230.205(B)

[m sleem]

(B) Type. Each service disconnect shall simultaneously disconnect all ungrounded service conductors that it controls and shall have a fault-closing rating that is not less than the maximum short-circuit current available at its supply terminals.
Where fused switches or separately mounted fuses are installed, the fuse characteristics shall be permitted to contribute to the fault-closing rating of the disconnecting means.

Does this mean, fuse rating shall protect the disconnecting mean rating ?

 

[m sleem]

What i meant here, the fuse rating shall be less than disconnecting mean rating. Any feedback!

 

[jap]

Disconnects are rated by horsepower and Amperage.

The fuse holders are designed as to not allow a larger "Amperage" fuse than the disconnect is rated for to be installed.

That sentence above is not talking about the "Amperage" rating of the disconnect, it's talking about the "Fault Closing Rating" of the switch itself.

For example, if a service is calculated at max 22k, then the Fault Closing rating of a non fused switch must be "Fully" rated at not less than the full 22k.

If a "fused" disconnect is used, the "Series" rating through a fuse of the correct type, may allow you to use a disconnect that does not have to be "Fully" rated at 22k.

JAP>

 

[m sleem]

Disconnects are rated by horsepower and Amperage.

The fuse holders are designed as to not allow a larger "Amperage" fuse than the disconnect is rated for to be installed.

That sentence above is not talking about the "Amperage" rating of the disconnect, it's talking about the "Fault Closing Rating" of the switch itself.

For example, if a service is calculated at max 22k, then the Fault Closing rating of a non fused switch must be "Fully" rated at not less than the full 22k.

If a "fused" disconnect is used, the "Series" rating through a fuse of the correct type, may allow you to use a disconnect that does not have to be "Fully" rated at 22k.

JAP>

Thanks Jap,

I think LBS refers to a device in which disconnect the load manually and doesn't have a trip automatic unit.