Wat the heck is...

[bushynut]

Ok, I'm doing canble calculations as revision for my forthcoming exam, I've lost pretty much all of my notes due to my ex binning them by accident, anyhow please help if you can with the following

3 x 400watt SON/ I High Pressure Sodium Lmps mounted on 5m concrete columns each fitted with a SP & N fused cut out in the column base.

My problem is and it might be 'cause I'm not thinking straight but what is a

SP & N fused cut out?

and is there any calcs/ factors I should take into account for street lighting? for doing cable calculations. This isn't for an assignment this is purely revision and I had the note I lost the notes, and I could do with some help. Thanks in advance

 

[RF Lighting]

what is a SP & N fused cut out?

It is a single pole and neutral fused cutout (i.e. a fuse in the live conductor only)

is there any calcs/ factors I should take into account for street lighting? for doing cable calculations.

You will need to add an additional load per fitting for the ballast power (multiply lamp wattage by 1.8 and divide by supply voltage (thanks to spark123 for that)

 

[breezer]

i was thinking more along the lines of double pole isolator since it said sp & N (single phase AND neutral)

 

[bushynut]

would the ballast factor which would be in wattage be needed to be added onto the total wattage in the calculation for Ib?

Thanks

 

[RF Lighting]

SP & N fused cut out?

I have worked on street lighting with a cut out which is basicly a mini version of an REC cutout (usually found on highways agency street lighting) and street lighting with a D.P. switched spur in the bottom of the coloumn (usually in private car parks such as shopping centers)

But i would have thought it would specify D.P. if this were the case. IIRC my college assignments were worded very specifically.

would the ballast factor which would be in wattage be needed to be added onto the total wattage in the calculation for Ib

Yes. This will then give you a 'fitting wattage' rather than a 'lamp wattage' from which to do your cable calcs.