It is no secret that sub-par electrical contractors often arrive at a low bid price by underestimating hours and eliminating quality control where it should be required. Many owners considering bids are aware that contractors may be taking shortcuts, but as the saying goes, they don’t know what they don’t know and may not be aware of what to look for and the questions they should be asking. One area where clients should pay close attention is in the quality control of low-voltage systems, specifically wire and cable testing.
For many years, electrical specifications require testing of medium- and high-voltage feeders, including but not limited to 4160V, 13200V and higher, through hipot testing. Panel sub-feeders with supply power to distribution panels and power and lighting panels must be megger tested as well. If a cable does not pass the test, or if the insulation is compromised, spec requirements state that the cable must be replaced and retested. These specifications, however, are often lacking when it comes to low-voltage systems.
Low-voltage systems and microelectronics have grown tremendously over the past decade or so through lighting controls, advanced security systems, shade controls, building automation and wireless antenna systems for Wi-Fi and mobile phones, etc. This has increased use of Cat6 and Cat6a cable, twisted shielded and unshielded cable, and coaxial cable, as well as custom vendor-prefabricated cable. Low-voltage testing, however, has lagged behind the high-tech demand of today’s technology and, unlike medium- and high-voltage, is not mandatory, so many low-voltage contractors still opt skip this important step to save time and money. As a result, problems such as intermittent connections, shorts, opens and grounds, impedance, and even induction are frequently found during startup and commissioning, and often require an inordinate amount of time to diagnose. Specifications rarely go into great detail on low-voltage systems testing, and these problems illustrate precisely why they should be required on every project.
Though low-voltage quality control is slowly beginning to catch up with today’s market, it is highly recommended that low-voltage installation contractors adopt comprehensive wire and cable testing programs, and clients should be aware to ask for it on their projects. It is true that such testing takes more time, but it can prevent the vast majority of common problems that can arise and result in unnecessary delays, back charges, finger-pointing, hard feelings, and an unhappy customer.
Omni Instrumentation & Electrical Services, Inc. is a premier instrumentation and electrical contractor, providing superior total care solutions since 1986. Services include instrument installation, tubing installation, instrument calibration, control loop testing, startup and commissioning, power and lighting, process control wiring, BMS wiring, telecommunications and data wiring, fire alarm wiring, security wiring, process network wiring, and control panel fabrication. Omni Instrumentation & Electrical Services, Inc., is certified in Foundation Fieldbus, Profibus, DeviceNet and ASI-Bus installation.