Describe electrical network in guide

guide.lua

@@ -26,6 +26,30 @@ local pages={
 				IndustrialTest implements finite power functionality which can be used to perform various tasks using generators and consumers. Such features are not a new thing in Luanti, as there are older mods which do that already. This mod, however, proves to be more flexible.
 			</left>
 		]]
+	},
+	electricalNetwork={
+		title=S("Electrical network"),
+		icon="industrialtest:insulated_copper_cable",
+		content=[[
+			<big>Electrical network</big>
+			<left>
+				In order to attach electricity consumers to power sources (like generators, batteries, further just called generators) electrical network is used. Consumers can get connected either directly to generators or through various cables. Each generator can output certain voltage (this is actually amperage, however since this mod doesn't simulate electricity accurately, it's called voltage), the same situation is for consumers as they can only handle up to certain voltage.
+				Figure 1 shows voltage levels present in this mod.
+				If voltage is too high for cable it will melt without dropping anything while consumer will explode also without dropping anything and possibly destroying terrain around. Power capacity is measured in EU (Energy Units) and the voltage is EU/update.
+			</left>
+			<mono>
+				--------------------------------------------
+				| Voltage level | EU/update  | Cable       |
+				--------------------------------------------
+				| LV            | 600        | Tin         |
+				| MV            | 2400       | Copper      |
+				| HV            | 10200      | Gold        |
+				| EV            | 40800      | Iron        |
+				| IV            | 163800     | Glass Fibre |
+				|----------------------------|--------------
+				Figure 1. Voltage levels and respective cables
+			</mono>
+		]]
 	}
 }