Lightbulb Testing - Entertainment or Enlightning
It is, without doubt, very entertaining. Everybody likes to see stuff “blown up”, so the unprotected testing of the incandescent bulb gets everybody’s attention. However, the test demonstration that is more important is the one where the same type of bulb is exposed to the same transient energy with the SPD connected and suffers no damage. It doesn’t have the same entertainment value, but it demonstrates the desired result, an operating light bulb.
Enter the compact fluorescent bulb. This is the type of bulb that is being mandated for future use by all Americans. It is much more energy efficient than the incandescent bulb, consuming as little as 20% of the energy required by an incandescent bulb, with the same light output. Its life expectancy is as much as seven times greater than that of the incandescent bulb. The question is, “is it more resistant to transient voltage surges?” The results of this test demonstrate that the answer is “no”.
The transient energy that is applied to the bulbs in this test, while not of the magnitude of lightning, is a fairly high level of energy (6,000 volts/3,000 amps). It is a very brief impulse (20 micro seconds). It is the same test that SPDs are exposed to by UL for their VPR ratings. The SPD is required by UL to survive this level of exposure and continue to operate without failure or significant degradation. The light bulb isn’t. Fortunately for us all, these are not everyday levels of transient exposure. The everyday levels are the ones that chip away at the bulb and are the primary cause of premature failures. These transients are commonly found in building circuits at a level as low as 2,000 volts and 67 amps. They are oscillatory in nature, at a frequency in the 100 kHz range. Reducing the occurrence of these type transients will increase the life expectancy of not only the lighting in the facility, but all electrical and electronic equipment present.
As surge suppression professionals, we have known for many years that fluorescent lighting is particularly susceptible to damaging transients. The ballasts themselves are a well-known source of those transients. Compact fluorescent bulbs are no less affected, and may actually be more susceptible to those transients. The effect then is reduced bulb life, resulting in frequent failures. The bottom line is that the cost of these energy efficient bulbs, left with no surge protection, may actually be greater than that of their incandescent counterparts. Incidentally, we subjected a new LED bulb to the same test and the results were the same.