Welcome to our Electrical Forum - We started out providing electrical advice just
for the UK - But now we have specific advice for the USA too! - Register for free and
share American Electrical Advice.
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
right I get a bit confused with working out the Tabulated values (I am training and have exams tomorrow for Initial verification) on the Ze and Zs anyone on here what to explain how this works on the earth loop impedance, please can someone explain what I am overlooking ?thanks, Jules I...
I'm in the final stages of completing my electrician course, and I find myself confused (again) by EFLI.
In the textbook provided is this:
see below for each circuit.
Calculate the maximum Zs for each circuit:
Complete the table.
The answers given in the textbook are said to...
So I've been told by the NICEIC not to use the 80% rule for max Zs (even though that's the table provided on the inside of the cert books). They want me to use the 100% values from table 41.3 in the BYB. Not a problem.
However I can't seem to find a table for the BS EN 3871 MCB's in there...
Repairing a 2kw convection heater in our workshop office and I'm getting zero resitance on the min/max dial at any setting. What is the value for min and max as need to lever the spacing to get a resistance but don't know if it's too much or too little
I was doing my r1+r2 tests on a lighting circuit yesterday in a 6 bed house over 3 floors. Approximately 20 points not including switches. Mainly pendants but some light bars etc and almost all LED or low energy halogen type bulbs. Closed circuit r1+r2 values range from 0.88 on ground...
I know that the 80% values are applied in regards to operating temperature etc but NIC paperwork asks for the max permissible values of bs7671.
So when do you guys apply the tabulated values?
I've done commercial condition reporting in the past with a company that used their own test sheets...
Hi for a ring circuit, is there any need to measure and enter R1 + R2 values on a schedule of results ? Because an r2 value is already measured (together with r1 and rn). If I needed a ring R1 + R2 value to calculate ZS (although i would find ZS with a socket tester so really no need; but if I...
I have a ring circuit where the Zs reading taken is higher than maximum allowed values.
the circuit is protected by a 32a RCBO type C device, Zs = 1.43.
I have currently have tightened terminations which has brought it to its current value.
as i have been out of the game for a while...
Iv been given the scenario:
6 circuit earth fault loop impedance values were recorded. Each circuit has type B cb.
referring to the maximum values, show by calculation if these values are acceptable.
so I can't do zs =ze+R1/R2 because they've not provided me with ze.
doing some research it...
So, when I did my 2391 I&t course I was told to use to values in table 41.3 of the regs for max ZS value for rcbo which provide earth fault, and over load protection. Recently a colleague of mine said you should use the value in table 41.5 which states a max permissible ZS of 1667 ohms. I don't...
Struggling on this one.
Anyone know where I can find the Min PSCS Values of Type gG fuse,10A 500V (10 x 38mm)? IEC 269-2
I've got a load of 230v lighting circuits protected by them but google is not my friend today......
So disconnection time of 0.4 seconds?
Hi I have a Fluke 1653b and it claims to have Pass/Fail indication on RCD's ?? Where? Is this on the auto mode?
I can only get it to auto test then I have to scroll through all the measurements. There is no mention of this feature in any of the manuals?? Help!!!
I have continuity measurements on a ring final circuit of: L/L 1.4, N/N 0.78, E/E 1.7
Loose connections somewhere?
There is a new CU with RCD.
Insulation resistance measurements are good.
There is a boiler added into the circuit as a spur.
Any suggestions or comments?
:) :) :)
Much though I don't like it, once in a while I use a second hand MCB - for one that has long since gone obsolete and new ones are unavailable. What about testing used MCBs before reusing them, does anyone actually do this?
I just tested a 5A MCB at a couple of values of loading, it seemed to...
Hi can somebody shed some light upon correction factors for earth fault loop impedance. I know that the vales of zs in bs 7671 are if the conductors are running at max temp ie worst case scenario , am I right in believing that if you get a measured result you apply 0.8 to it?
I might be COMPLETELY wrong.... but I have recently finished my level 3 in college and I'm sure I was told that if a Zs value is higher than the max reading in BS7671 it's okay if it's protected by a 30mA RCD, so it passes. I sort of remember writing 'satisfactory' on the test form next to Zs...
BS7671 tables only go to certain size fuses eg how can I find max ZS of 400 amp BS88 - 2 on niceic test sheets they ask for a max value out of regs table I have only managed to find a busman fuse chart which differs been told by employer to use these values on sheets any input would help thanks
Hi guys had a conversation with the boss in the office after work today about a zs I got on a 32A c type rcbo bs 61009, the earthing system is TN-C-S, he said he wasn't worried I got a zs reading of 0.90 even though a type c 32A rcbo has a max zs of 0.72 his words were "it's just like a TT...
ElectriciansForums.net (formerly known as ElectriciansForums.co.uk) was setup in April 2006 to provide free electrical advice to both professional and DIY electricians. Whether seeking advice for auto electrics, trying to find electrical installation condition reports (EICR) form downloads, or whether you're here just to talk to other electricians; we've been a first-choice website for tens of thousands of sparkies for well over a decade.