WebJun 8, 2008 · Zs reading above 100% of max Zs so too high for disconection in the req time - this reading is for one of manyand is for some shop lights which is a 10amp mcb and is 2.5mm with cpc 1.5mm and 60898 mcb type c 3 phase 400volt thanks if you need any more info i have the full report thanks again danny001 Rank: Tradesman Progress to next rank: … WebFeb 24, 2024 · #1 Hi all Is there different amounts and table for a Tns system to a tncs reguarding the mcbs maximum Zs. I have a Ze reading of 0.40 which is fine but all my circuits have a high Zs reading. Eg. Two cooker circuits both 40A type B mcbs are getting a reading of 1.22 ProDave Twatt ™ Supporting Member Joined Nov 28, 2009 Messages …
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WebDec 7, 2024 · Confirming that Zs does not exceed the acceptable and permitted maximum value according to the Wiring Regulations is an important test that should always be carried out after any electrical … WebAug 3, 2009 · Your Zs reading will be higher at the furthest point on the circuit. Before testing, the main equipotential bonding conductors are disconnected but not the connection with earth, this is done to prevent parallel earth return paths and to ensure that there is no reliance on the service pipes for gas and water for effective earthing. flower mound high school rosettes
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WebFeb 3, 2024 · Zs = Ze + (R1 + R2) – Zs is the earth fault loop impedance (Ω) – Ze is the measured value of external impedance (Ω), and – (R1 + R2) is the measured value of resistance (Ω) for the line conductor and protective conductor, at the most distant point or accessory from the distribution board or consumer unit. WebMar 24, 2024 · For overcurrent devices not covered by those tables, another reliable source of information on the limiting values of Zs must be consulted, such as the manufacturer’s data. Where the protective device … WebJun 29, 2010 · Thats GOOD for a TT TT means you are using a Rod into the ground for your earth, Zs CAN be as much as 1666.66 ohms and still be ok for 30 m A RCD protected circuits, although a Max 200 ohms is recommended. TNS supply Maximum Zs values do NOT APPLY TO TT installations See BRB (BS7671) Pg 50 Reg 411.5 TT Systems and … flower mound high school prom 2023