The Benefits of Fault Protection, Part 2

This is a continuation of last month’s discussion of secondary ground-fault protection, in which Johnson examined the industry’s initial experiences with SCGFP and assessed the code’s impact.

The fundamentals of harmonious ground-fault practices center on grounding. If functional service ground is present, everyone’s happy. Prior to the SCGFP requirement, transformers would hum right along without a service ground, albeit under unsafe conditions. Now, they will trip.

With SCGFP circuitry, a proper earth ground must be supplied with the primary. Accept nothing but a wire for this ground path. Using conduit for bond/ground is not acceptable. If you are mounting channel letters at a distance from the power service, include longer primary tie-ins in preparation for an electrician’s hook-up.

Frustration peaks during SCGFP-transformer installation when proper ground isn’t supplied or is insecure. Without firm bonding connections and proper materials, there’s no peace of mind. Ground verification is the first step in the SCGFP troubleshooting process.

The same care must be taken to verify polarity. SCGFP circuitry is polarity-sensitive. Make sure that neutrals are indeed neutral and hots, hot. Use a multimeter to confirm that the black wires are hot and the whites are neutral in all lengths extending back from the transformers to the panel. While inspecting wiring, verify that primary supply wires aren’t commingled with secondary wires. Inadvertent bundling of these wires may also cause trips.

Site surveys assume more importance. If an installation crew encounters the unexpected, penalties paid in lost time or multiple visits will escalate. Double-check the intended location of transformers, secondary wiring, tube clearances, etc. Make sure that, if someone else provided the primary power service, it’s what you need.

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Troubleshooting with SCGFP

The "new reality" for modern neon work assumes that "old-style" traditional troubleshooting techniques won’t be the most time-effective on service calls. Pre-SCGFP, the first step might have been to obtain a spark off the transformer. Today’s experience dictates that, even if that comforting spark can be achieved, there’s little indication of the fault’s source. If the source isn’t remedied, the neon remains unlit.

Before SCGFP, a serviceman could expect to see an arc, hear a buzz or smell the ozone. Fault-protected transformers more typically shut off before conditions worsen. So, other techniques must be used to complete the job expeditiously.

Some SCGFP transformers feature a half-hour "bypass" mode. As allowed by UL, when in bypass mode, the transformer disregards SCGFP. This assumes the source of faults can be located and cleared.

Often, it’s not that simple. In many cases, multiple circumstances combine to trip the device. Individual problems may not trip the transformer, but they may in combination. The challenge becomes how to identify and fix the worst problems. A bypass function may help, but there’s a better option.

A true RMS multimeter and high-volt probe are essential for today’s neon service work. They enable servicepeople to leave a job site quickly in a single visit. The first troubleshooting step should be to verify the acceptability of the primary power supply. Use the multimeter to verify that the input voltage is within 5% of expectations. It can also be used to check such features as polarity and neutral voltage.

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The multimeter and HV probe can identify other factors: transformer output, the consistency and efficiency of tubes and loading. As symptoms of a problem, undesirable readings prompt component and functionality tests.

Implementating these trouble-shooting procedures makes the service call much easier. The cost of a good meter and probe adds up to less than $500, an investment that may pay for itself on one service call.

One caution: Even after implementing these procedures, some sources of faults, typically related to capacitive effects, can’t be clearly identified. Minimize capacitive effects by following guidelines for such factors as spacing, transformer selection and GTO/conduit use. Although field-testing and measuring capacitance is difficult, you can minimize the conditions that make it probable.

Troubleshooting remedial work is akin to playing Sherlock Holmes. By eliminating the impossible, the solution remains. So, rule out the most obvious circumstances first, and verify as many ideal circumstances as possible.

Further thoughts

Implementation of the ground-fault mandate temporarily turned the neon world upside down. Changes continue, but we’re approaching stability.

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As we appear to be leaving the "looking-glass" world, bright spots appear. SCGFP will certainly help raise standards of workmanship, which benefits quality-conscious sign companies. SCGFP provides a major disincentive to corner-cutting practices. Additionally, fault protection enforces a stricter discipline on sign installers, thereby reducing problems in the field.

Hopefully, fewer problems mean happier customers. From a long-term perspective, SCGFP may benefit the neon trade’s vitality. Sign maintenance costs should decrease. After all, the very problems proscribed by SCGFP also cause transformer failures, GTO burnouts, etc.

Granted, "selling" safety is difficult, especially when new products imply that prior art was unsafe. However, it can be done with discretion and creativity. Long-term performance sells credibility. Use of SCGFP will definitely improve long-term operating costs of neon signs. It may even make sign leasing a more attractive alternative for clients and sign companies. The opportunities presented by this new technology far outweigh transitional implementation costs.