Terminal blocks - no fusing down?

Zoomup: 
 Fusing down to protect a cable from overload is normally a wise thing to do. This will protect a cable from getting too hot and being damaged if a large overload current occurs. But if the load is fixed in value, say like a single heater, it can not overload a cable as it uses a fixed amount of current.  So in some instances we are just concerned about a large fault current, which is different to an overload current. 

If a load is of undetermined value, say by supplying sockets, anything may be plugged into those sockets and we would be wise to provide overload, or overcurrent protection for the supply cables. We do this with a ring final circuit protected by a 32 Amp device.

But larger cables supplied from a bus-bar chamber will be protected by a fuse or circuit breaker down stream of the connection to the bus-bars, even if the cable reduction occurs before the downstream fuse or M.C.B. The cables are protected against overload as if an excess current flows the fuse will blow, or the circuit breaker will open, thus protecting the upstream cables.

 

Z.

 

 

Precisely, my thinking is that fusing down should protect lower gauge wire feeding other circuits.  In the same way when carrying out a PAT, you would typically replace a plug fuse attached to a figure 8 flex for 5A or 3A.

Zoomup: 
 Fusing down to protect a cable from overload is normally a wise thing to do. This will protect a cable from getting too hot and being damaged if a large overload current occurs. But if the load is fixed in value, say like a single heater, it can not overload a cable as it uses a fixed amount of current.  So in some instances we are just concerned about a large fault current, which is different to an overload current. 

If a load is of undetermined value, say by supplying sockets, anything may be plugged into those sockets and we would be wise to provide overload, or overcurrent protection for the supply cables. We do this with a ring final circuit protected by a 32 Amp device.

But larger cables supplied from a bus-bar chamber will be protected by a fuse or circuit breaker down stream of the connection to the bus-bars, even if the cable reduction occurs before the downstream fuse or M.C.B. The cables are protected against overload as if an excess current flows the fuse will blow, or the circuit breaker will open, thus protecting the upstream cables.

 

Z.

 

 

Precisely, my thinking is that fusing down should protect lower gauge wire feeding other circuits.  In the same way when carrying out a PAT, you would typically replace a plug fuse attached to a figure 8 flex for 5A or 3A.