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electrical wiring

  1. J

    Time / current characteristic curves...

    Just trying to clear something up for myself, hoping someone can put it into layman terms for me. I'm looking at the time / characteristic curves in 7671. For example, 60890 Type B curve, p. 370. Taking the example of a 32a breaker, the line flattens off vertically at 160amps. All understood...
  2. F

    Adding extra sockets

    I'm not a qualified electrician, just diy. I need to add 4 double sockets above the workbench in my study. The total load isn't going to exceed 13amps. I considered just using a 5m 8 gang extension lead from the existing socket on the other side of the room and pinning the cable to the skirting...
  3. N

    Maximum ZS values GN3

    On page 142 of the latest Guidance Note 3 it list a 16 amp type B max ZS as 2.15, however i think 2.2 is the real value, it also states that at 16 amp type C is 1.1 ohms which is correct, but a type B should be double the value of a type C. anyone else have a view on this?
  4. J

    Calculating Fault Current...

    Hi all, quick question, hoping an easy one to answer. Just need to clarify this up in my own head. When calculating fault current from Zs, do I take Cmin into account? For example. Zs is 0.54 ohms So to find fault current I would calculate nominal voltage / Zs So 230 / 0.54 But, should I...
  5. Les Macaulay

    Inspection of wiring to new industrial dish washer

    Inspected a final circuit for a new dishwasher of the commercial type, rated at 4.3 kW, about 50M from the D/B. Final connection joint to the appliance flex comprises connector block in a dry wall box with lid lying on floor of commercial kitchen. C1, C2 or C3? Isolating switch on opposite...
  6. nicnic66

    Hot tub supply design?

    Is a hot tub classed as a 'water heater thermostatically controlled' according to table 3.2?
  7. Strima

    18th Edition Amendment 1 Corrigendum

    So they messed up the first amendment and have released another corrigendum: Link to original source: https://electrical.------.org/media/2420/bs-7671-2018_a1_2020-corrigendum-may-2020-read-only.pdf
  8. M

    What is maximum distance I can run 12 gauge wire to a shed?

    Hello, Need some advice. I have a 20amp breaker with 12g/2 underground feeder wire running to an outdoor GFIC outlet. 38 feet from breaker box to where it leaves the house and then 32 feet buried 24 inches deep (no conduit) to the 20A GFIC outlet. So from breaker box to outdoor outlet is a...
  9. J

    Overload, Overcorrect and ADS...

    Hi all, probably a couple of silly questions here, I know. I just need some clarification if possible. Firstly. Is there a difference between overload and overcurrent? I've always assumed they are the same thing but recently I have been considering this more and I'm reasoning that overload...
  10. N

    Question about electrical wiring in the ceiling

    Hello, I decided to tackle a leaky skylight replacement in my living room. It's an acrylic bubble 18" square and it was installed when the house was built in '86. To make thing more complicated for myself, I purchased skylights that are 45 3/4" by 22 1/2" (wife wanted larger skylights). I...
  11. L

    Submain/RCD Selection

    Hi there, I am new to this forum and I am finding the help very useful. Could someone please advice me on the following. So If I have a 60A Cutout fuse to the property how do you size the main switch, could a 100A be used. Also how would you size the RCD’s, why would one be 63A and another 80A...
  12. R

    Hi. I have an outside light which has a switch just inside the hallway. I am adding 2 more outside lights to be switched on using that same switch.

    Hi. I have an outside porch light which has a switch just inside the hallway. I am adding 2 more outside lights to be switched on using that same switch. I have ran 1mm cable from the switch line and neutral & earth to the new light and continued that to the 2nd new light. When I switch the...
  13. J

    Sub mains

    Hi all, I’m about to pull a sub main to supply an annex 16mm SWA, my question is how to do use the earth as a 63amp fused isolator switch only takes a Line and Neutral? or if anyone has any tips or know of a bit of kit that can help? Cheers
  14. A

    New Consumer Unit

    Hi. I'm new on here. I'm not an electrician. I'm just seeking some advice. I hope this is the correct section. My parents have just had a new consumer unit fitted. The electrician is NAPIT registered. He didn't leave an installation certificate. When I phoned him and asked about this he...
  15. W

    Kitchen rewire and isolator switch

    Hi guys. Electrician will soon rewire my kitchen and some questions arises about sockets and isolator switches. I think they look ugly and don't want them on sight. Is it possible to install only two isolator switches one for oven and hob, and the second for electric instantaneous water heater...
  16. M

    Conductors in parallel

    "433.4 Overload protection of conductors in parallel Where a single protective device protects two or more conductors in parallel there shall be no branch circuits or devices for isolation or switching in the parallel conductors " I am in debate with another spark. I have installed 2x2.5mm...
  17. W

    Burying Selv cable

    Hi, I hear the regs for burying cables don't apply to SELV cables anymore? Is that right? Are there any requirements for buried SELV cables now? Yellow tape, minimum depth, mechanical protection? I'm shielding at home for 12 weeks and don't have access to my regs book otherwise ild check...
  18. A

    Freeing up space in consumer unit

    Hi guys Hoping you guys could help. I have an 8 way RCBO board with all breakers used for dedicated circuits. Ideally I would like to run a dedicated circuit to a new combi boiler I've had fitted rather than it be plugged into the ring main to prevent nuisance trips etc however as mentioned...
  19. S

    Rewiring Bungalow and circuit design for Kitchen.

    Hello, I am getting a bit bogged down with detail as I always try my best to meet every best practice but I am very out of practice as I have been working outside the industry for 15yrs. All help appreciated. I am refurbishing my small 2 bed bungalow and have some questions for all the experts...
  20. D

    Lighting circuit

    Hi All, WIth new reg is it a true that the every lighting circuit have to be protected by rcd ?
  21. J

    Voltage Drop Design Current?

    When calculating voltage drop and using the formula mV/A/m x Design Current x length / 1000 = v Do I use the design current value after rating factors have been applied? Thanks again for any help.
  22. T

    Is an accessible switch not necessary?

    Recently the isolation switch of our shower broke, the electrician who came over to fix it have removed the switch completely and have directly connected the shower to the circuit breaker instead the box(red arrow). According to Installation and operating instructions by the manufacturer I have...
  23. B

    Why does the UK use rings for sockets?

    I take it you're allowed to use radials for sockets? So why does anyone bother with rings, seems like extra hassle to me.
  24. Nelder

    Non Domestic 20A Radial

    Hi, I'm curious to get peoples opinions on this non domestic situation please: A 20A SP&N radial Fed from a 20A MCB 70 degree singles, grouped in metal trunking fails with 2.5mm singles and even 4mm singles. I vaguely remember reading something that, if a cable is loaded to less than 30% its...
  25. Kingers

    16mm tails on 100A cut out

    Hello everyone, I have recently qualified, though yet to start practising, as an electrician. I have noticed, at my home, the tails from the (single phase) 100A mains cut out to the 100A rated meter, from the meter, to a 60A isolator and from the isolator to the antiquated fusebox are all...
  26. W

    Fire sealing an external hole?

    Hi, I'm drilling through the kitchen wall into the wooden leantoo. I'm using 20mm conduit through the hole, with a conduit box one side and a wiska box the other. Do I have to use any fire sealing? Whether inside the conduit or around it as it exits the brickwork? I found a link that said...
  27. telectrix


    I need to do the customer a report on this. done buy a supposed "electrician" via Bathroom installers. This SWA is for a 9.5kW shower. apart from the SWA armour not being earthed, the black core is used as cpc but no Gn/Y ID. joins in loftto T/E in a broken adaptable box with 30A 3 pole choc...
  28. S

    Using SY cable in a fixed installation

    Hi, got a job that’s coming up which involves putting electricity to a wagon that’s half way down a field from someone’s house. They want it so it’s like a caravan, so they can disconnect the power lead whenever they want and move the wagon around. There’s only 2 circuits in the wagon; 4 lights...
  29. M

    Dividing radial off FCU. Is it ok?

    I have a radial running from the CU to an FCU then to 2 outside sockets. Can I add another socket going from the 1st in another direction? I have included a diagram. thanks for the help people :)
  30. W

    Bonding Metal Railing

    Hi, I'm taking swa out of the shed and fitting it along a metal fence with metal fixing band. Swa goes into a wiska box then flex from the box to a light that's bolted to the metal fence. Circuit is protected by rcd. Does the fence need to be bonded at all? I'm guessing it's an extraneous...
  31. A

    What is this?

    Hi all, I was looking at a CU today and couldn’t help noticing it had two supply cables. Does anyone know if this is a DNO loop system from one property to the next (I know the photo isn’t the best). The board is located near the entrance to the property and it is a semi detached house.
  32. S

    Ryefield board

    Hoping to install (if things get back to normalish) a Ryefield board on a job soon. Haven’t installed one before, according to the drawing from UKPN, the meters will be after the ryefield board - will the suppliers do their own tails into the ryefield board or will I have to supply that? Seems a...
  33. N

    Should a shower isolator have a flickering dim light when off?

    Hi, I'm not an electrician, but wanted to ask for some professional opinions. My parent's shower isolator stopped working, so they enlisted the help of someone who they say is a 'qualified electrician'... Anyway, the neon is flickering when in the off position, and a brighter (non-flickering)...
  34. R

    2780kw ovens

    My cooker was wired to a 13a socket in the space behind the oven in a Persimmon new build, wooden construction. Some idiot cut the insulation back and reduced the strands in order to connect it, The fuse heated up. The 15 amp cable arced away but the fuse is still intact. Surely this is not to...
  35. Pretty Mouth

    Why are main protective bonding conductors sized as they are

    Hi all. Hope you are all well and virus-free. This question is not how to select main protective bonding conductor sizes according to the regulations. That I understand how to do. What I am asking is: Why do the regulations require such a large CSA for Main Protective Bonding conductors...
  36. A

    Minimum earth for tncs

    Hi all, need some help as I'm having a blank. Replacing a consumer unit on a tncs that currently has a run of 2.5 metre tails 16mm tails and 10mm earth. I don't want to waste money for no reason replacing them if not necessary, I know a lot of people would fit 25mm and 16mm earth but the supply...
  37. U

    Am I being scammed?

    Hey all! hope this is the right place for this type of questions! I have a new phev coming in a couple of weeks and as such I need to get a power outlet to plug in the charging cable. I live in an apartment building and have a private parking slot and a private storage room with its own...
  38. T

    Holes through joists

    Hi all Question regarding the amount of cables through holes in joists. Is there a set amount that you should stick to, or does it not matter how many cables are through a joist hole. As long as there is movement in the cables, finger gaps side of cables, reason i asked as seen about 8/9 cables...
  39. H

    Short circuit bypasses mcb and trips submain mcb

    Good evening A cable was loose in a ceiling void causing a short circuit this didn't trip the 10 amp 6ka type b mcb but tripped the 50 amp type b 6ka mcb that supplied that board back at the mains. I am wondering why this occurred other than me thinking the local protection isn't very...
  40. R

    Broken Immersion heater Element or electrical wiring problem?

    Hi there, DIY'er here I have an immersion heater that is not heating up water during the night on the cheap rate. The booster switch "top element" still works fine, but I can't work out if the bottom element is broken or there is something wrong with the supply of electricity to the element...
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