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  1. Michael J

    The maximum value for Zs on a TT system is 50/I delta. So for a 30mA RCd is 1667 ohms

    why is this not the case if the final circuits on a TN-S or TN-C-S system are protected by a RCD? Funny what you think of when you can’t sleep
  2. dc-electrix

    Maximum demand and diversity electric flat

    Hi All, Making some alterations in an existing flat and scratching my head about required supply to flat. It is all electric, 1 bed, 1 bathroom. Electric shower 9.5kw Instantaneous Water Heater 9.5Kw Cooker Oven & Hob 6Kw 1 Ring main 3 Electric Heaters...
  3. D

    Maximum Luminaire Weight Supported by Plasterboard Ceiling

    Are there are any regulations/guidance on the maximum weight that a luminaire can be if it is only supported by the plasterboard ceiling and not fixed to any joists or noggins? I have a customer who would like a (heavy, but currently unweighed) light fitting from their old house fitted in the...
  4. gazdkw82

    Maximum Zs values for BS3871

    Where can I find the max Z's value for a BS3871, type 3, 32A MCB? Iv had a look through BS7671 and done some searching online but I cannot find it. IV found some tables with listed Zs values for a 3871 but I have no idea where they originate from or how old
  5. F

    Maximum number of lighting points

    Hello, Could any Irish members on here either tell me the maximum number of lighting points permissable on a circuit? I seem to remember a Fàs teacher mine saying that it was 10. The reason being that it's to do with a property being put into darkness in the event of a fault. I also think that...
  6. M

    60947-2 mccb maximum zs

    Can't find any data on these mccb if anyone has the ia for 60a,62a,80a,125a or 250a please post . Pete 999 am looking at you
  7. littlespark

    Maximum load across both sockets of a double socket

    We've had this discussion before, but does anyone have any idea what load can be put through a double socket? The socket in question is an MK logicplus, installed in a commercial kitchen. The supply cable is 6mm, converted from a previous cooker circuit to a double socket. (information gathered...
  8. S

    Maximum Zs on Circuit details schedule

    hi guys, Seen on the circuit details schedule in a DB on our site, someone had inserted Zs values for the circuits as follows. 16a C type breaker as 1.44 ohms 10a C type breaker as 2.30 ohms 80a C type breaker as 0.28 ohms I believe he’s calculated Zs by doing (in the case of 16amp c...
  9. T

    Ze at its Maximum Measurement

    If the Ze on a TNS supply is measured at 0.8ohms, is this still acceptable? Technically it is bang on the maximum. DB is 100A Main Switch with 30mA RCBO's on all circuits.
  10. G

    maximum residual current RCD

    Hi Everyone, I would like to confirm a question I saw the other day regarding working out the residual current on an RCD The question was similar to the following An earth electrode has been measured and the following readings were taken 1) 21 Ohms 2) 21.02 Ohms 3) 20.8 Ohms What is the...
  11. Y

    Maximum Current Capacity

    How much current capacity can handle in a 16 sq. Mm. Wire size in ac 415 volt supply? Because i have 2 pump motors that will connect to a power source of 415 volts ac 3 phase; 1 motor is 5.5kilowatts and another one is 7.5kilowatts. Both motors will run intermittently and supplying different...
  12. Vortigern

    DCP 161 implementation April 1st and calculating KVA, maximum demand

    I have alluded to this in previous threads. The commercial site I work on has asked me what I think the total KVA for the site is. Having looked at various ways of viewing this I am getting lost with it. So if I just say kVA = ( V*A*1.73)/1000 and assume supply is 400V and take the main incomer...
  13. B

    Maximum age of wiring

    Hello, I live in a house where part of the wiring dates to 1960 (exact). Now I know after ~30 years old, a rewire is advised. And at 58 years it should definitely be rewired, but it's going to be difficult to convince my parents to have the house rewired soon - as we have 5 people living here...
  14. E

    maximum allowable height for scaffold tower?

    really trying to get the customer to see sense, they have supplied scaffold tower for lighting replacement about 5metres off the ground, which i have been pottering away at with this shitty scaffold tower getting stuck in the sand below and hitting against the beams of the shed itself almost...
  15. G

    Help with Maximum Demand needed

    Hi, I am studying to become an electrician. I got a question wrong on a practice test. Can anyone help me understand maximum demand. this is the question I got wrong..... Question 27: With reference to the nature of the supply, which one of the following can be determined by calculation...
  16. A

    Maximum distance between collectors and tank?

    Hi, I'm looking at installing a solar water system for a friend. He runs a B&B so has much higher hot water needs during the summer, and also a very high annual bill for heating and water. So it seems like he's ideally suited for a solar thermal system to at least reduce the costs. We live in...
  17. W

    Zs ohms with maximum rcd ohms

    If the maximum zs is okay up until 1667 ohms protected by a rcd why do we care about maximum disconnection times for the mcbs e.g why do we test and it's important to meet 1.37 or 1.1 zs on a 32 amp circuit
  18. J

    28A in 4mm cable 6.5kw hob

    i need to wire in an induction hob which is 6.5kw and the cable already chased in is 4mm and would be a real pain to replace for a bigger. I just wanted to know if it would be alright or play it safe with a 6mm?
  19. S

    Maximum breaker size for DB (solar PV)

    Hi, Can anyone point me in the direction of the regulation / code for the max solar MCB size when connecting into a spare way of a local distribution board ? Eg. Is it possible to connect a 100A breaker into a 100A board ?
  20. Cadgey123

    DNO maximum demand message.

    Just started doing my first block of flats as a Qualified supervisor. I have 5 flats and a landlords supply to wire up. Done my calculations a while back and told the DNO I would need require ADMD of 12.5 kva for each flat which I thought was reasonable, Considering I have 3 rings, 2...
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