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The Most Common Cause of Secondary Ground Faults 
What is a Secondary Ground Fault? 
In 1999, changes were made to UL48 to include UL2161. To simplify, UL2161 states that all transformers must have a Secondary Ground Fault Interrupter (SGFI) that will shut the secondary power (the power to the neon) off when the SGFI detects that the secondary power has shorted 15mA of current or more to ground. The result of these changes is that we now have technologically advanced neon transformers that reduce fire risks, however, we now have to take on the new challenges in understanding what causes ground faults in the first place. 
The problems inherited with the changes brought on by UL2161 are a result of the fact that UL2161 did not apply any changes to any other component of the total neon system, particularly the GTO wire.  In other words, the transformers changed, but nothing else did. Many of the GTO wire brands that you've grown accustom to using prior to 1999, simply will not work well with SGFI transformers; regardless of the transformer manufacturer, a problem will present itself. 
The Most Common Cause: 
Everyday, a service person gets tired of scratching his head while troubleshooting a ground fault issue and replaces a good transformer. Sometimes, this may correct the problem temporarily and while the sign is operating normally, the actual problem still persists. The service person will be back to this sign again in the near future. The main problem lies within something that is out of plain view. It's not something that you can always look at and determine the cause. Nearly every single time that there is a secondary ground fault detected by the transformer, the problem is the GTO wire that was used. Even the most popular brand of  integral sleeve GTO wire will create these problems because it contains a PVC coating. Now, there's no need to go ripping out every piece of GTO wire in that sign. The problem can usually be isolated to the first leads coming from the transfomer's secondary terminals. These are the wires that carry the highest voltage and the most current. This is important for two reasons. Several factors contribute to the demise of the PVC wire. The high-voltage creates radiation emitted from the wire's corona. This radiation breaks down the plasticizers that give PVC it's flexibility resulting in open cells in the already porous material. Further breakdown of the plasticizers in PVC wire are due to the presence of ozone and moisture condensation in the conduit. This combination produces an acid that overtime deteriorates the PVC coated wire. Remember, that this wire is in grounded metallic conduit and in a grounded sign. The open cells in the PVC allow the current to find it's way to grounded metal resulting in a transformer that has performed as required by UL. It has tripped off.  
The Only Solution: 
Since Transco is a leading manufacturer of neon transformers, it only made since for Transco to produce and distribute a GTO wire that would not deteriorate and adversely affect the total neon system. Silicone is the only solution. 100% silicone integral sleeve GTO wire from Transco does not contain plasticizers and therefore, is virtually unaffected by any of the environmental conditions that deteriorate PVC. The physical properties of silicone allow for greater insulation and flexibility in a wire that can last the life of a neon sign. Available in black and white, Transco's Integral Sleeve GTO wire is available at your local sign supply distributor. When you're tired of troubleshooting ground fault issues, switch to Transco's 100% silicone Integral Sleeve GTO wire! 
 
Transco, Inc. 
1059 Colite Drive 
West Columbia, SC 29170 
Ph: 800-869-6366     Fax: 803-794-8528 
transco@transco-usa.com