How do I make fog show when a certain amount of values are on?

I am trying to make generators for a thing I'm making, and once they're all off I want the fog to appear so it's difficult to see. I have two scripts, one to turn it on and off.

I am a noob at scripting, so please go easy on me!

if 
	workspace.LightSwitch1.ValueR = true
	and
	workspace.LightSwitch2.ValueE = true
	and
	workspace.LightSwitch3.ValueF = true
	and
	workspace.LightSwitch4.ValueD = true
	then
	wait(2.5)
	script.parent.PowerOut.Play
wait()
	game.Lighting.FogEnd = ("50")
end

And

if 
	workspace.LightSwitch1.ValueR = false
	and
	workspace.LightSwitch2.ValueE = false
	and
	workspace.LightSwitch3.ValueF = false
	and
	workspace.LightSwitch4.ValueD = false
	then
	wait(.5)
	game.Lighting.FogEnd = ("999e999")
end

if 
    workspace.LightSwitch1.ValueR = true
    and
    workspace.LightSwitch2.ValueE = true
    and
    workspace.LightSwitch3.ValueF = true
    and
    workspace.LightSwitch4.ValueD = true
    then
    wait(2.5)
    script.parent.PowerOut:Play()
wait()
    game.Lighting.FogEnd = 50
end

if 
    workspace.LightSwitch1.ValueR = false
    and
    workspace.LightSwitch2.ValueE = false
    and
    workspace.LightSwitch3.ValueF = false
    and
    workspace.LightSwitch4.ValueD = false
    then
    wait(.5)
    game.Lighting.FogEnd = 999999
end