Six service disconnects are still permitted, and six handles in one panelboard are still the wrong answer

Where services sit on the paper

The PSI content outline gives services, service equipment and separately derived systems 6 of the 56 scored items on the journeyman NEC Knowledge portion, and services and separately derived systems 4 of the 24 scored items on the Calculations portion. On the calculations half that ties services with branch circuits for the largest single block, and it is double what feeders carry.

One level up the weighting climbs. On the master calculations portion services carries 8 of 30 scored items, so this reading keeps paying if you go on to the master examination after the two years holding a journeyman license that Tex. Occ. Code 1305.153 requires.

Our 500-question bank runs the same way. Ninety-two of the 500 questions mention a service somewhere, and they concentrate in grounding with 33 and installation knowledge with 32, with 20 in the load calculation area. A service item is very often a grounding item wearing a service stem, which is worth knowing before you decide which article to open.

In fiscal year 2025 the journeyman calculations portion passed 1,301 of 6,328 candidates, each portion scored separately at 70 percent, and a retake costs $78 whether you lost one portion or both.

How many disconnects, and what counts as one

Each service gets one service disconnecting means, except where NEC 230.71(B) permits more, and that subsection permits two to six.

The part that decides items is the arrangement. Every permitted one has the same shape: a disconnect per enclosure, per panelboard with a main service disconnecting means in it, per switchboard enclosure or barriered vertical section, or per compartment in switchgear or a metering center. The arrangement most people picture, six breakers sharing one main-lug panelboard, sits outside that list.

An exception covers time. Service equipment installed in compliance with an earlier edition, when multiple disconnects in one enclosure were permitted, may keep up to six of them, which covers the panel you're standing in front of on a service change.

NEC 230.71(A) names devices outside the count: disconnecting means installed as part of listed equipment and used solely for power monitoring, for a surge-protective device, for the control circuit of a ground-fault protection system, or for operating a power-operable service disconnect. An item showing seven handles and expecting a violation is often showing six plus one of those. Grouping is a separate section, and NEC 230.72 requires the two to six to be grouped and each marked to show the load it serves.

The 2026 outdoor disconnect rule

For a one-family or two-family dwelling, NEC 230.70(A)(1) now requires the service disconnecting means to be installed in a readily accessible outdoor location, either on the dwelling unit or within sight of it.

That is a change of substance. The 2020 and 2023 editions put an emergency disconnect outdoors at 230.85, separately from wherever the service disconnect sat. In the 2026 book 230.85 is gone, the outdoor requirement is written into the location rule, and 230.70(D) picks up the identification material.

The section carries an exception tied to NEC 225.41, which is the emergency disconnect rule for a building supplied by a feeder. Read it before you call an installation non-compliant, because a dwelling fed from another structure is the case it covers, and feeders sets out how that supply is classified.

Two consequences follow for anyone working from questions written before this edition. An option pointing at 230.85 points at a section that has left the book. And an answer putting the only disconnect for a house inside the garage, which was fine for decades, is now wrong on its own terms.

The floor under every dwelling calculation

NEC 230.79(C) puts a floor under the service disconnecting means for a one-family dwelling at 100 amperes, three wire, whatever the calculation returns. One bank question lands a dwelling calculation at 84 amperes and the answer is a disconnect at 100 amperes or more, with the trap line naming the error plainly: the calculated load was treated as the answer while a separate section puts a floor under it.

Getting to that number is the other half. Services are rated in amperes, so the last step of a load calculation is dividing the volt-amperes by the voltage between the ungrounded conductors. On a 120/240 volt single phase service that divisor is 240. One bank question puts 43,200 volt-amperes in front of you for 180 amperes, and the option at 360 belongs to whoever divided by 120, which is the voltage to the neutral.

The same conversion carries the multifamily items. Summed dwelling unit loads of 300,000 volt-amperes at a 38 percent demand factor give 114,000, and dividing by 240 gives 475 amperes. House loads such as corridor lighting, laundry rooms and elevators are worked separately and added on top, so 475 is an intermediate figure. Folding house loads into the unit sum lets them take a reduction derived from dwelling unit diversity.

The dwelling load calculation page runs the whole sequence, and demand factors takes the reductions that get applied on the way.

Sizing, and why the service rules bite harder

Service-entrance conductors are sized at NEC 230.42(A)(1). Where they supply continuous loads or any combination of continuous and noncontinuous, the minimum size has an ampacity at least equal to the noncontinuous loads plus 125 percent of the continuous loads. The familiar exception applies: conductors may be sized at 100 percent of the sum where they terminate on an overcurrent device, and both the device and its assembly are listed for operation at 100 percent of their rating, with the listing attaching to the assembly.

What makes this article stricter than Article 215 is what sits ahead of the conductors, which is nothing. They are on the supply side of the service disconnect, so a fault on them is cleared by the utility's own protection, slowly if at all.

That single fact explains a stack of rules that look arbitrary until you see it.

• The unprotected run inside a building is kept short, which Article 230 does by putting the disconnect nearest the point of entrance.
• Service conductors may not pass through the interior of a building they do not serve, so running them through a crawl space to reach a detached shop is out.
• The grounded conductor is run to the service equipment even where nothing downstream needs a neutral, because it is the return path a fault needs, at NEC 250.24(D).
• Bonding at service raceways and enclosures is treated more seriously than at an ordinary feeder, and splices are restricted.

Underground service conductors have their own part of the article, and the cover depths live in Article 300. Hunting for a burial depth inside Article 230 is a minute you do not get back. Grounding and bonding carries the service side of Article 250 in full.

Clearances are a question about what is underneath

Overhead clearances are graded by the surface below the conductors and by the voltage, so identify the surface the stem describes and read the value for it.

Over a roof, NEC 230.24(A) asks for 8 feet 6 inches of vertical clearance above the roof surface, held for 3 feet in all directions from the edge, and that section carries several exceptions which is why a roof question is rarely settled by the headline number. Vertical clearance elsewhere is NEC 230.24(B), a graded list running from the service entrance itself up to conductors over a public street. Read the list, because every entry on it is a plausible answer for the wrong surface.

Two more clearances hide outside 230.24. NEC 230.9 keeps overhead service conductors 3 feet from windows that open, doors, porches, balconies, ladders, stairs and fire escapes. NEC 230.26 sets a floor on the point of attachment, which is kept at 10 feet or more above finished grade whatever the clearance tables would otherwise allow.

Two more details from the bank belong on the same tab. NEC 230.54 puts the service head above the point of attachment and asks for drip loops, with splices to the drop made below the head, so water running along a conductor has a low point to leave from. And downstream of the service disconnect, an overhead span on the premises belongs to Article 225 with its own clearances.

What else moved in Article 230

Three addresses changed, and each one is a navigation problem.

The listing rule turns up as a marking question. A panelboard marked suitable for use as service equipment is telling you the assembly is listed to serve as the service, and it arrives with what a service needs, including the means to bond the grounded conductor to the enclosure. Nothing in the marking forces the panel to be used that way. Our bank offers three wrong readings of it, including one treating it as a statement about fault current, which is a separate field-applied marking under NEC 110.24.

The worked arithmetic for service sizing sits in the question set, which answers what the code says and shows the numbers.

What to do before test day

Tab 230.70, 230.71 and 230.72 as a block. Between them they generate more items than the rest of the article, they now carry a requirement that used to live two hundred sections away, and they sit close enough together that landing on the wrong one costs a re-read.

Then add three flags. One on 230.79(C), since the 100-ampere floor is a one-line rule that decides a whole item. One on 230.42(A)(1) beside 215.4, so the service and feeder sizing rules sit together. One on 230.24, with the word surface written on it, because that is the first decision every clearance item asks for.

One instruction from the PSI bulletin governs all of this: when responding to the test questions, do not consider code exceptions or optional calculation methods unless the question specifically directs you to consider them. Working electricians lose points here, because in the field you reach for the optional dwelling method since it is faster and legal. On the paper the standard method is the answer unless the stem names the other one.

Then work it on a clock with thirty free timed questions, and check two things: whether you divided by the line-to-line voltage, and whether you remembered the floor after the arithmetic was right.

Questions people ask

Are six service disconnects in one panelboard permitted?

Only under the arrangements NEC 230.71(B) names, and six handles sharing one main-lug panelboard is outside them. Each of the two to six disconnects gets its own enclosure, its own panelboard with a main service disconnecting means in it, its own switchboard enclosure or barriered vertical section, or its own compartment in switchgear or a metering center. An exception covers service equipment installed in compliance with an earlier edition, which may keep up to six disconnects in one enclosure, so an existing panel on a service change is a different question.

Does a Texas house service disconnect have to be outside now?

For a one-family or two-family dwelling, yes. NEC 230.70(A)(1) in the 2026 edition requires the service disconnecting means in a readily accessible outdoor location, either on the dwelling unit or within sight of it. That absorbs what the 2020 and 2023 editions did at 230.85, which has left the book, with 230.70(D) picking up the identification material. An exception ties to NEC 225.41 for a building supplied by a feeder. An answer putting the only disconnect inside the garage is now wrong on its own.

What is the smallest service allowed for a one-family dwelling?

NEC 230.79(C) puts the service disconnecting means for a one-family dwelling at 100 amperes, three wire, as a minimum, whatever the load calculation returns. So a small dwelling can finish a perfectly correct calculation in the eighties and still take a 100-ampere service. That floor is a separate requirement from the calculation itself, which is why a bank question landing at 84 amperes offers the calculated figure as a distractor and the trap line records that the candidate treated the calculation as the whole answer.

Why do service conductor rules look stricter than feeder rules?

Because nothing sits ahead of them. Service-entrance conductors are on the supply side of the service disconnect, so a fault on them can only be cleared by the utility's own protection, slowly if at all. Everything else follows from that: the disconnect goes nearest the point of entrance to keep the unprotected run short, the conductors stay out of buildings they do not serve, splices are restricted, bonding is treated more seriously, and the grounded conductor is brought to the service equipment under NEC 250.24(D) as a fault return path.

How many service questions are on the Texas journeyman exam?

The PSI content outline gives services, service equipment and separately derived systems 6 of the 56 scored items on the NEC Knowledge portion, and services and separately derived systems 4 of the 24 scored items on the Calculations portion. On the calculations half that ties services with branch circuits for the biggest block. On the master calculations portion the count rises to 8 of 30, so this material carries more weight at the next license level than it does at this one.

Should I use the optional dwelling calculation method on the exam?

Only when the question tells you to. The PSI bulletin instructs candidates not to consider code exceptions or optional calculation methods unless the question specifically directs them to. In the field the optional method at NEC 120.82 is faster and perfectly lawful where its conditions are met, which is why working electricians reach for it out of habit and lose points. Where a stem names no method, the standard method is what is being asked for, and the two give different answers for the same dwelling.