Twin and Earth CPC

[Cookie]

IEC 60364-5-54 states that phase conductors 16mm2 and smaller require a CPC of the same size, over 16 to 35mm2 a 16mm2 CPC and over 35mm2 a half size CPC is required.

My questions is why am I seeing catalogs with harmonized twin and earth with reduced size CPCs over 2.5mm2? And why doesn't the half size rule kick in when wire is over 4mm2 instead of 16mm2?

 

[Mark Wright]

Hmm not sure there are several American web sites on the subject and I'm not sure it's wrong

Two examples

1) A Metal case appliance has a fault -Line to the metal case you touch this you are the path to earth through you feet, what happens?

2) A Metal case appliance has a fault -Line to the metal case, but the case is earthed.
You touch this - does electricity flow throw you to earth or does it take the path of least resistance the the Earth\CPC ?

 

[Cookie]

Hmm not sure there are several American web sites on the subject and I'm not sure it's wrong

Two examples

1) A Metal case appliance has a fault -Line to the metal case you touch this you are the path to earth through you feet, what happens?

2) A Metal case appliance has a fault -Line to the metal case, but the case is earthed.
You touch this - does electricity flow throw you to earth or does it take the path of least resistance the the earth?

The path of least resistance is the main bonding jumper. Earth has nothing to do with opening a breaker or fuse.

 

[Mark Wright]

anyone else on the above scenario?

and there is no protective device
hypothetical scenario
- only talking electric shock with contact with the metal case.

 

[DPG]

The path of least resistance is the main bonding jumper. Earth has nothing to do with opening a breaker or fuse.

Cookie, could you clarify what you mean here.

 

[Cookie]

Cookie, could you clarify what you mean here.

Here is a visual describing the terms from NEC land:

The main bonding jumper is a wire, screw or busbar which connects the equipment ground bar to the neutral bar in the main service equipment. It is mandatory under the NEC as TT earthing is not allowed. The majority of fault current will travel through the bonding jumper onto the neutral bar returning via the utility neutral.


System bonding jumper is a term used for separately derived systems like a transformer or generator.