Single point of failure.

[kai]

Why is it a single point of failure is still allowed in an installation?

I am referring to the main service fuse or "cut out" fuse, if that operated, the entire installation will go off, and house plunged into darkness.

Something to think of...

 

[JonoPashley]

If you manage to blow the main fuse then there is a issue which is of such magnitude that total power loss becomes irrelevant.

 

[FourFootMedia]

EM lighting. Problem solved. Especially with the popularity of 12v downlights, it's extremely easy to convert one fitting with an EM pack to provide some light throughout the house. The only room in our house now without some form of EM lighting is the pantry.

 

[ericmark]

Looking at 314 it says "produced by equipment in normal operation" when listing why we need to split an installation into circuits.

Under normal operation you will not blow the main incoming fuse.

As to safety circuits if danger is present due to power failure it would not matter if whole street lost power or only your house and the only way you can protect against that is to have some form of back-up power.

Back-up power comes in many forms. I have a gas fire which is never used but there in case of electric failure to heat house as central heating needs electric for pumps. I could just as easy fit a UPS to power boiler.

Lighting also comes in many forms from re-chargeable torches which auto switch on with power cut. To a small pull cord battery powered light or full 3 hour emergency lighting or candles and a box of matches.

The real problem we face today is the tripping of RCD's with no apparent fault. After many years trouble free I am now getting problems and I suspect the freezer as it switches to de-frost cycle.

The only cure is to do away with twin RCD's and fit multi-RCBO's instead. With the number of items which have filters now this is only way out. But there is a big difference here to main incoming fuse.

The RCD trips when there is no fault but the fuse only blows when there is a fault if the amount of electronic equipment with filters continues to increase I think we may need to do away with two ring mains and have 4 radials instead but in spite of many houses being able to draw well over the main incoming fuse rating I have only come across blown fuses where something very wrong had happened.

 

[ColJack]

expanding on your thought Kai, if the substation at the end of the street blows up, you've lost the whole street..
the pylon carying the 11KV gets blown over in a gale...
the nuclear power station melts down..

at some point, you're going to have a single point of failure..

a service fuse is unlikely to blow unless something is majorly wrong, or you've designed an installation that is over spec for the size of fuse you have..

 

[Chri5]

The human body is pretty carp, only 1 x heart- stupid designer

 

[NotHimAgain]

ericmark said:

"produced by equipment in normal operation"

No you can't get away with that one .

You have taken part of a sentence from one clause 314.1 (iv) and then applied it to the whole regulation. In fact it only refers to the normal operation of RCDs.