Heaters on One line diagram

[vds002]

I have couple of 1.1 MW, 480 V heaters that I need to show on single line diagram. What symbol should I use. Can I just use a box and write Heater in it. Or Should I draw a box and write SCR controller in it and connect a circle to it and write 1.1 MW heater in it.
Any suggestions...

 

[rcw retired EE]

I'd draw two boxes, one for the SCR and one for the heater. The one line can show the power feed cables to the SCR controller and from the controller to the heater. That will help who ever has to size and account for power cables.

If the heater and controller are all one device, just use a single box.

At 1 MW+ the heater is probably made up of several smaller heating elements and multiple SCR's in the same panel. Instead of 1 set of large wires from the controller you may have 3, 4, or 5 sets of smaller wires.