This was from this morning inspection typically what I find concerning temps between the two legs same amps on both legs the temp should be the same and as indicated with IR there is a temp differential.
This breaker was real special the cook top and the oven were remote from each other opposite sides of the kitchen. but the breaker was just a 30 amp and was double tapped with both appliances:( I shot the image right before the breaker tripped I suppose the breaker would be fine as long as one did not operate more than 2 cook top elements while the oven was in use;-)
Is there something wrong with this picture that one would think it was a danger? THW conductors are fine with a temperature of 167 degrees F and these are only at 113.9 degrees F and the breaker tripped due to overload.
I did not use the word danger I implyed the temp was unbalanced between the two legs with the same amp on both legs a reasonable person would assume that both legs would have the same temp, a loose connection that will just increase over time. I find loose connections before they burn off:D nothing wrong with a little preventive maint. As a matter of fact I recommend to clients to have all their breakers checked perodically for loose connections
I will add that the electrician might come out and find absolutely nothing wrong and comment as such. However, he would be mistaken. Most of them are unaware that a very common failure mode of both breakers and contactors is internal contact fatigue or wear. It is more common in circuits that operate either at their current ratings or are loaded above them.
This is very common in industrial electrical systems. I couldnt begin to count the number that I have found over the years that others either missed or diagnosed incorrectly.
I have had more than a few electricians doubt what I find. Most of my working career was spent working with and around industrial electricans.
This next statement is not meant to stir the pot but my personal observations concerning electricans there are two kinds one that bends pipe and pulls wire and one that is a control electrican (trouble shooter) and the two are rarely in common. You give me the impression that you are both
You are unfortunately correct. My trade has become diluted with either pipe and wire installers or PLC control technicians. The pipe guys have trouble wiring 3 way switches while the control guys will run 60 foot of SO cord because they can not run conduit.
When I ran large construction projects, I alway kept copies of wiring diagrams for 3 way switches to hand out when we got to the finish stages of the job.:shock:
When I was running maintenance teams, most control electricians thought that industrial work was outside the scope of the NEC. In all honesty, it is a leading cause of electrical breakdowns in plants.
Last year I had 5 tradesman work all of a Saturday on a motor failure (2 mechanics, 3 “electricians”). The replacement motors kept blowing fuses.
The electricians all had associate degrees in electrical engineering and finally came to the conclusion we had a load of bad motors new from the factory. I was in meetings all day and didnt find out until 3 in the afternoon. By then, the purchasing manager had ordered 2 new motors express delivery from Atlanta to get the line going. I went to the line and spent 2 minutes diagnosing the issue and 3 minutes repairing it. The replacement motors were all premium efficiency motors and have a higher inrush current at startup. They will typically blow fuses that would allow a standard efficiency motor to start. This is actually addressed in the NEC, in article 430. However, since they never took time to learn the NEC, they had no idea.:roll:
Stir the pot Charley all you want. It is a very serious issue and you are absolutely 110% right.
Yes I am with you too Charley and William you are so correct in many fields the same thing occurs. No 2 men are equal in knowledge and understanding so you better do your homework before you challenge someone.:mrgreen:
You are welcome Juan. I have read many posts from yourself and you contribute a great deal to the forum.
I believe this is collectively the largest, most valuable, dynamic technical resource available in the home inspection industry and it is made so by all those who share knowledge, wisdom, and experience, such as yourself. Thank you also.
According to 110-3(b) “listed or labeled equipment shall be installed and used in accordance with any instructions included in the listing or labeling” and 110-14(a) states “terminals for more than one conductor shall be so identified”.
The only time two wires can be installed under a single screw or lug is when the terminal is identified for this purpose. Circuit breakers rated not more than 30 amperes are often identified for the termination of two conductors. This can be verified by reviewing the circuit breaker manufacture’s catalog.
Neutral and equipment grounding lugs for panelboards are often suitable for two and sometimes three wires. This information is contained on the label affixed within the panelboard or on the packing container of the equipment ground lug. Often the instructions will identify the number of conductors, the size of the conductors, the conductor material, as well as the torque requirements.
[FONT=Times New Roman]A big misconception is the circuit breaker is installed to protect the load. What the breaker protects is the conductor. I have connected two appliances to one breaker many times and as in this installation the cooktop and oven is allowed to be connected to the same breaker as outlined in 210.19 and the Notes in Table 220.55.
What I meant to say was this.
The overcurrent device is installed to protect the conductor, wire, bus, terminal, but it is not installed to protect the load. The total load determines the size conductor that is used and the size conductor determines the size of the overcurrent device.
In my home I have a clock radio that is plugged into a 15 amp receptacle protected by a 15 amp breaker. The load of the clock radio is .5 amps (1/2 amp). Is that 15 amp breaker protecting that clock radio?
My hall has a 60 watt light bulb that is on a 15 amp circuit. This bulb pulls .5 amps (1/2 amp)is it protected by the 15 amp breaker?
My garbage disposal is a 1/3 HP appliance that is connected to a 15 amp breaker all to itself. This garbage disposal pulls 9 amps. Is the 15 amp breaker protecting this motor?
Yes I am sure that the purpose of the overcurrent device is to protect the conductor not the load.
Edited to add:
I have a circuit that is supplying a 5 amp load. What is the smallest conductor am I allowed to install for this load in a dwelling unit?
What is the largest breaker am I allowed to install on this circuit if I install the smallest conductor allowed?
Answers; The smallest branch circuit conductor I am allowed to install in a dwelling unit is #14 AWG and the largest breaker that can be installed on this circuit is a 15 amp breaker.