type C rcbo's

[steptoe]

Ok, but it still discriminates N-E fault, which is the point of the RCBO, no need for double pole, you don't get that with standard single pole mcb so why would this make a difference.

but you still have the neutral-earth fault present which can then daisy chain.

and with a SP MCB you will more then likely have a DP RCD to disconnect the N under N-E fault conditions

 

[Steve3948]

but you still have the neutral-earth fault present which can then daisy chain.and with a SP MCB you will more then likely have a DP RCD to disconnect the N under N-E fault conditions

Based on that theory would it not be a case then that under a N-E fault condition all RCBO's would trip, which I have never witnessed.

The Hager schematic diagram shows the mechanism breaks L&N under fault condition, but I see your point and will look into this further, because I must admit I thought all RCBO's disconnected the neutral under fault conditions.

---------- Post Auto-Merged at 22:52 ---------- Previous post was made at 22:25 ----------

but you still have the neutral-earth fault present which can then daisy chain.and with a SP MCB you will more then likely have a DP RCD to disconnect the N under N-E fault conditions

Steps, you are correct a lot are indeed single pole switched, good job I'm not a lover of them, makes cabling inside board a right mess.

 

[steptoe]

horses for courses Steve

they have their uses in the right circumstances.

 

[park1]

well Im thinking these are SP RCBOs, so whoever uses them on a TT needs shot!SP disconnection is NOT adequate for TT. IMHO

they are probably type C cos that was what the wholesaler had in stock, and thats the only reason,

and the installer was a muppet and didnt know any difference,

bit like folks saying if you have 30mA protection you can have 1666 ohms Zs ! utter nonsense, you could probably get that through the fabric of the building without any cpc's

That would depend upon the Design

---------- Post Auto-Merged at 23:15 ---------- Previous post was made at 23:13 ----------

Your not going mad Steve, many are now single pole , switched neutral

 

[steptoe]

That would depend upon the Design---------- Post Auto-Merged at 23:15 ---------- Previous post was made at 23:13 ----------

Your not going mad Steve, many are now single pole , switched neutral

or how you interpet the regs,

and there are differing opinions among quite a few members here as to what is or isnt required,

and yes, you can design whichever way you see fit, as long as you know it complies, or the deviations box is filled in.

 

[speedster]

Hi Nicky. Sorry for the delay in replying.

What the guy at NAPIT was saying, was, although the rcd element of the rcbo should take care of any earth fault,(assuming the Zs figure is not too high) overcurrent protection still needs to be considered. Hence the Line / Neutral loop measurement. If this value was higher than the corrected maximum Zs value for this breaker (c type rcbo). The circuit may not comply !

Hope this makes things a bit clearer.

Speedster.

 

[park1]

AND the neutral earth loop Why?Line Neutral loop Still Why?

How do you intend on complying with chapter 43? live conductors need protecting too

 

[Nicky Tesla]

Hence the Line / Neutral loop measurement. If this value was higher than the corrected maximum Zs value for this breaker (c type rcbo). The circuit may not comply !

No Sorry you've lost me!............Line / Neutral loop ? Nothing to do with ZS, touch voltages, electric shock times, adiabatic equations, nothing nada!.......who on earth (if you pardon the pun ) does that?

 

[park1]

Hence the Line / Neutral loop measurement. If this value was higher than the corrected maximum Zs value for this breaker (c type rcbo). The circuit may not comply !
No Sorry you've lost me!............Line / Neutral loop ? Nothing to do with ZS, touch voltages, electric shock times, adiabatic equations, nothing nada!.......who on earth (if you pardon the pun ) does that?

Me, and so should you

 

[professional]

On a TN system, RCD`s are only used for ADDITIONAL protection ....

 

[Nicky Tesla]

Me, and so should you

Why?

 

[park1]

Because you need to protect the cables against fault current

 

[Steve3948]

Because you need to protect the cables against fault current

$park look at my attachment in post #6

What do you think.

---------- Post Auto-Merged at 00:07 ---------- Previous post was made at 00:02 ----------

C Type 32A RCBO is 5333X more sensitive than 32A B Type alone.

 

[park1]

Had a look Steve, speedster and myself are referring to L - N fault current.

---------- Post Auto-Merged at 00:13 ---------- Previous post was made at 00:10 ----------

I'm referring to post 28 Steve.

---------- Post Auto-Merged at 00:18 ---------- Previous post was made at 00:13 ----------

The problem with MCBs is they are all or nothing .

 

[steptoe]

I still think a good old 1361 is better anyway, but what do I know, they can only handle 16.5kA

:|

 

[professional]

The main problem with BS1361 fuses is that they do not generate enough revenue for the mcb importers/labellers masquerading as manufacturers.

As for rcd`s/rcbo`s - they are VERY profitable for the "brands" - a typical rcbo costs them no more than

 

[park1]

$park look at my attachment in post #6What do you think.

---------- Post Auto-Merged at 00:07 ---------- Previous post was made at 00:02 ----------

C Type 32A RCBO is 5333X more sensitive than 32A B Type alone.

Steve, the link refer's to L-E fault

 

[Nicky Tesla]

In most cases it would meet the requirements.View attachment 3764

......Just Sayin.........

Ye This is post No.6 which obviously talks about Zs being L/E Loop........So where on earth does L/N loop get involved?

you have lost me mate:C

 

[sparkytim]

The "O" part of a RCBO is for OVERCURRENT or in simple terms equal to an MCB, so protecting against OVERLOAD and SHORT CIRCUIT faults, hence L-N Loop values are relevent.

The RCB part takes care of EARTH FAULTS, and relate to the Zs value.

 

[Nicky Tesla]

yes i know what the "O" stands for, but L/N Loop eh!

Earth faults need a very low ohm range to make sure you get high enough currents to trigger off the MCB before 0.4 seconds. ie before someone dies (in theory)

Overcurrent is different. A flow of 30A may flow through a 10A MCB but will not trigger off the MCB before 0.4 seconds cos the fault is not seen as passing through a person for eg.

What i think you are getting at is short circuit protection ie a direct short from live to neutral and not to earth.

Well no.....All the Zs figures are to do with the 0.4 second Diss time for earth faults and have nothing to do with short circuit faults. But if you can prove they do, then do it.