IR Thermometers?

About five years ago I performed a complete evaluation of every connection at panels and transformers at the Fairbanks Memorial Hospital in Fairbanks, Alaska using a handheld IR thermometer. It worked very well. The temperature of terminals appeared directly proportional to the amount of current they carried. I was following up on a IR photo evaluation performed by a major electrical contractor that found several hot spots but did not record the exact temperatures or repair them. My job was to fix the hot spots . I verified the hot spots, and in most cases found loose terminals. In one case I found an overloaded 20 ampere circuit breaker. It was carrying 21 amperes continuously and was running at higher than 75 degrees C. The thermometer was a Raytek built by Fluke that cost about $200, as I recall. Of course having a valid calibration by a lab before beginning the job was important.

Yes, I have one. Bought it to balance the radiators in a new central heating system, for which it is excellent. Next use was to go round the house finding thermal leaks, i.e cold spots inside or hot spots on the outside, and fix the thermal insulation. Useful for checking the temperature of fridge, freezer, oven, which it does instantly without waiting for any settling time. You can measure your body temperature (point it in your mouth, under your arm, etc). Pointing it out through an open window will give you the outside ground temperature. Pointing it up to a cloud gives you the air temperature at cloud height (-50C is typical in winter, even when well above freezing at ground level).

Actually, it's quite a nice toy all round. If you get bored with the temperature sensing part, you can play with the laser pointer, e.g. have the cat chasing the red dot around the floor. I would imagine it could be quite educational for children, but I would avoid one with a laser pointer in this case.

There's just one thing they are completely useless for, and that's measuring the temperature of bare copper, because it behaves like a mirror in the infra-red. You may recall that I originally bought it to measure flow and return radiator temperatures in a new central heating system, i.e. bare copper pipes;-) This is easily solved in this case by painting the pipe, sticking a bit of tape on it, or pointing the thermometer to the enamelled pipe stub on the radiator.

I also bought one for my dad who likes gadgets like this. He has used it when cooking, e.g. to check that a cassorole is reheated enough before serving (and found it wasn't the first time he used it for this).

I have used the Sears $50 unit for checking operational battery temperatures, works well for the price, none have failed in the field.

Today I bought a $6.99 unit on sale at Harbor Freight (requires coupon that was emailed). About the size of an automobile keyless fob, no laser spotter, and a wide angle. Need to hold it close to the item, but essentially the same reading as a Sears unit for room temperature objects.

Johnstone Supply has as a monthly special a $29 unit with laser, but I have not tried one. Bill Kaszeta Photovoltaic Resources Int'l Tempe Arizona USA snipped-for-privacy@pvri-removethis.biz

I use one for checking breaker and wiring temperatures, and it works well. The advantages of the higher end units are adjustable emmisivity, and a smaller target area at a given distance, meaning that you can get readings while remaining further away from the surface (a definite advantage when checking live panels). If you look at the specs on several, you will see the differences in that figure.

Ben Miller