While the 1st version of the ground fault circuit interrupter (GFCI) was developed in the early ‘60s, it was in the 70’s they became more prevalent in the form of circuit breaker types. Quite unreliable due to false readings and nuisance “tripping of the circuits”, they were highly improved in the early 80’s when they began to emerge in the form of outlet receptacles.


The National Electrical Code (NEC) started making recommendations in the late ‘60s for some form of GFCI protection, increasing their recommendation and eventually making them code that the outlets or some form of protection be added to any area where a 120-volt receptacles might be in close contact with water, such as bathrooms, outside receptacles, garages, etc.

The true purpose of the GFCI is to “sense” when there is a current leakage between a power source and a grounded surface. The GFCI is designed to determine that there is a difference in the amount of electricity making its way into the circuit, versus some that might be “flowing out”. In this situation, a small amount of current, as little as 4 or 5 milliamps, is det

ected by the “sensing coil” built into the GFCI device, and the unit “shuts” off the circuit, stopping the flow. This reaction occurs less than one-tenth a second.

The product that “senses” this leakage, is simply called a “sensing coil”. Typically made up of a high nickel ring core, in a case shaped like a donut that can be as small as a dime in diameter, wound with copper magnet wire, then sealed in a potted case, it is the critical part of a GFCI. And it is a product that you want to buy from a reliable source!

Galaxy Transformer & Magnetics LLC has been providing sensing coils to the market for close to 10 years, and is produced at 1 of its 4 locations in China. 

While offering competitive pricing, quality is our #1 priority! With a total of close to 150 toroidal winding machines in China, there are few, if any other companies that have this type of capacity.  

Today, just about every house, old and new, aside from having GFCI’s throughout their house, will also have numerous household items with GFCIs built into their daily household products. Hairdryers, electric grills, electric cars, power tools are just a few to mention.

So, if you want to avoid those “nuisance-tripping’s”, and with competitive pricing, make sure your company specs Galaxy Transformer for your quality GFCI product