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Guidance note 8 - Section 5 Protective equipotential bonding Im getting a bit lost here..... I have attached an image from the book, and my own version of the same image.... This section is about touch voltage and how that changes, if you add Protective equipotential bonding. The basic premise...

Just wondering how an insulation resistance tester actually works? I know how to carry out the test, but just wondering how does the meter calculates the values. Thanks

Large house. with 4 self contained flats. Improvement needs to be made to the shared MET. All flats on switched fuses, feeding CU's in the individual flats. Just wondering what others do when it come to switching off the supply to multiple flats. Obviously you inform them. Do you get them to...

Table 4D5 Is this just for Twin and Earth, or would it also include 3 core and earth? Or would you use table 4D2A for three core and earth (flat cable) Table 4A2 says 'flat twin and earth' for installation methods But Table 4D5 only says 'thermoplastic insulated and sheathed flat cable' so...

Would like a bit of guidance on protective bonding An installations gas service has main protective bonding connected to the MET (3 flats looped on one 10mm G/Y conductor) The water enters in plastic, in a communal hallway, it then runs in copper from the hallway into the flat. The water...

Received this email today... Dear Sir / Madam, I was wondering if you provide Electrical Installation Condition Reports (EICR)? If you do, I think I can help you by providing a subcontracting service for EICR. Often, we find that some electrical contractors simply don't have the manpower or...

If you have a TNCS supply coming into the property In the down stairs meter cupboard you have a switch fuse protecting a 16mm2 T&E cable feeding a CU in an flat in the building. I was just doing some Adiabatic sums on the 6mm2 CPC in the T&E ( Theoretical only, this is not a real example) to...

If I wanted to calculate the maximum length of a circuit, in relation to its Zs would the following transposition be correct.. So if it was a 2.5mm2 T&E cable on a 20 amp MCB. I would use 2.19Ω (BS7671) as my Max Zs, as this is at the maximum operating temperature. Not 1.75Ω as in the 80%...

I thought a fixed load was an immersion, and shower, a cooker. Any one appliance that has a maximum load. The cooker and the shower, have a load that can be altered. But are still classed as a fixed load as you can't go over its kW rating? Am I wrong? I ask in relation to the BS3036 fuse. I...

Just trying to understand the maths behind table 7.1 in the OSG ... Maximum length For a 20A RCBO (Type B) cable 2.5 - 1.5 (T&E) I'm presuming clipped direct as this will give you the longest run The Maximum Length is 42m. Now the volt drop calculation. Using Rated current of...

Apologies for the amount of questions. I would appreciate some thoughts on these please... Grouping factors for cable, and installation methods Grouping... AFAIK they are no they are no distances specified for when a rating factor has to be applied for grouping. So if say three circuits went...

Im off work so plenty of time to get myself tied up in knots over (Basic :() electrical theory, so.... I've been thinking about overload, in particular. 433.1.1 and appendix 4 My problem is where overload protection is not required. And the use of design current, instead of the rated...

This is related to domestic really So you have the supply into an isolator then on to two consumer units from the diagram.. Ze is at the origin ( Isolator) with the means of earthing disconnected. This supply Cable to the DB's what test on it would you perform on an EICR Now. on an EICR...

Just trying to calculate maximum lengths of cable for standard circuits (Just CPD) OSG tells us... A1 Ring - 100m2 A3 Radial 50m2 Now I don't find m2 a useful number, as it doesn't tell us the conductor length. Its not necessarily the run of the cable. So I thought I would use volt drop to...

When you measure Ze, I understand it has to be at the origin. In this drawing I have the incoming service , then onto an isolator, then the main Db and 2nd and 3 DBs Would you take the Ze from the Main DB or from the isolator? All the other measurements are Zdb and the CPC ? would remain in...

I have an issue with a pond pump UV light What would you expect the resistance between line and neutrals pins on a 24W four pin UV 2G11 lamp to be. Many thanks

I don't really understand touch voltage, I'm embarrassed to say... When I ask people they usually say , stop over thinking it , the RCD will take care of it.. Im not to keen on leaving everything to an RCD, Ive found a few that don't work as expected.. I know the principle. And exposed...

Could I just ask for some advice , as I am doubting myself..., or my test results Dual RCD board, in an unoccupied house, (between moves) Recent rewire, probably a year old - No installation certificates. Doing insulation resistance tests. Global test, gives poor readings, so I separate all...

A metal water pipe enters the building , Its a Extraneous Conductive part (ECP) so needs Main protective bonding to the MET. That same pipe, has a branch off it which then goes back under the floor (buried) and re appears in another room in the same house. (1) Does the second appearance of the...

Been left this to wire up by the plumber Im OK with wiring heating systems (Generally), but this has got me a bit confused Its a UFH manifold with a two port valve and pump, that need to be added to an s plan I have attached the wiring diagram Pg2 I presume that I take the grey and orange...