A communications provider proposes attaching an aerial drop to the same service mast that supports the electric service-drop conductors. How does the Code treat that?
- AIt is permitted where the attachment is at least 12 inches below the electric service conductors
Clearance below the electric conductors is a separate concern and does not create permission. The restriction is on what may be attached at all.
- BIt is permitted where the mast is trade size 2 rigid metal conduit or larger and is guyed
Mast size and guying address strength, which is the other half of the rule. Even a heavily guyed mast may not carry a communications drop.
- It is not permitted; only power service-drop or overhead service conductors may be attached to a service mast
- DIt is permitted where the communications drop is bonded to the intersystem bonding termination at the meter enclosure
Bonding a communications system to the intersystem bonding termination is required for other reasons and has nothing to do with mechanical attachment to the mast.
Why C is correct
The mast rule has two parts: the mast must be strong enough for the load imposed by the service drop, including any guying required, and nothing other than power service-drop or overhead service conductors may be attached to it. The second part is the one that answers this question, and it does not depend on the mast size or on where the attachment lands.
What this question is testing
The item tests whether the candidate knows a narrow, absolute restriction and can separate it from mechanical strength requirements and from grounding rules that also mention the mast area.
On the job
This argument happens on the roof, with two crews on site. The communications installer wants the mast because it is the only solid point on that gable, and the homeowner does not care who wins. The correct answer is a separate attachment point on the structure, which the communications article addresses. Masts that end up carrying two drops eventually pull out of the roof, and the electrical contractor owns the resulting leak and the reinstallation.
Memory technique
The mast belongs to the power drop and nothing else.
Exam tip
The service mast rule is short and absolute. Read the whole section, since strength and attachment are two different requirements in it.
Where to look it up
Look in the services part covering overhead service conductor installation, at the section on service masts used as supports.