LED Lighting Issue

U2cy2

Member
I have a clinic that has all LED lighting and we use Square D panels. One of the lighting circuits it pretty well loaded, 15A on a 20A breaker. This breaker get pretty warm to touch and I have taken infrared photos of the breaker. We have changed the breaker out and even moved its location but the condition follows. The breaker has never tripped out. The attached photo is showing a lower amp/heat reading than what I have seen but it is telling a story, just the same. There are other all LED luminaire circuits in this panel but they are not loaded as much as this circuit and are not getting hot.
I contacted Schneider Electrical for technical assistance on why the breaker is getting this hot within an air conditioned space (mid 70˚s f) and this is their reply:
“Hi Steven,
For the load in question, you may want to try the QO120HID type breaker as it has a different contact construction designed for high pressure sodium and metal halide type lighting circuits. Has the breaker tripped or is the concern the heating effect in the panel itself? The temperature rise limit of breakers under UL is 50C above ambient. So if your breakers are in a 25C environment, the limit would be 75C - you are at 46C.”
My question to you is with the circuit being all LED luminaires is the heat I am seeing coming from harmonics, due to all electronics load? Or would this be seen on the neutral only?
I have other clinics that have all LED luminaire circuits that are showing signs of heat compared to the other circuits within the panel (Square D as well) but not as hot as this circuit. To me this is a concern because it is above the “norm” and it is happening in a medical clinic, so it draws extra attention from me.
Have checked the screw (wire/breaker) connection and it meets the torque specs for this breaker.
What are your thoughts? I am more interested on why it is generating heat and how to prevent it from happening in the future than a fire hazard (at this point at least).
I, also, have asked the electrical engineers that designed the circuits what could be causing the heat but got the standard engineers answer when they don’t have a clue.
 

ptonsparky

Senior Member
I would call this a normal situation and the recommendation for the HID breaker is sound. The heat is coming from a normal load.
Take a VD reading across the breaker. Multiply that times the current draw and you will have wattage. I believe that times 3.4 gives you btu.
Compare with other breakers that are not causing concern. You will need a better than average meter to get your VD readings. A Fluke 87 or similar.

HD breakers made a huge difference in the past with HID lighting. Standard breakers would fail especially when used for switching.
 

kwired

Electron manager
Heat is produced when current flows, there is no perfect conductor with zero resistance.

Go to a place where there is a lot of circuits that are fairly loaded and every one of the breakers in a panel will be pretty warm, even almost hot to touch yet is within design of the breaker.

Go to average dwelling and you mostly only see this happen with breakers supplying HVAC loads or something that does run nearly constantly at a high load level. Most other high level dwelling loads don't have long enough run duration to cause significant heating of the breaker.

On top of that, breakers have thermally operated overload protection, they are designed to heat up to perform this function, the more load along with the more time the hotter they will be.
 

U2cy2

Member
Thank you for the advice, it
I would call this a normal situation and the recommendation for the HID breaker is sound. The heat is coming from a normal load.
Take a VD reading across the breaker. Multiply that times the current draw and you will have wattage. I believe that times 3.4 gives you btu.
Compare with other breakers that are not causing concern. You will need a better than average meter to get your VD readings. A Fluke 87 or similar.

HD breakers made a huge difference in the past with HID lighting. Standard breakers would fail especially when used for switching.
 

ramsy

Senior Member
..One of the lighting circuits it pretty well loaded, 15A on a 20A breaker. ..
Check that #12 non-linear neutral load with Amp clamp, to see if it exceeds16A.

Without adjusting the load x (1.25) for continuous-lighting loads, in violation of NEC 210.19(A)(1), nor counting nonlinear neutrals as current carrying conductors, in violation of NEC 310.15(B)(5)(c), knuckle heads often use "9 CCC's Rule of Thumb" to overheat wire in conduit.
 

ramsy

Senior Member
..the limit would be 75C - you are at 46C.”
Check the wire terminals, lugs, & terminations.

The limit is 60C, if the wire type is TW, or Romex, or fuse box / load center <= 100 Amps, and not otherwise listed & labeled for 75C.
 

synchro

Senior Member
When you're measuring current on LED lighting circuits make sure that you use a True RMS clamp meter. Some only give you an average of a rectified current waveform and apply a scale factor to display an equivalent RMS value, but this is only valid for a sine wave without harmonics. For nonlinear loads that have short peaks in the current waveform (typical in LED lighting), such an "averaging" meter will understate the actual RMS current. That might cause you to think you have sufficient margin on breakers and conductors when you don't.
 

kwired

Electron manager
When you're measuring current on LED lighting circuits make sure that you use a True RMS clamp meter. Some only give you an average of a rectified current waveform and apply a scale factor to display an equivalent RMS value, but this is only valid for a sine wave without harmonics. For nonlinear loads that have short peaks in the current waveform (typical in LED lighting), such an "averaging" meter will understate the actual RMS current. That might cause you to think you have sufficient margin on breakers and conductors when you don't.
But at same time actual current must be low enough the breaker doesn't trip.
 

hillbilly1

Senior Member
Not to sidetrack this post, but I had a ups load that was so bad, the neutral current was slightly higher than the two hots, and the hots were pretty much balanced. Harmonics are a b*$&!
 

kwired

Electron manager
Not to sidetrack this post, but I had a ups load that was so bad, the neutral current was slightly higher than the two hots, and the hots were pretty much balanced. Harmonics are a b*$&!
I'd guess when you are electronically creating the wave form from such types of sources the source itself probably adds to the issues because it isn't necessarily creating a sinusoidal wave to begin with then you add even more distortion from supplying non linear loads.
 
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