Maryland grounding and bonding practice

Maryland runs the journeyperson exam through PSI Services: 70 questions in 3 hours 30 minutes, open book on the 2020 NEC, and 70% to pass. Article 250 shows up across that test more than almost any other single article, and it is where a lot of candidates leak points without realizing it.

Worked example: sizing the grounding electrode conductor

This is the kind of grounding question the Maryland exam loves, because it forces you to open the right table and read the correct row under time. Work it the way the exam wants, off Table 250.66.

The setup

A service is fed with 3/0 AWG copper service conductors. What size copper grounding electrode conductor does it need?

The steps

1. Find the size of the largest ungrounded service conductor. Here it is 3/0 AWG copper.
2. Open NEC Table 250.66 and read down the copper column. 3/0 copper falls in the “2/0 or 3/0 copper” row.
3. That row calls for a 4 AWG copper grounding electrode conductor. So the answer is 4 AWG copper.
4. Check the exception. Under 250.66(A), a grounding electrode conductor that runs only to a ground rod never needs to be larger than 6 AWG copper, no matter what the table says.

Notice what made that question slow if you did not know it cold: you had to know the answer lived in Table 250.66, read the right row, then remember the ground-rod cap is a separate rule in 250.66(A). That is two lookups and an exception for one answer. On exam day, the guy who knows the table number wins the point. The guy reading Article 250 front to back runs out of clock.

Why this topic costs points

Grounding and bonding punishes candidates for two reasons, and neither is trick questions.

• Article 250 is a maze of tables and exceptions. A single answer can route you through Table 250.66 for the electrode conductor, Table 250.122 for the equipment grounding conductor, and a bonding rule in 250.92 or 250.102. They look alike under stress. Reach for the wrong table and the answer is wrong even when your math is right.
• The open-book format rewards speed, not reading. Open book makes guys study less, then they cannot land on the right 250 table fast enough to finish 70 questions in 3 hours 30 minutes. The exam is testing whether you know where the rule lives, not whether you memorized it.

About one in four candidates passes the Maryland exam across both tiers. Grounding and bonding is one of the families that separates them, because it is high-volume on the test and slow to navigate if you have not drilled the flip path.

How to practice grounding and bonding for Maryland

The highest-value practice is not a giant trivia pile. It is confirming whether Article 250 is actually one of your weak families, then drilling the lookup until 250.66, 250.122, and the common bonding rules are automatic. We do not claim a fixed number of grounding questions, because the honest move is to let the diagnostic point you at your real gaps first.

• Run the free 15-minute diagnostic to see your projected score and whether grounding and bonding is dragging it.
• If it is, drill original 2020 NEC questions that walk the Article 250 flip path, so the right table comes up by reflex.
• Set up your codebook the legal Maryland way, with permanent tabs on Table 250.66 and Table 250.122, so you are not hunting for them under the clock.

Ready to see whether grounding and bonding is one of your weak spots? Take the free Maryland diagnostic.