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NCCER Exam Questions and Answers|
May/June 2025| Verified 100%
A plumber is installing a backflow preventer on a commercial building's water supply line. Why
is this installation necessary?
It keeps dirty water (like from toilets or sprinklers) from flowing back into the clean drinking
water. That’s super important for health and code compliance.
During a pressure test, the gauge drops slowly over an hour. What does that suggest?
There’s probably a small leak somewhere in the system. Even a slow pressure drop means air
or water is escaping, and it needs fixing before the system’s passed.
Why is it risky to use a pipe wrench on chrome-plated fixtures during installation?
Pipe wrenches can mess up the chrome finish and leave teeth marks. You'd usually use a
strap wrench instead to avoid scratching it up.
A pipefitter is working in a tight space and needs to join two copper pipes. What’s the best
joining method here?
Soldering (sweating) works well, especially if there's not enough room for press fittings or a
torch. Just prep the pipe ends properly and use flux.
, 2
If a drawing says the pipe slope is 1/4 inch per foot, what does that mean in simple terms?
For every foot the pipe goes horizontally, it should drop a quarter inch. That’s the right slope
for drainage so stuff flows out properly.
Why do plumbers avoid mixing copper and galvanized steel pipes directly?
If they touch, they can cause galvanic corrosion, where one metal eats away at the other. A
dielectric union helps stop that.
What’s the main danger of using PVC pipe in a hot water line?
PVC isn’t heat-resistant and can warp or burst if hot water runs through it. CPVC or PEX
would be safer for hot water.
A pressure-reducing valve (PRV) is acting up and the water pressure spikes. What’s likely
wrong?
The PRV might be stuck or broken. It’s supposed to bring high pressure down, so if it’s
failing, pressure in the system can get too high and cause damage.
You see greenish-blue stains on copper pipe joints. What’s going on there?
That’s usually from moisture and oxidation. It could mean a tiny leak or poor soldering that’s
letting water seep out over time.
NCCER Exam Questions and Answers|
May/June 2025| Verified 100%
A plumber is installing a backflow preventer on a commercial building's water supply line. Why
is this installation necessary?
It keeps dirty water (like from toilets or sprinklers) from flowing back into the clean drinking
water. That’s super important for health and code compliance.
During a pressure test, the gauge drops slowly over an hour. What does that suggest?
There’s probably a small leak somewhere in the system. Even a slow pressure drop means air
or water is escaping, and it needs fixing before the system’s passed.
Why is it risky to use a pipe wrench on chrome-plated fixtures during installation?
Pipe wrenches can mess up the chrome finish and leave teeth marks. You'd usually use a
strap wrench instead to avoid scratching it up.
A pipefitter is working in a tight space and needs to join two copper pipes. What’s the best
joining method here?
Soldering (sweating) works well, especially if there's not enough room for press fittings or a
torch. Just prep the pipe ends properly and use flux.
, 2
If a drawing says the pipe slope is 1/4 inch per foot, what does that mean in simple terms?
For every foot the pipe goes horizontally, it should drop a quarter inch. That’s the right slope
for drainage so stuff flows out properly.
Why do plumbers avoid mixing copper and galvanized steel pipes directly?
If they touch, they can cause galvanic corrosion, where one metal eats away at the other. A
dielectric union helps stop that.
What’s the main danger of using PVC pipe in a hot water line?
PVC isn’t heat-resistant and can warp or burst if hot water runs through it. CPVC or PEX
would be safer for hot water.
A pressure-reducing valve (PRV) is acting up and the water pressure spikes. What’s likely
wrong?
The PRV might be stuck or broken. It’s supposed to bring high pressure down, so if it’s
failing, pressure in the system can get too high and cause damage.
You see greenish-blue stains on copper pipe joints. What’s going on there?
That’s usually from moisture and oxidation. It could mean a tiny leak or poor soldering that’s
letting water seep out over time.
