Does heat affect Breakers?

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Forum topic by Victor708 posted 07-17-2011 02:20 PM 23805 views 0 times favorited 18 replies Add to Favorites Watch
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44 posts in 4533 days

07-17-2011 02:20 PM

Topic tags/keywords: question circut breaker harbor freight dust collector electrical

Hey guys, this may seem strange but everyday when the outside temperatures hit ~100 (daily here in Texas) my Hf dust collector starts tripping the breaker. At first I thought it was a bad breaker but a new one didn’t fix the problem. My breaker box is on the back of my house and is exposed to the sum for most of the day. I was able to get a little more working time by lifting the cover on the breaker a little letting the air circulate a bit. In the evening when the temps drop the problem goes away. I haven’t had this problem in the past because until I air conditioned my garage shop a couple of weeks ago, it would get too hot to work in there long before it hit 100 outside. Has anyone else experienced this or am I crazy and have different issue?



-- "If a man is alone in the forrest with no woman to hear him. Is he still Wrong?"

18 replies so far

View Gregn's profile


1642 posts in 4203 days

#1 posted 07-17-2011 02:36 PM

I live in Oklahoma, so I have the similar weather situation here with the 100 degree temps. You have a different issue going on. Have you tried the DC on a different circuit? If its just the DC that has the problem I would check that if its still tripping breakers.

-- I don't make mistakes, I have great learning lessons, Greg

View bent's profile


311 posts in 4888 days

#2 posted 07-17-2011 03:07 PM

your circuit breakers contain a bimetallic strip that flexs with temperature change. current through the breaker creates heat which flexs the strip and causes the electrical connection to open. you’re not crazy, the high ambient temperature could be causing the breaker to trip without an excessive current.

View cutmantom's profile


408 posts in 4254 days

#3 posted 07-17-2011 03:26 PM

is the circuit able to handle the DC, a 15 amp breaker running a 15 amp tool is pushing the limit, the high temp outside may be all that is needed to push it over the limit, also is there something else on the same circuit

View superstretch's profile


1532 posts in 3912 days

#4 posted 07-18-2011 07:15 AM

The DC is in the air conditioned shop? If not, the heat could be causing it to run inefficiently, creating a high draw.

Also, you say the breaker is in the sun most of the day—Consider this: My grill was out today and the temp was ~90. Unfortunately, I leaned up against the grill and burned my arm (I hadn’t fired it up yet). The reason? The thermometer on the lid said 160. Your electronics are cooking inside a metal breaker box..

-- Dan, Rochester, NY

View David Grimes's profile

David Grimes

2080 posts in 3859 days

#5 posted 07-18-2011 07:35 AM

@ superstretch makes a great point. I have a 200 amp meter base / services disconnect that gets beat by the afternoon sun. Knowing that, I originally bought a white one. It is much cooler than the smaller medium gray colored ones for the heat and a/c units and the pool pump, etc. Painting your box would no doubt lower the heat gain of the box itself.

I have always heard that the Square D industrial breakers (QO, I believe… not the Homeline) have more heat resistant bakelite and the breaker itself due to the harsh industrial environments they are placed into. Again, Mr. Anal here spent twice as much for the QO’s in my main house breaker box (including GFCI breakers, about a dozen piggy backs, and now a handful of arc faults).

My outside stuff (again for heatpumps and pool) is GE, Murray, and Square D Homeline.

-- If you're going to stir the pot, think BIG spoon or SMALL boat paddle. David Grimes, Georgia

View Victor708's profile


44 posts in 4533 days

#6 posted 07-18-2011 02:24 PM

Thanks for all the responses guys. Just a few particulars to answer some of the questions brought up. The dc is rated at 14 amps and was on a shared 15 amp circut. I know it was pushing the limits because I would loose have of my shop flourescents when I kicked it on. Once I started having problems I moved it to a dedicated line but the problem presisted. The dc is inside the a/c’d shop so the motor running under abnormally hot conditions is not an issue. With all the comments here I’ve come to the conclusion my problem is heat related. I think it may be time to consider the cost of having a 100 amp sub panel installed. Besides, I have four pieces of equipment including the a/c running on 220v. I’m growing tired of having to swap plugs to use some of them.


-- "If a man is alone in the forrest with no woman to hear him. Is he still Wrong?"

View Grandpa's profile


3264 posts in 3895 days

#7 posted 07-19-2011 12:20 AM

Heat is the enemy. heat also makes the breakers work. You are crowding the breaker anyway. You have a 14 amp motor running on a 15 amp breaker. You need to rewire and have a 20 amp breaker. Don’t just change the breaker unless you have 12 ga wire. Don’t make that mistake. Hgh temps cause more resistance so it is a vicious circle.

View peteg's profile


4438 posts in 4042 days

#8 posted 07-19-2011 12:41 AM

The Bi metalic activated breakers build up a memory to continual tripping resulting in say a 14a unit eventually tripping well below its nominated rating, I would suggest you are trying to protect your motor with a breaker running “on the redline”. protecting an inductive motor load with high start current is a different requirement to a basically resistive say heating/lighting load. Not sure about your set up but we used to used “motor rated” breakers when I was in the game many years ago, these are built specifically to withstand start up inductive loads, if you give your supplier the name plate ratings he will be able to supply you with the correct devise.
Hope this helps you. :)

-- Pete G: If you always do what you always did you'll always get what you always got

View fussy's profile


980 posts in 4270 days

#9 posted 07-19-2011 02:34 AM

You answered your own question by opening the box cover to allow better air circulation. Try to vent it in some way, or shade the outside wall on which it’s mounted. Or move to Nome, Alaska.

-- Steve in KY. 44 years so far with my lovely bride. Think I'll keep her.

View davidwilson's profile


1 post in 1019 days

#10 posted 12-13-2018 02:24 AM

I have always heard that the Square D industrial breakers (QO, I believeā€¦ not the Homeline) have more heat resistant bakelite and the breaker itself due to the harsh industrial environments they are placed into.

View WoodenDreams's profile


1412 posts in 1130 days

#11 posted 12-13-2018 06:59 AM

Try building a awning over the box, to keep it in the shade and away from the elements of weather. Usually high draw causes the breakers to flip if it on the right breaker. And which HF dust collectors do you have. What does the manual say on reguired wiring.

View therealSteveN's profile


8670 posts in 1793 days

#12 posted 12-13-2018 12:53 PM

I think it may be time to consider the cost of having a 100 amp sub panel installed. Besides, I have four pieces of equipment including the a/c running on 220v. I m growing tired of having to swap plugs to use some of them.


- Victor708

Not sure where you are on accumulating tools, and or considering swapping some 110 for 220. When I initially did the electric to my newer shop I put in a 100 Amp service thinking I would never come close to filling it. Electrician just put in a separate 60 amp box last week. Plan for more than you need, and you’ll never need more spaces in a box. That doesn’t come close to covering the potential for needing more wire run though. I’ve been told several times over the last month, if I’d just put in a 200 amp box, I’d have had enough spaces from the start. Just saying, think about it before choosing.

I would also give the nod to what davidwilson just said. All boxes, and the breakers for them are NOT created equally. Asking local building inspectors you can ask a generic question that won’t put them on the spot. What brand of boxes, and breakers do you see used most often? Likely it will be Square D, QO line. Looking at prices you will also likely find they are NOT the dirt cheapest price available. So electricians are spending more money to put them in. I’d call that an important thing to know.

Plus I would suggest to only use a 20 amp line or better for power equipment. I would only suggest a shared 15 amp for electric lights.

-- Think safe, be safe

View ibewjon's profile


2610 posts in 4012 days

#13 posted 08-08-2020 09:48 PM

I have been at this over 40 years, and Square D QO is the ONLY breaker I would use. Period. Yes, the sun shining on your panel is heating the breaker which was basically overloaded anyway. Opening any panel and leaving the cover partially off is dangerous. Get a panel in the shop, and run a properly sized, dedicated circut to the DC and other large machines. As with anything, you get what you pay for in breakers. Some cheap things are ok, but breakers and properly sized circuits are a safety issue. That is why so many home fires are electrical. I see so many spend big $ on a machine, then cheap out on the electrical to power it.

View Knockonit's profile


949 posts in 1421 days

#14 posted 08-09-2020 01:43 AM

lol, my 400 amp panel is in sun from about noon till about 7 every day, and today it was 114, so have never had issue with panels, or breaker getting hot from sun, now a short or bad connection or bad ground, not that either but generally they will create heat ect.
breakers go south, some may not even appear to be popped, can say have had a few of those over the years.
best of luck with fix, sometimes its just prudent to hire an electrician to review issue. just to be safe, versus a fire or hazard situation
Rj in Arizona

-- Living the dream

View ibewjon's profile


2610 posts in 4012 days

#15 posted 08-09-2020 07:28 PM

Your circuits are not loaded to the maximum. That is a good thing, and why you have no problems. In the NEC there are calculations for when the motor is in one environment and the breakers and starters are at a different temperature. Heat does have an effect.

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