Where do people record the Ze & PFC of a 3 phase installation, if there is say 10m of 25mm tails between the 4 pole isolator (next to the meter) and the 3 phase distribution board, therefore some (though negligible) resistance?
Do you tend to test at the origin, and record that result, or do...
If the max Ze for Tncs is 0.35 but you had a 1361 60amp fused isolator before the c.u with the 1361 having a max Zs of 0.56 (from the 80% chart) if the recorded reading at the c.u was let’s say 0.47 ohms would that now be considered to comply? i can’t see why it wouldn’t.
Afternoon Ladies & Gents,
I'm a new member to the forum so thought I'd introduce myself.
Been qualified for around 10 years and have finally set up on my own. I am new to the test and inspection side of things so I am seeking advise on the following question. Any help would be greatly...
This may sound like a daft question but in bs 7671 does it state anywhere in it about max ze values
ie
tncs--0.35
tns--0.80
tt--21
I was jut wondering,I can find max zs but not ze ?????
Hi Gents and ladies,
I have been asked to quote on installing a couple of extra socket on a TT system.
When checking the existing installation my Zs readings on the ring are coming out at 39.8 Ohms (most remote). This is unacceptable (table 2d OSG). I then checked Ze readings which are...
Hi,
I'm in my second year at college, but I'm a bit unclear on what the max Ze should be for a TT system. I know that the regs say 200ohms, and my tutor said that it would be acceptable if you found an earth rod which gave a reading of 200ohms. However several of my mates who have been qualified...
Have a job where Ze is 0.36 ohms on a TNC-S with 80A BS1361 suppliers fuse. The general rule, as per OSG (page 11), is if Ze is below 0.35 ohms then this is acceptable, but that relates to a 100A fuse (OSG fig 2.1 on page 15 refers). Now I believe that this installation should comply, so have...
Hi folks.
Can someone clear this one up please.
Exisitng TNS system to a domestic, max permissable Ze is 0.8 ohms.
So if there was a fault immediately after the cutout head 230v/0.8 ohm a fault current of 287 amps would flow, if the PD was 100 amp BS88-2 it would take 100 seconds to operate...
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