brass connector block. 1)-RED Live loop in...

Please wait for a more expert (DNO) opinion but that looks like TN-S to me.

Try this more details 1)-RED Live loop in (this red will be in the same cable as the black in 5 and should be connected to reds 2 and 3) 2)-RED Live Loop out (this cable will be in the same cable as the black in 6 and should be connected to reds 1and 3) 3)-RED Live to switch...

With TN-S you may see a direct main earth connection to the outer sheath otherwise unless the TNC-S is labeled then no real visual way to identify. There really is no best system. With TNC-S the earth and neutral are one in the same which is fine unless: 1) The neutral is broken...

I am assuming you are competent with electrics and with electrical safety. Look at the service head and identify the main earth connection and the main neutral connection. With everything off at the CU (and the main earth disconnected to the CU) do the following: Measure across the MET...

If that is definitely the case then you could export the TNC-S earth assuming you do actually have TNC-S. Remember that even when you use an internal earth conductor you must still ensure that the outer armour is earthed via proper terminations (piranha nuts are in my opinion best)...

Possibly like this -RED Live loop in -RED Live Loop out (to next ceiling rose) -RED Live to switch (t&e with two reds) -RED Switched live from switch (t&e with two reds) -Black Neutral loop in -Black Neutral loop out (to next ceiling rose)...

That's a good point, the main issue does need urgent attention. This reminds me of the (I have forgotten the actual flight details now) pilot who allowed his aircraft to lose altitude and crash into the ground while he and the co-pilot were fixated on finding out why an instrument light was not...

I think because of this "Wiki's emphasis is on content, not presentation" Though being naturally skeptical, I am skeptical :|

It may look like the earth return path but is it simply using the boiler chassis as a ground? If so then the small (very small) current loop will be within the boiler circuit and not reliant upon an actual connection to earth. Though a floating earth may have an effect on the circuit. Having...