Isolation on sensor lights.?

[bigspark17]

Hi guys, whats your opinions on isolation of sensors/lighting arrangemant with following scenario all in a domestic situation only?
1-proximity sensor in hallway or landing?
2-outside pir light?
3-door switch in a cupboard?
must there be a switch or key switch or can the sensor have a permanant feed of the ocpd?

thanks replies welcomed

 

[Pete999]

Hi guys, whats your opinions on isolation of sensors/lighting arrangemant with following scenario all in a domestic situation only?
1-proximity sensor in hallway or landing?
2-outside pir light?
3-door switch in a cupboard?
must there be a switch or key switch or can the sensor have a permanant feed of the ocpd?

thanks replies welcomed

Which light/lights are you intending to switch on and off??

 

[Andy78]

I'm sure there is something in building regs about outside pir lights over a certain wattage requiring isolation for energy conservation purposes......

 

[bigspark17]

1- occupancy sensor in hall switches light in hall.
2-outside pir switches outside light.
3- door switch in cupboard doorframe switches light in cupboard.

 

[Andy78]

Are you asking if BS7671 requires that circuits must have isolation before methods of automatic switching ?

 

[bigspark17]

Yes in the three situation above?

 

[Andy78]

Not that I'm aware of as a general rule, but it may be good practice in lots of situations I could think of.
That said, I have designed many circuits to have overrides and isolation where automatic switching is involved, and also fitted many circuits as such when working to specification. I could probably count the number of automatically switched circuits I've fitted in the last few years on one hand though.

I'm happy to be corrected if I'm wrong though.

What brings this question up ?

 

[westward10]

I don't think they do. I have seen many commercial installations where motion sensors have been retrofitted. Sometimes the existing switches are just taken out of circuit or sometimes they are replaced with key switches. I would guess key switches were fitted because it was just an easier option. Andy may have a point about the outside light with regards to Building Regs but I don't know, would Building Regs apply.

 

[Octopus]

Good practice would be to fit an isolation switch to all fixed loads, so when the RCD trips you can turn them off.

Just saying