Safety 4:4
CP 1–Cathodic Protection Technician Course Manual
© NACE International, 2000
12/01/04
• Confirm that the AC power is off by testing as breaker contacts can
fuse together thus making contact in the tripped position.
• Lock out and tag the rectifier breaker or AC disconnect after turning
OFF when installing an interrupter, changing taps, replacing
components, or installing and removing the rectifier. This is a good
habit to form and is required by code in many areas.
• There is no testing that is required behind the panel with the rectifier
energized with the exception of measuring the input AC supply
voltage. This AC voltage measurement is only to be completed by
persons properly trained and is only to be measured if the terminals
are readily accessible at the side of the rectifier. Remember that even
with the rectifier breaker OFF, AC line voltage still exists up to the
rectifier circuit breaker.
• Remember to turn OFF, lock out and tag the AC disconnect when
working on or removing rectifier components. No one else can then
inadvertently turn the AC on before it is safe.
Lock Out / Tag Out
A lock out / tag out (LOTO) is intended to ensure that the power can not be
turned on inadvertently while people are still working on the equipment. In
addition it instills a safe work habit. As an example seat belts in vehicles
were felt a nuisance at first but now one feels uneasy if it is not on when the
vehicle is in motion. The same applies to a LOTO where if it becomes a
habit to follow this procedure, you will feel uneasy if it is not in place
making you more aware of the hazard.
In many jurisdictions it is required by regulation. There are some common
rules that apply:
• The person that installs the LOTO must be the one to take it off
• If there is more than one person working on the equipment, then a
group scissor-type lock is to be installed with each person’s lock on
it (Figure 5.1).
• The tag identifies the person, contact information, date and the
equipment being locked out.
• The equipment is not to be re-energized until it has been inspected to
make certain it is safe and all locks have been removed by the owner
of the lock.
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