Light Bulbs Burning Out Frequently?  Put on your detective hat!  Part 2

In Part 1 we looked at some reasons why light bulbs can burn out prematurely. Now we will look at one of the situations we ran into with one of our customers.

In this situation the customer had a home office in their basement that utilized track lights as their main source of lighting. The light bulbs they were using were PAR 20 halogen which due to their hot operating temperatures tend to burn out more frequently than incandescent, CFL and LED bulbs. The customer was spending more than a hundred dollars per year replacing bulbs in the track light heads. He told us that sometimes they would replace a bulb and it would burn out the next day. So, what did I do to solve the problem?

Even though halogen bulbs tend to burn out more frequently what he was experiencing was not normal. Like any good detective the first thing I did was ask a few questions? Was this occurring in other parts of the house with other light fixtures? No. Where was he buying the bulbs and what was the brand? He was buying the bulbs at Costco and using reputable brands like General Electric bulbs. The house was not that old so I asked if this had been happening since he moved in? Yes. Was he screwing the light bulbs too tight? How tight is too tight he asked. Good question. Do they have kids or a big dog? Why are you asking me this? Was there anything else I should know? Whenever the heat pump kicked in the lights would dim.

So, not sure if happening all over the house, using good brand of bulbs and has been happening ever since the light fixtures were installed (which were the first fixtures because the house was new) and the heat pump was dimming the lights. Not sure if he is screwing in light bulbs too tightly. Where to start?

The first thing I did was check the house voltage. I measured around 124V which is not out of the ordinary. 120V is desired voltage but plus minus 1 – 2 % is not a problem. Second, I put an amp meter on the heat pump circuit to see if there was an unusual current spike when the heat pump engaged. I also wanted to see the “light dimming” effect it had on the lights. The heat pump seemed like a good suspect for the problem because if it was dimming the lights perhaps over time it affected the bulbs. Furthermore, because halogen tend to burn out more often maybe the heat pump was only affecting these bulbs and not the rest of the bulbs in the house. After doing the testing on the current and seeing the actual dimming effect nothing was out of the ordinary. The current spike when the heat pump started was not unusual and the actual dimming effect was almost imperceptible (heat pumps can cause voltage drops which can dim lights).

The last thing I did was check the fixtures to see if the light bulbs were being screwed in too tight. If you do screw them in too tight it compresses or squeezes the small tab in the bottom of the socket so that when you change the bulb again it does not make a good contact with the new bulb. This can cause electrical arcing which creates a lot of heat and can burn out a bulb prematurely. You can usually tell this is occurring as there will be some black residue on that little tab in the base of the socket and on the bottom of the bulb itself. It is hard to explain how tight is “too tight” but when you screw in a bulb it should be “snug” or just enough to make a good contact and actually light up.

After investigating my customers track lights I did not think there was a problem with the bulbs being too tight. To be certain after checking each fixture I pulled the tab in the bottom of the socket upwards with a pair of needle nose pliers (make sure the switch is off if you do this). This tab is made of malleable metal so it will bend. I was actually hoping this was the problem and told the customer to see if the problem continues and left for the day having run out of other ideas.

He called me back a few days later and told me another bulb had burnt out. Arrghh! Needless to say I was a little frustrated. I investigated most of the usual culprits of this type of problem but none seemed to be the cause. I wasn’t sure what to do next but I scheduled a time to go over again and hopefully get some inspiration while there.

In many crimes the criminal often makes a critical mistake which leads to their capture and arrest. Luckily, when I went back to my customer one of the light bulbs made a critical error.

Upon arriving I asked the customer for a new light bulb so I could change the light that had been burned out. I unscrewed the burnt bulb and screwed in the new one. One thing I noticed was that the bulb was fairly tight in the track light head. The track head in my customer’s fixture has a metal frame which makes contact with the top of the light bulb (or the glass part of the bulb). It did seem a little tight but I did not think too much about this. I put the track head back in the track and the bulb worked. Not five minutes later I heard a loud“poof” and the bulb I had just changed had burnt out. My customer actually told me that sometimes bulbs burnt out very quickly after being changed.

This was the “smoking gun” I needed to solve this problem (or crime if you want melodrama). My theory was that because the the track head was holding these par 20 halogen bulbs too tightly the bulb somehow this was causing the bulbs to burn out more frequently. Perhaps the difference in temperature of the bulb and the track head frame caused the glass of the bulb to crack (kind of like putting a cold glass in hot water). I am not totally sure what the reason is however, by changing the type of bulb from a par 20 halogen to par 20 LED bulb I have not heard from this customer in months. The LED bulbs do not get nearly as hot as a halogen bulb so I believe that the halogen bulbs which get extremely hot, combined with the design of the track light head which had a metal frame that made contact with the bulb too tightly, was the root of the problem.

So should everybody run out and buy LED bulbs to solve the problem of light bulbs burning out too frequently? Not necessarily, all though you will save on electricity costs. What it is important to remember is light bulbs burning out too quickly could be for many reasons and you need to go through a step by step process to find the culprit.

The actual cause of this type of problem is not always so simple as we saw in the scenario with the halogen bulbs. In Part 3 we will look at another situation that was not as hard to figure out but also was for a reason that you won’t find by googling it.