How is a transformer installed?
Installing a transformer is six steps: make safe, seat the unit, join the primary, join the secondary, test and record, and close up. The connections and lead entries are where most early failures begin.
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Step through the installation. Select a step below, or use Next, to see what is done and what to check.
Installing a transformer means making a series isolation transformer part of the loop and part of the fitting’s supply: make the circuit safe, seat the unit in the pit or base can, join the primary to the series cable and the secondary to the fitting, then test and record before closing up.
Most early failures start at the connections and lead entries. A poor or open primary connection can take out the whole series circuit, and strained or unsealed entries let moisture reach the windings. Support the body rather than the leads, use the specified connectors, keep the pit dry and drained, and check the rating suits the fitting. Treat every lead as live until the circuit has been isolated and proved dead under site procedures, and follow the design drawings and the manufacturer’s instructions at each step. Never energise a series transformer with its secondary open: an open secondary can develop a dangerous voltage, so make the secondary connection before the circuit is restored.
Frequently Asked Questions
Q1What are the main steps in installing a series isolation transformer?
Make the circuit safe and isolate it, seat the transformer in the pit or base can, make the primary connection to the series cable, make the secondary connection to the fitting, test and record the unit, then close up the pit. Always follow the design drawings, the manufacturer’s instructions and site procedures.
Q2Why must the circuit be isolated before installing a transformer?
The transformer’s primary is in the series loop, which can carry a high voltage and a constant current. An open primary lead on an energised circuit is dangerous. The circuit must be isolated and made safe under site procedures, and treated as live until proven otherwise.
Q3Why should the transformer not hang from its leads?
The leads and their entries into the housing are the weakest part of the seal. Hanging the unit by them, or leaving them tight or sharply bent, strains the entries and can let moisture in over time. Seat the body properly and leave the leads with slack, as the manufacturer specifies.
Q4Why is the connection the critical part of the installation?
In a series circuit a poor or open connection can take the whole loop out, not just one light. The primary and secondary connections must be the correct type, made and sealed as specified, and checked before the pit is closed.
Q5What should be recorded after installation?
The transformer’s position in the circuit, its rating and serial details from the nameplate, the test results, the date and who did the work. This links the unit to its history for maintenance, fault finding and later replacement.
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