Load Break Switch & Fused Cut out

[tin2779]

Please correct me if I am wrong.

In case of distribution voltages up to 25 KV, utilities use fused cut outs for pad mounted transformer or lateral tap switching. But after 25 KV, A standard load break switch or disconnect is required to do the same job ?

I am sure, utilities dont have to abide by local Electrical safety authority regulations. But, Will a fused cut out at 13.8 KV for a commercial premises can act as a means of disconnect or we need to provide a three phase disconnect.

I will be talking to local electrical inspector but dont want to be completely dumb about the trend of these kinds of installations.

I would appreciate, if you guys could advise.

Thanks

 

[dpc]

It depends on the installation. Cut-outs are not used exclusively below 25 kV. Most typically used for overhead distribution systems. But many pad-mount transformers also include fuses under the oil for additional protection.

But if your question concerns meeting NEC requirements for main service disconnect or adequate disconnecting means, it is all irrelevant because owners cannot rely on utility-owned switches, fuses, etc to satisfy NEC requirements.

 

[steelerfan28655]

Fused cutouts will protect the utility system from fault currents on your side of the fuse. They are also for protection of the conductor from the tap to the transformer.

Unless you are willing to pay for a recloser, or some form of automated disconnect switch with fault sensing capabilities, the fused cutouts are your best bet.

Is this a service that you are planning on having disconnected - reconnected frequently? or under load?

If you will be doing switching under load, then fused cutouts are not the best option.

Happiness is a way of travel, not a destination.

 

[steelerfan28655]

Our standard practice is to use fused cutouts for most industrial/commercial facilities.

My system is 12,470Y/7200 and we do not typically use switches unless the customer has special needs/requests.

The utility safety code is the NESC, IEEE, ANSI, OSHA, and any other federal agency that decides it wants a piece of the action.

The NEC, and most local inspectors jurisdiction, starts at the point of metering.

Is you utility providing the transformer?

Happiness is a way of travel, not a destination.