Presuming this is connected to your previous thread, you may need to maintain a factor of safety of 2 per OSHA 1926.502(d)(15)(i) (presuming it would be classified as a Personal Fall Arrest System).
If OSHA doesn't apply, 1.5 is the typical factor of safety against structural overturning. I'm not aware of it being directly codified, except through the load combinations used to check against overturning (e.g. 0.6D + W). You would also be able to find it referenced in your foundations text.