I have recently signed up for your 17th Edition course and just completed a first fairly quick run through the book with your slides. Will now start again being more thorough and start going through the workbooks. As I have gone through the regs I have “tested” my current home wiring set up (I recently bought the house and it was rewired about 2 years ago) to see how well it complies. This has been a useful aid to my understanding but has raised a few queries in my mind. Specifically:
1. 526.3 is clear about all connections being accessible for inspection. So would a junction box with screw terminals under floorboards used to connect a spur into a ring power circuit be against the regs? If the junction was an enclosure with say Wago mechanical locking terminals would that then make it more acceptable?
2. I have a ceiling constructed of plasterboard on a galvanised steel U channel structure. Cables simply run over this. The U channel is about 30mm deep and the plasterboard and skim say 15mm so cables don’t meet a requirement of being 50mm above the ceiling 522.6.201. However, pragmatically the screws holding the plasterboard to the framework only penetrate it by about 5mm so no real risk of hitting cable. What would you say is the correct way to run such cabling! How acceptable is pragmatism?
3. 559.5.3.1 through wiring. If a standard ceiling rose with L, N & E in and out and switched line is replaced by say a recessed down lighter which would not typically have all the necessary terminations is it acceptable to make additional connections needed in a suitable enclosure?
Enjoying course,
Thanks
Rob
Hi Rob,
1. It all depends on whether a junction box with screw connections is accessible for inspection and testing or maintenance. If it was just a matter of moving the carpet to one side and popping a floor board up then it could be argued that this is accessible. Adding it’s position to any drawings or on any certification and writing on the floorboard ‘electrical connections below’ could also assist in it being accessible. Or you could as you say use a maintenance free junction box complying with BS 5733 (526.3 vi). Personally, I don’t have a lot of confidence in these things and I would sleep better with a screw terminal junction box under the floor than a MF junction box.
2. This is a common issue where steel frame supports the ceiling. 552.6.201 states that cables should be in a position where they are not damaged by the fixings used to support the ceiling. ie 50mm clearance or one of the methods from 522.6.204 should be used (steel conduit, swa, SELV etc). What we used to do on-site was to run all of the cables through loops made from cable ties attached above the ceiling (quick and cheap) or run cable tray above to maintain a 50 mm clearance.
3. 559.5.3.1 through wiring relates to the practice of wiring a chain of lights through each other. A practice we used to use shop-fitting decades ago where fluorescent lights are mounted in rows butt up to each other with all of the wiring running through the fittings. What you are referring to is the loop in method of wiring a lighting circuit. If you are changing a ceiling rose for a recessed down lighter then you’ll need 559.5.1 (i) to (x) which list all of the recognised methods for connecting lights to the wiring. Have a look at (viii) appropriate terminals enclosed in a box complying with etc…
Hope this helps and I’m glad you’re enjoying the course.