11.2 Services & Service Equipment

11.2 Services & Service Equipment

What Is a "Service"?

A service is the set of conductors and equipment that deliver electrical energy from the serving utility — Meralco or a local electric cooperative, depending on the franchise area — to the wiring system of the premises being served. A service begins at the service point, the point of connection between the utility's facilities and the premises conductors, and ends at the service disconnecting means, the first point in the building where the entire electrical system can be shut off. Everything downstream of the service disconnect is feeder and branch-circuit wiring, covered under the rules discussed in the previous section; everything the RME does at the service itself — sizing, clearances, disconnect count, grounding — is governed by its own set of provisions because a mistake here affects the whole building at once, not just one circuit.

Service Drop vs. Service Lateral

Utility conductors reach a structure by one of two physical routes:

A service drop requires an adequate point of attachment — often a service mast, discussed below — and must clear the ground, driveways, and building openings by set margins. A service lateral trades those overhead concerns for underground ones: conduit or cable must be protected from physical damage, buried at adequate depth, and terminated so moisture cannot track into the service equipment.

Service-Entrance Conductors

Service-entrance conductors run from the service point (or, for a lateral, from the underground termination) to the service disconnecting means. Their ampacity must never be less than the rating of the service disconnect they feed, and their size is derived from the building's calculated demand load — never simply guessed from the size of the existing wire being replaced.

Worked example. A dwelling unit has a calculated demand load of 9,200 VA at 230 V single-phase.

• Calculated load current = 9,200 VA ÷ 230 V = 40 A
• The next standard overcurrent device size at or above 40 A is 50 A — that becomes the main breaker rating
• From the branch-circuit conductor table in the previous section, 14 mm² copper THHN supports roughly 55 A, comfortably covering the 50 A main, so 14 mm² is the minimum acceptable service-entrance conductor size for this dwelling

This calculate-then-round-up-then-verify-conductor sequence is the core competency the RME exam is testing when it asks about "minimum service size" — it is never a single table lookup, but a short chain of three steps.

Number of Services per Building

The general rule is that a building or structure is supplied by only one service. Multiple services complicate fault-current coordination, make it harder to fully de-energize a structure in an emergency, and confuse metering and billing. PEC recognizes a short list of situations where more than one service is allowed, including:

• Fire pumps, which must remain powered independently of the building's normal service
• Emergency and legally required standby systems that need a separate, reliably available source
• Multiple-occupancy buildings specifically designed for separate utility connections — for example, a commercial strip with individually metered tenant units, or a townhouse row where each unit is intended to have its own utility account
• Buildings whose calculated load exceeds what a single service of practical size can carry

An RME should treat these as narrow, code-recognized exceptions, not as license to run a second service purely for owner convenience.

Service Equipment Components

Service equipment is made up of three functional pieces, whether housed in one combination enclosure or several adjacent enclosures:

1. Main disconnecting means — the main breaker or switch that can open all ungrounded service conductors at once; it must be readily accessible and clearly marked as suitable for use as service equipment.
2. Metering equipment — the utility's revenue meter and meter base/socket, positioned per the local utility's metering rules, ahead of or integrated with the main disconnect.
3. Main overcurrent device — sized to the calculated demand load and coordinated with the ampacity of the service-entrance conductors, as worked through above.

Number of Disconnects at a Service

Rather than requiring a single main breaker in every case, PEC allows the service disconnecting means to be made up of up to six individual disconnects — switches or circuit breakers — provided they are all grouped at one location and each one is permanently marked to identify the load it serves. This is common in small commercial buildings: instead of one large main breaker feeding a distribution panel, the service can terminate directly into as many as six smaller breakers, each dedicated to one tenant space, one HVAC unit, or one major load, as long as the grouping does not exceed the six-disconnect limit and all of them are installed together at one location.

Service Clearances

Clearance rules exist because service conductors, unlike branch-circuit and feeder conductors, are not fused or protected until they reach the service disconnect — they are energized continuously from the utility side. Three clearance zones matter most for an RME:

• Vertical clearance above grade — service-drop conductors must clear finished grade, sidewalks, and especially vehicular areas such as driveways and roads by a greater margin than they need over purely pedestrian areas, because the risk of contact from a raised vehicle or equipment is higher.
• Clearance from windows, doors, porches, and balconies — conductors must be kept out of reach from any opening a person could lean or reach through, so ordinary building use never puts an occupant within reach of an unprotected, always-energized conductor.
• Clearance from swimming pools — overhead service conductors need generous horizontal and vertical clearance from pool edges, diving structures, and any elevated pool deck, because people around pools routinely handle long metal or wet objects, such as skimmer poles, that can bridge an otherwise-safe distance.

Service Mast

Where roof height or obstructions require raising the point of attachment above the roofline, RMEs use a service mast — a rigid raceway extended upward to create an adequate attachment point for the service drop. Because the utility's conductors physically pull on the mast, it must have real mechanical strength — rigid steel conduit rather than thin-wall tubing — plus adequate bracing or guying back to the structure so the point of attachment cannot bend, twist, or pull loose under wind or storm loading.

RME Field Scenarios

Upgrading an old fused service. A common renovation job is replacing an aging 30 A fused residential service — rewireable fuses in an old panel board — with a modern 60 A circuit-breaker main. The RME does not simply swap the enclosure: the calculated demand load is recalculated first, since the household likely added air-conditioning, an electric water heater, or other loads since the original installation; the service-entrance conductor ampacity is verified against the new breaker rating; the grounding electrode system is checked against current requirements; and the overhead clearance at the existing point of attachment is reconfirmed if the mast or attachment height was not changed.

Small commercial strip. Five tenant units sharing one utility transformer can be designed either as one larger service with tenant sub-metering fed from a downstream distribution panel, or — where the six-disconnect grouping rule is satisfied — as up to six grouped disconnects at the service itself, each sized to its own tenant's calculated load. The choice affects both first cost and how independently the tenants can be isolated from one another electrically.