I am looking at a job where I will be driving nails into the apex of a roof to secure roof anchors. My concern is accidentally hitting an electrical line on the underside of the roof. Is this an unwarranted concern given electrical codes and/or standards? On every youtube video and home improvement show the roofers drive nails into the roof as if there were no chance of striking an electrical line on the other side. Left to my own devices, I would probably at least use a non-contact voltage tester (such as the one made by Klein Tools).
Electrical – Safely Driving Nails Into Roof
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The plywood of your roof is typically not as thick as your standard galvanized steel roofing nail, so it is expected for nails to show through this in your attic. The plywood can and is expected to take a bit of damage over time and this is okay as long as the shingle has something firm to hold itself down onto.
Over time if the plywood is too damaged to properly hold down new shingles or becomes too dangerous to walk on safely then a roofer should be able to identify such compromised plywood board and replace it as needed.
What is worrying about your question is that you specified that the roofing nails have split and damaged the roof trusses. Standard roofing nails should not be long or thick enough to split or crack structurally sound dimensional lumber.
If this is what happened then you may have a problem unrelated to the quality of the roofing job. Your home is over 50 years old in a warm wet climate, so you should inspect for a number of different problems.
Dryrot
Termites
Carpenter Ants
If you have any of the following indications of current or past damage to any of the three items then that would explain split, cracked or damaged roof trusses during a typical roofing job.
On another note: The soffit typically fits into a groove that is known as J Channel when installed on a roof overhang. The roof overhang is typically MUCH too tall for any roofing nails to reach soffit. I imagine instead you might be seeing a roofing nails perforating the fascia, which can be a sign of a sloppy rushed job. Without pictures though we can't tell that for sure.
You wear a harness attached to a rope that is thrown over the roof and tied to something solid such as a tree.
The harness kit may look like this:
The harness is most often used in a manner as shown here. A short connecting rope goes from the middle of the high back over to a D-Clip that then attaches to the main safety rope via a Robe Grab.
Rope grabs come in various styles (one shown below) but are basically designed to permit them to slide along the rope when they are directly pushed but will clamp tightly on the rope when pull tension is applied to the connecting ring from the D-Clip and short rope to the roofer.
This picture shows a harness in use on a roof....albeit not quite as steep as the OP has asked about.
Here is another in use application.
Best Answer
Typically if there are any wires in the attic attached to the roof framing, they will be on the underside of the rafters well separated from the surface you are planning on installing the roof anchors.
The only wires I could ever think would be of concern are wires that would run to an attic light. They will be attached to the sides of the rafters well below where nail points will be that you will be driving. All other wires would be in the ceiling joists for room lighting, etc.