IR Pics of Natural Gas Furnace & 30 Amp Breaker

[Kenneth (Kip) R. McCullough, Jr.]

These IR pictures were taken today from a 19 year old gas furnace and 30 amp breaker (notice the temperature of the top of furnace and breaker). The house also had extensive termite damage, polybutylene plumbing, mold inside the garage, and required a new roof and HVAC system. Ouch!

[Darren Spencer]

what temperature is too hot for a 30 amp breaker?

[Brian A. MacNeish]

Originally Posted by dspencer1

what temperature is too hot for a 30 amp breaker?

From the Square D website:

"Square D circuit breakers can be applied in ambient temperatures within the
range of -10°C to 60°C (14°F to 140°F). This document provides guidelines
to follow when adjusting for ambient conditions."

So if it may be used in 140F ambient, it would be expected that it may operate at a higher temp but be derated above some chosen temp. What is hot to us may not be "hot" to a breaker that was designed to operate in hot conditions.

Check with the manufacturers instructions and limitations.

[Dan Bowers, CMI]

What Camera you using (model, etc).

[Kenneth (Kip) R. McCullough, Jr.]

Originally Posted by dbowers

What Camera you using (model, etc).

Hey Dan,

I have the Flir B Cam SD.Very long battery life.

[Darren Spencer]

exactly, the breaker can operate at 140 so what is the Ouch ? Seems everyone gets these cameras and reports anything that is red as a flagged area.

[Stephen W. Stanczyk]

Just because the breaker is manufactured to operate within the given temperature range doesn't mean there isn't a problem. Looking at the other breakers with a greatly different temperature range makes one wonder why this double pole breaker is running at such a different temperature.

My first thought was it was a split bus with this breaker feeding the lower section, but the conductors don't look large enough and don't take the path of the normal feeds. My second guess is either the water heater or an electric baseboard/wall heater. Both suck up the juice, especially when we first start testing.

So Kip...... what was the breaker operating?

[David A. Andersen]

1st; a gas furnace runs on 120vac.

You are showing a 240VAC. Wrong label?

2nd the furnace your showing may likely get that hot during operation.
I can't tell by any photo (IR is the worst), buy you appear to have a non-induced natural draft furnace with an air break inside the furnace where it is hot.

Do you have any other information for us?

[Kenneth (Kip) R. McCullough, Jr.]

Originally Posted by dspencer1

exactly, the breaker can operate at 140 so what is the Ouch ? Seems everyone gets these cameras and reports anything that is red as a flagged area.

The temperature differential between the breaker shown in the IR picture and the temperature of the other breakers was 60 degrees, which presents a potential fire hazard. I would consider a potential fire hazard as a red flag. The “ouch” comes from the price tag to repair the problems with the house as listed in my original post.

[Brian A. MacNeish]

Originally Posted by kmccullough

The temperature differential between the breaker shown in the IR picture and the temperature of the other breakers was 60 degrees, which presents a potential fire hazard. I would consider a potential fire hazard as a red flag. The “ouch” comes from the price tag to repair the problems with the house as listed in my original post.

Were all other breakers loaded to the same level/% as the "hot" one?
Did you use a clamp-on meter to obtain/compare amps?

Do we have a standard to guide us and any test /safe level #'s against which we can compare what we can find in the field.

Did you consult the breaker manufacturer's literature or contact them to see if they considered the temps a problem?

[Jim Seffrin]

Dear All:

The Standard for Infrared Inspection of Electrical Systems & Rotating Equipment provides detailed inspection procedures and reporting requirements as well as operating temperature limits for in-service electrical devices. It also provides an IEEE formula that allows one to calculate the maximum allowable temperature for any operating electrical component.

While it is possible for some untrained infrared imager operators to 'cry wolf' without any justification, I believe that is not the case here.

Referring to the thermal image and allowing that the measured temperatures are reasonably accurate, the body of the circuit breaker is at or above 140°F or 60°C. The line side connections of the breaker connections appear to be operating higher still.

According to the above-referenced Standard, the maximum allowable temperature for a molded case breaker is 60°C at 100% load. For breakers operating at lighter loads, this number would be lower. Although load readings were not provided, it is unlikely that the subject breaker was carrying 30 amps.

Were this my inspection, I would have reported this breaker as an exception. Based upon experience with similar items, I would expect that the observed thermal pattern was due to either:

• an internal defect such as a loose or deteriorated contact or
• a loose or deteriorated line side connection

Should you be interested in obtaining a copy of the Standard for Infrared Inspection of Electrical Systems & Rotating Equipment, copies are available from the Standards section of the Infraspection online store.

Please feel free to give me a call directly if you need further info.

[Mario A. Kyriacou, CHI]

Thanks Jim!

[Dale Duffy]

I have used my IR Thermometer on breakers and all of them were 140+ because it was 115 degrees outside where the service panel was located.

Breakers operating under a load were 160+ with no apparent problems in a new service panel positioned directly in our hot Arizona sun.

[Brian E. Kelly]

Originally Posted by dduffy

I have used my IR Thermometer on breakers and all of them were 140+ because it was 115 degrees outside where the service panel was located.

Breakers operating under a load were 160+ with no apparent problems in a new service panel positioned directly in our hot Arizona sun.

Yeppers Dale.

[kweiss]

Actually, I think you prove the point, Dale.

It is not as much about the temperature by itself as it is about one particular breaker being significantly hotter than the rest, given similar conditions and loads. I see pretty hot panels in garages in our summers too, AFCI in these can be 20 - 30 degree warmer when they group them.

I would have probably noted this breaker to, based on the limite dinformation here. If I see one breaker that much hotter than the other in the panel. (I used to use my IR thermometer too, before my camera.)