Design current?

[pc1966]

But what about the current the permanent live would draw at every other light for its emergency fitting

Would that need to be calculated as well?

In theory, yes.

In practice, no.

Normally the permanent live is likely to be a fraction of the normal service current so can be largely ignored. Typically lights take many more hours to charge then to discharge, and even then (emergancy light power) they are typically at much less than full design power.

 

[Lucien Nunes]

Also, as a rule, one does not need to look into every watt of load and metre of cable. Assess the load, assess the midpoint, if it looks like it's well within limits forget about it thereafter. Only if the cable is very long or very expensive, and the load known accurately, and the drop right on the borderline between being OK and needing the next cable size up, would it repay very detailed investigation. Most VD calcs take me about 10 seconds per circuit.

The kind of lighting loads where one really does have to account for every fitting are 400W high-bay SON floods in rows along a 200 metre warehouse. In this situation, VD is likely to be the determining factor. Assorted emergency fittings around an office, not so much.

 

[Newtothis]

Also, as a rule, one does not need to look into every watt of load and metre of cable. Assess the load, assess the midpoint, if it looks like it's well within limits forget about it thereafter. Only if the cable is very long or very expensive, and the load known accurately, and the drop right on the borderline between being OK and needing the next cable size up, would it repay very detailed investigation. Most VD calcs take me about 10 seconds per circuit.

The kind of lighting loads where one really does have to account for every fitting are 400W high-bay SON floods in rows along a 200 metre warehouse. In this situation, VD is likely to be the determining factor. Assorted emergency fittings around an office, not so much.

Thanks for the replies everyone, had covid related issues so i wasn't able to reply 0.o

a little off topic but it goes along with the design off a lighting circuit would this be an acceptable way to run a circuit ? using something like this?

Scolmore 4 POLE CLICK FLOW CONNECTOR CT202C

The Scolmore CT202C is a 4 Pole Click Flow Pull Apart Connector. The CT202C helps to increase the load handling to 20Amp in lighting installations.

www.superlecdirect.com

cable basket with click flow connectors? I have seen it done like that above a load of false ceilings.

sometimes with the click flow connectors and sometimes with the klik plugs