BS60947-2 MCCB

[mark64]

Can anyone please help!!!!!

What is the maximum Zs permitted by BS7671 for a BS60947-2 MCCB.
Looked everywhere in the regs, the NICEIC Technical manual, just about tried everywhere else

 

[RF Lighting]

What rating is it?

 

[mark64]

'A' Type

 

[RF Lighting]

We need the current rating.
Also is it SP or TP? (not sure it this makes a difference though)

e.g. A 16A MCCB will have a higher permitted Zs than a 160A MCCB

 

[mark64]

From what i know, 100a, not sure if its a SP or TP rated MCCB

 

[nozspark]

A BS EN 60947 is a 2 pole isolator switch not a MCB

 

[mark64]

i agree its a switch but do you have any idea what the maximum Zs value would be?

 

[pdcelec]

why?

 

[RF Lighting]

A BS EN 60947 is a 2 pole isolator switch not a MCB

Not quite.


A BSEN 60947-3 device is an isolator.

A BSEN 60947-2 device is an MCCB.



BSEN 60947-2 MCCBs (in a SquareD panel board)

BSEN 60947-3 Main Switch (In a domestic consumer unit)

 

[securespark]

I think you're mixing up Zs & Ze.

There are maximum EFL (Zs) values depending on disconnection times & CPD values & types.

For a switch disconnector, you must be thinking of Ze, the incoming supply loop value.

These are:

TN-C-S (PME) = 0.35

TN-S = 0.8

TT = max. 200 (or 100 if NICEIC)

 

[mark64]

I managed to get an answer.
I contacted Hager directly this morning, and was informed that BS60947-2 (switch disconnector) does not have a maximum Zs value. It is only a switch, in the event of a fault it will not trip.

Many thanks for everyone's help

 

[securespark]

That is conflicting advice.

-3 is a switch disconnector.

-2 is a circuit breaker

as defined in BS7671. It is referenced to Reg: 413-02-11 & 14 & Appendix 4, which suggests -2 is NOT a switch disconnector.

Are you sure the suffix is -2?

What else does it say on this "switch"?

 

[Doodley]

I think you're mixing up Zs & Ze.

There are maximum EFL (Zs) values depending on disconnection times & CPD values & types.

For a switch disconnector, you must be thinking of Ze, the incoming supply loop value.

These are:

TN-C-S (PME) = 0.35

TN-S = 0.8

TT = max. 200 (or 100 if NICEIC)

Where did you get this information? Maximum Ze permitted for a TT system is 21ohms. And as the impendance cannot be guaranteed (soil resistivity changing) a 300mA time delayed RCD should be installed at the intake point of TT systems

 

[Taylortwocities]

Where did you get this information? Maximum Ze permitted for a TT system is 21ohms. And as the impendance cannot be guaranteed (soil resistivity changing) a 300mA time delayed RCD should be installed at the intake point of TT systems

Dooley, you are very wrong. Where did YOU get this information??

Go read Table 41.5 and tell me where the 21 ohms comes from.

In a TT system (now) all circuits will be protected by 30mA RCD so 1667ohms is the max to ensure RA x In <50V

Where on earth (excuse the pun) does a 300mA S-type RCD come from?

 

[RF Lighting]

IIRC they are only normally used for protection against fire.