Ze and PFC reading?

[sparky351355]

Type c mcbs reqd if pfc is so hi

 

[Des 56]

Type c mcbs reqd if pfc is so hi

Domestic max 100 A
Read GN3 page 54

 

[sparky351355]

Domestic max 100 A
Read GN3 page 54

Your point?

 

[sparky351355]

I've never come across such a hi pfc yet by the way ,get your meter checked out.

 

[HandySparks]

Type c mcbs reqd if pfc is so hi

Why?

As far as I know, the type doesn't bear any relationship to the fault current rating.

 

[Deleted member 72666]

Why?

As far as I know, the type doesn't bear any relationship to the fault current rating.

Type 'B's - 6kA (Icn)
Type'C & D's - 10kA (Icn)

 

[sparky351355]

Why?

As far as I know, the type doesn't bear any relationship to the fault current rating.

surely we are talking about the breaking capacities and not the fault current rating!!!!! with regard to the pfc?

 

[Noob2013]

Will try a different meter tonight and see if that's any better

 

[MDJ]

Hi all,


The Ze reading was 0.00 ohms .

No it wasn't, very very very unlikey unless your sat in a room with the main transformer, even then something would register.

 

[HandySparks]

Well, I was going to do a reply, but the forum won't do a 'Reply With Quote' on this thread for me, and keeps losing my text, so stuff it.

 

[amo]

has the meter you are using been calibrated recently? have you tried another meter?

 

[Dizzy_Maskell]

Not if the main fuse is a 1361 rated at 60 or 100a as the upstream breaking capacity of these is 33ka.

What is the regulation regarding this, I would think that if the Ka is higher than the protective device this is a defect.

I tested an install once that had old MCBs (needed changing anyway but that's another story)

The Ka on that board was >7 Ka I can't remember exact figure, the three phase 3871s where rated at a maximum of 3 Ka.

The overload for this distribution board was BS88 so obviously they would withstand the Ka.

My argument would be that the three phase MCB is not rated to that Ka and so may cause unknown issues under max fault conditions.

People's comments please and if I'm wrong on this (better safe than sorry) please be gentle

 

[sledgehammer]

I've seen and fitted mcb's type B that were 10KA rated. Hager, Eaton etc. RCBO's tend to be less I've noticed. I've also measured Ze as 0 when close to tranny but I've always known that below 0.2 standard meters aren't that accurate. An engineer once discussed pfc with me saying that sometimes you need to create some impedance on the incoming legs do this to drop it to a level the switch gear could handle.