Max Zs on TP boards

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oscar.maskell

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Hi asked yesterday but dynamite ding ruined the thread

Tested a three phase board at 2.4 Ka L-N (highest)

So for a three phase circuit this would be 4.8 double factor

The max Ka on the MCB are 4.5 so if there was a three phase circuit in there it would be incorrect

What code would people give this I was thinking an observation as there are lots of spare MCB in the board that could be used for three phase circuits

 
On the off chance you are not something to do with Norse mythology or Scandinavian folklore!

Are you meaning PFC/PSCC?

 
On the basis you recognise pfc etc it's obvious I was talking about this

So why not answer the question and help rather than try to belittle people I thoughts why the forum was there

No I am not supr spark I am asking a genuine question don't have time to waste

 
I thought yesterday that these 3 all seemed to be talking on the same threads at the same time trying to play each other off well afraid to say uve been rumbled

Well done clever clogs

 
In that case seen as you have asked so nicely

I wasnt trying to belittle you at all not my style Oh tetchy one. just wanted to know if you were asking the right question with the info you'd given. Give the wrong title get a wrong answer or no answer at all.

Tested a three phase board at 2.4 Ka L-N (highest)So for a three phase circuit this would be 4.8 double factor
Good so you do know what you are supposed to do, even if your terminology was wrong in the first instance for the posts topic title (which by the way would get you a X in an exam)

The max Ka on the MCB are 4.5
You are correct the mcb's in use are underrated for the max pfc..................... but what is the suppliers service fuse rated at?

Coding well thats up to you as the testing/inspecting electrician C3 or C2

 
I am not dynamite but tried to make a point yesterday by showing how this forum can be to harsh in genuine questions proved again today

A colleague asked a question that was really genuine and was shot down in flames for no reason and belittled why does this forum do that

It really is a great idea and could be a brilliant tool for all to use but it seems a minority use it as a platform to boost their own egos and prove how clever they are when I feel peoria know what peoria are asking but because the question is not asked as a 2391 exam question people find it acceptable to slam you

Sort this out guys I am sure genuine people are out there so lets not have the few rule the roost

Thanks m107 that's all I wanted to know don't need the lecture to though that's what I mean about the forum

 
I appologise if you feel I've lectured or belittled you.

I could have as happens on other forums sat here and ridiculed you for asking an incorrect question to the info you gave or I could have sat here and posted sod all, letting you dig a large hole before you got fed up & looked in the books for an answer to your question (has to be said you'll not find the answer under Max Zs though).

Now I dont claim to be an all knowing electrician who sits in an ivory tower self potificating about how great I am (I don't know of any here who do to be honest), but what I am is a run of the mill jobbing sparks who hopefully asks some relevant questions, shows some quality work in the photos posted & on the odd occation gives some helpful advice to those who genuinely do not know and ask a question......

So if part of that involves me asking who you are (remember all the trolling that went on yesterday) & "do you mean PFC/PSCC" so I can

  • determine if it's worth answering.
  • determine if it's a wind up.
  • determine what you are actualy asking.
  • determine if I do know the answer.
  • determine if you need a laymans answer or can take onboard trade speak.

then I'm sorry you'll have to live with it big boy.

End of.

 
Last edited by a moderator:
Not aimed at you directly but others have also been slated for simple mistakes yes u dean mean max Ka not Zs other things on the brain sorry but I do thank people who will answer helpfully so thank you

The yesterday's actions was just to prove a point and it did so end of that

 
Oscar, you have put max Zs in the thread title and then went on to talk about Ka (BTW, it should be kA, but we'll let that slip).

Does your meter not capable of measuring phase to phase PFC directly?

Just that the actual ratio is more like 1.8 times - so if you can measure ph to ph pfc direct you might find you've got no issue.

You have to forgive others for being unsure what you're asking about. Ask a quality question, get a quality answer. Or vice versa.

 
Thanks for that no my meter is only 230v so can't go phase to phase thanks for the 1.8 tip good to know :D

What I really need to know is

The max rating of the MCB is 4.5 and all the circuits are single phase

Does this matter that it's a 3 phase board and the Ka for 3 phase exceeds the max rating of single phase MCB

 
oscar,

As has already been suggested a quality question will get quality answers, normally.

Terminology, or the correct use of this is key to correct understanding.

It seems that you were descibing prospective fault current in thousands of Amps, the correct abbreviation for which is kA.

k being the SI descriptor for the ,000's multiplier i.e. x 103

A being the SI symbol for Amps named after Ampere, hence the capital letter as it is named after a person, as are Volts, V, ohms, ohms, Kelvin, K, Newtons, N, etc.

Also with the exception of kilo, or k, i.e. x103, all multiplier units in the SI system are capital letters, the reason for the lower case k, is, I suspect, but cannot confirm to eliminate confusion with the unit named after Lord kelvin.

Now the correct use of symbols in this communications medium can help in understanding, please remember all we have to answer your question is the information posted in front of us.

The written word in this form is easily misunderstood, or misconstrued. This is an unfortunate limitation. It is also why I "TRY" to be careful with my answers, and I am selective with said answers and responses as it is easy to misunderstand replies in this format.

If the information given is inaccurate, inadequate, false, or insufficient we cannot reliably answer the question.

I suspect that this could be the reason that you feel your post was not adequately answered, it may have been misunderstood.

Personally I ignored your thread, as I felt it was a badly formed question, which then turned into a slanging match / debate / call it what you will between two members whom I had no experience of. Thus I thought it better that I did not participate for fear of causing bad feeling between members, or members and the forum.

 
As M107 & others mentioned the suppliers fuses in the cutout will be BS88 OR 1361 and the rating of these will cover the high PFC . A fairly common problem in domestic single phase installations. I thought all breakers designed for a 3 phase board had to be a minimum of 10K

A house we are rewiring at the moment has its cutout about 8m away from the sub station. When we first started the job and i noticed the oudoor substation through the window, right next door i tested the PFC i got a silly silly high PFC reading ( cant remember it right now)

 

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