HIGH PEFC??
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Whats your earthing arrangements and Zs?
AndyGuinness
AndyGuinness
IIRC DNO only guarantee a PFC of <16kA on PME/TNCS
the cut-out fuse 'should' be rated to cope with this, ie, BS1361 or BS88 , rated at 16.5 & 88 kA respectively.
alternatively if you are still concerned use HRC OCPD in the CU
HTH
---------- Post Auto-Merged at 22:16 ---------- Previous post was made at 22:15 ----------
BTW,
nothing you can do will alter the PFC/PSCC/PEFC or whatever its called this week.
the cut-out fuse 'should' be rated to cope with this, ie, BS1361 or BS88 , rated at 16.5 & 88 kA respectively.
alternatively if you are still concerned use HRC OCPD in the CU
HTH
---------- Post Auto-Merged at 22:16 ---------- Previous post was made at 22:15 ----------
BTW,
nothing you can do will alter the PFC/PSCC/PEFC or whatever its called this week.
ANd your PFC is the highest of PSSC and PEFC,,,,
How's making it a TT going to help??.
How's making it a TT going to help??.
you will still have a high PSCC/PFC across Line and Neutral, and its the highest reading that is your fault current,
but by all means, if you wish to change to a TT system I would wholeheartedly recommend you do, providing you understand the implications of it,
I much prefer TT myself,
but the only way you will lower your PFC is to move further away from the substation/transformer.
why are you so concerned about your PFC reading?
but by all means, if you wish to change to a TT system I would wholeheartedly recommend you do, providing you understand the implications of it,
I much prefer TT myself,
but the only way you will lower your PFC is to move further away from the substation/transformer.
why are you so concerned about your PFC reading?
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Steps will love you now mate changing a tncs to tt lol
by how much?
they should be virtually identical on PME,
they should be virtually identical on PME,
its not my house, ive just done a periodic inspection and came across this. I was just concerned because ive never seen anything this high before? the transformer is right next to the house thow. My old boss just use to tell me that PEFC is the important one you should worry about, and i thought because this was high putting it on a TT would help in a way to bring the resistance up abit to bring the PEFC down. Like i said ive never come across it before and was just worried about KA rating of mcbs.
On all but TNCS, PSSC will be the highest of the two
And on TNCS PEFC and PSSC will be almost identical
And on TNCS PEFC and PSSC will be almost identical
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I think it's covered by the ka rating of the mainfuse as said above mate. There's a reg but I can't find it at the mo
what is your PSCC reading?
this would be helpful,
it would at least prove something,
bet your Ze is 0 ohms though
---------- Post Auto-Merged at 22:51 ---------- Previous post was made at 22:50 ----------
personally I dont like having a higher PFC than my OCPD can break,
but in this case, other than spend atrocious amounts of money on higher rated MCBs your only option is HRCs, if you really must.
this would be helpful,
it would at least prove something,
bet your Ze is 0 ohms though
---------- Post Auto-Merged at 22:51 ---------- Previous post was made at 22:50 ----------
personally I dont like having a higher PFC than my OCPD can break,
but in this case, other than spend atrocious amounts of money on higher rated MCBs your only option is HRCs, if you really must.
well,
usually I would say it will make it infinitely safer,
but, as the Tx is right beside you, chances of a dropped neutral would be virtually nil,
I would still TT it though, but not for the reasons you think.
in short, TTing an installation to bring down a PFC reading is NOT a solution, it simply will not work,
why are you so concerned about this Chicki.?
usually I would say it will make it infinitely safer,
but, as the Tx is right beside you, chances of a dropped neutral would be virtually nil,
I would still TT it though, but not for the reasons you think.
in short, TTing an installation to bring down a PFC reading is NOT a solution, it simply will not work,
why are you so concerned about this Chicki.?
you are not doing your job wrong, PFC is beyond your control,
if you really want peace of mind ring the DNO and have them confirm what BSxxxx and type of fuse is fitted in the HED,
as I said, both BS1361 and BS88 will be fine as PME kA will <16kA
if you really want peace of mind ring the DNO and have them confirm what BSxxxx and type of fuse is fitted in the HED,
as I said, both BS1361 and BS88 will be fine as PME kA will <16kA
Chicki,
You need first to understand the ramifications of your findings.
Then look at 7671, then the other relevant standards, 60947 I think from memory, Annexe 4?
It may be ZA I can't remember now.
If you are doing PIR's you really should have a grasp of this.
Get to the bottom in your own head of what is concerning you and spell it out to us then we can alleviate or explain each concern, thus either dispelling them or explaining the results/solutions.
You need first to understand the ramifications of your findings.
Then look at 7671, then the other relevant standards, 60947 I think from memory, Annexe 4?
It may be ZA I can't remember now.
If you are doing PIR's you really should have a grasp of this.
Get to the bottom in your own head of what is concerning you and spell it out to us then we can alleviate or explain each concern, thus either dispelling them or explaining the results/solutions.
alternatively, if you really wanted to be in control of the situation, fit yourself a 63A(or 80 if appropriate) switch fuse as main isloator,
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