Re: So, what are some warning signs that a stage may be unsafe?
I never claimed it was "about color" just that the color typically indicates the wrong type of cord per code. Thermoplastic most certainly does have other implications, typically made from PVC, other things to consider are fire ratings and the toxic fumes it gives off if (when) it vaporizes.
FWIW, I think the 2011 NEC doesn't make exception for using Junior grade cable anywhere anymore... It's all gotta be extra-hard now. Someone correct me if I'm wrong on that.
While the W indicates that it's suitable for wet locations and is sunlight resistant. Whether that is required for stage use outdoors I don't know. I've seen plenty of SO and SOO used outdoors and NEC 2011 Table 400.4 specifices SO and SOO are suitable for "damp locations." What is the difference between damp and wet? Judgement call, but go with SOOW to be safe. Note 6 specifically says: "Types G, G-GC, S, SC... SO, SOO... etc." are permitted for use on theater stages in garages and elsewhere were flexible cords are permitted by this Code."
