Following a recent conversation at a moth night and a comment on an email group I got to wondering how much it actually costs to run a moth trap overnight.
The formula is quite simple to use as long as you know the cost of a unit (kWh) of electricity. If the following is not correct then let me know, my physics is a bit rusty.
Cost = power of lamp in kW x kWh cost x number of hours
Assuming a unit cost of 15p per kWh (which is a little on the high side but will depend on your supplier/tariff.
Cost of a 125W MV lamp per hour = .125 x 15 = 1.875 pence per hour
Cost of a 40W actinic per hour = .04 x 15 = 0.6 pence per hour
Cost of a 15W actinic per hour = .015 x 15 = .225 pence per hour
The following table summarises approximate costs for a range of running times. Values are rounded to nearest 0.5p
|125W MV||40W actinic||15W actinic|
|Cost for 8 hours||15p||5p||2p|
|Cost for 10 hours||18.5p||6p||2p|
|Cost for 12 hours||22.5p||7p||2.5p|
Personally I’ll continue splashing out the higher cost for the MV the extra moths are worth the expense .