Symbol 3773 from ISO 7000 - Title/Meaning: Main shut-off control Function/description: To identify the main shut-off control of a power source.
pay attention to orientation of symbolAdditional information: 
If the shut-off is for electrical power only, use IEC 60417-5008
This symbol may be used in conjunction with other symbols, for example, by inserting an appropriate functional symbol within the rectangle outline shape
Own work using: iso.org/obp/graphics/grs/c0b0aa68-11f9-4478-bef5-34c4c8ea28a8 200.png
Vectorization:  Mrmw