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I am an electrician at a hospital in the maintenance deptmartment. We are in the process of updating some of PM procedures that reflect the NFPA 70E requirements for safety, what does and does not need to be done. The current PM, that was in place before I started, requires to remove panel covers every three years and take images of the connections. We recently had a Fluke demo/training and he mentioned that if the electrical load we are scanning is not at 40% amp load of the circuit , there is no need to to do the scan because it would not show any thing. That is the second place I have heard of the 40% load being a minunum load. Because we are a hospital, most of our distributions are set up to be tied together in case of a failure upstream. So by design most of our distributions are at less than 40%.

Is the 40% rule accurate? It would save alot of work if we did not to suit up and scan panels if they are at 20-30% of rated capacity.
 

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I am an electrician at a hospital in the maintenance deptmartment. We are in the process of updating some of PM procedures that reflect the NFPA 70E requirements for safety, what does and does not need to be done. The current PM, that was in place before I started, requires to remove panel covers every three years and take images of the connections. We recently had a Fluke demo/training and he mentioned that if the electrical load we are scanning is not at 40% amp load of the circuit , there is no need to to do the scan because it would not show any thing. That is the second place I have heard of the 40% load being a minunum load. Because we are a hospital, most of our distributions are set up to be tied together in case of a failure upstream. So by design most of our distributions are at less than 40%.

Is the 40% rule accurate? It would save alot of work if we did not to suit up and scan panels if they are at 20-30% of rated capacity.
I never heard that, but maybe someone will chime in..
 

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While it is true you want max loading possible for IR scanning there is no "rule" that I am aware of.

However, it has been many years since I was a certified IR tech so things may have changed.
 

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Since I thought I might be forgetting something, looked through my FLIR textbooks from the level one course I took sometime back, and I can find no metion of load requirements. It does stand to reason that a suspect connection would show up better under a heavy load. Since you can't shoot the connection screw (emissivity way to low on shiny stuff), a heavy load would radiate heat outward better to where the higher emissivity material is located (phenolic, insulation, etc...). But a good camera, set up correctly, should still easily spot a potential problem with lighter loads. No load, however, could be problematic.

Maybe the Flukes don't have the same resolution as the FLIR (I used a T-360).
 

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I talked to my IR Techs Level III and Level II Certified Thermographers,

And they said while 40% load is the optimum, loose is loose and heat is heat, and lose connections result in heat. If you see a thermal condition and measure the current, based on the type of connection, conductor size, temperature and current you can calculate if the connection has an issue. I had a picture of a loose neutral #12 AWG, carrying 2 or 3 amps and it was visually IR hot enough to draw attention of the Thermographer.
 

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We found issues in some panels where then load was 25-30%. Loose connection still caused heat as you would expect and the camera caught it for us.
 

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I am an electrician at a hospital in the maintenance deptmartment. We are in the process of updating some of PM procedures that reflect the NFPA 70E requirements for safety, what does and does not need to be done. The current PM, that was in place before I started, requires to remove panel covers every three years and take images of the connections. We recently had a Fluke demo/training and he mentioned that if the electrical load we are scanning is not at 40% amp load of the circuit , there is no need to to do the scan because it would not show any thing. That is the second place I have heard of the 40% load being a minunum load. Because we are a hospital, most of our distributions are set up to be tied together in case of a failure upstream. So by design most of our distributions are at less than 40%.

Is the 40% rule accurate? It would save alot of work if we did not to suit up and scan panels if they are at 20-30% of rated capacity.
If a connection is loose, say, at a breaker screw, an IR shot will pick it up at a lot lower percentage of load. It is worth the PM and after all, it is just labor...and money.
 
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