Gray is a pretty universal primer color. Since paint doesn't qualify as corrosion protection, they just want to cover everything with a surface that will likely be painted anyway. A $3 can of spray paint and a little masking tape will give you about any shade you want. Service entrance equipment can be made to almost disappear if painted the same color as the house. I've always been suprised by people who do a nice job on the load center in the pantry and leave all that ugly gray stuff on the outside wall.
