I am writing an excel formula that will work out how many light fittings (each drawing 0.9W) will be required for any length of detail and also the number of drivers. The user enters say 1m which the calculation works out to require 6 light fittings.

I then want to work out how many drivers this will require. The driver can run upto an 18W load so for a 1m length with each light fitting drawing 0.9W I want the calculation to return a value of 1 (as this is the minimum driver required). If the user enters 15m then 86 light fittings are required with 4 x 18W drivers being required as the total load of 86 fittings is 77.4W.

Can anyone tell me how to write a formula that will automatically calculate how many drivers are required?

I hope that makes sense, I have read it through a couple of times to check!

for the drivers required use thr roundup function

“=roundup(x/18,0)” where x is your required load

btw 77.4W requires 5 drivers 🙂

Your correct on the 5 drivers! Thanks for the formula

One more question… 😳

Is it possible to format a cell so that whatever answer the formula gives it will be followed by a W?

select cell

Format>cells>

[Number] Tab

select “Custom”

type
0″W”

into box on top right.