As my friend Jim Seffrin would say “That’s a rich topic.” There is a thread about it based on an IR inspection I did either somewhere here or on the NACBI board.
I have checked loads and I have actually replaced the main breaker and bus in my 200A subpanel thanks to a lightning strike. Sometimes the breaker in the main panel at the pole will trip at other times the breaker at sub in the house will trip.
The short answer is that I don’t have a properly sized service. I should have had at least a 2x150A or 2x200A service. At some point I will convert my two electric resistance heaters to gas and it will cease to be an issue. I converted one of my electric water heaters to a tankless gas unit in 09 and that helped reduce the number of instances to maybe once a year.
BTW: I would treat Sean’s discovery as informational rather than declare it a defect, though the combined load I imagine could be easily duplicated on a winter holiday.
I agree further evaluation needed . First voltage should be checked then load.
AHHH The home should be rated for the built in fixed appliances that can all be in operation at the same time not to say they all will be but they can. Are we to a have a referee throwing red flags saying which appliances can be operated at one time. Not how many portable electric heater you can plug in Jim you are stretching it a bit.
What I find in most cases is when the home has been added on to and the kitchen remodeled with electrical cook stove,electrical water heater added all on a 100 amp panel.
I would of wrote up Shaun’s panel to have it load checked and I do it every time when the load exceedes 80% of its rating
I think the main factor in this one is it was a condo, so there really won’t be any adding on. No hot tub out back either though.
The bottom line is the turd who designed the size for all the units was not considering any of this and cut it down to the wire.
So now I have a 50% chance that if someone else looks at it they could say yeah or ney.
So basically you had a total electric condo no gas in use on a 125 amp main I would still have called it out
The UL standard by which breakers are manufactured says that the rating on the handle of the breaker will hold under the following conditions
600% for two cycles or .033 seconds
300% for two minutes
135% for two hours
As long as the breaker opens sometime within these numbers it meets the UL standard.
Another thing we need to look at is the rating of the service conductors. For a 125 amp service #2 copper conductors is all that is required but for any other installation #2 copper conductors is only good for 115 amps. Or we could use 1/0 aluminum which for any other circuit is only good for 120 amps.
If we look closely at the service calculations for dwelling units we can see that there is a diversity of about 82% given to the size of the load.
This 125 amp breaker and the conductors supplying it are engineered to withstand up to 168 amps of current draw for a period upwards of two hours without any damage to anything.
I don’t see a problem with the installation or the test.
I can see William coming around any minute now to finish off the comment.
I don’t see a problem with the installation or the test.
What if anything do you see wrong?
I don’t see anything wrong because I am not an Electrician.:mrgreen:
Let me rephrase my question. Would you write it up after doing such a test?
No!!!
good answer grasshooper
I don’t see a problem either, especially for a home inspection. I assume he hurried back to the meter after turning on the stovetops and oven before they had time to do a normal cycle off.
I am a little pressed for time right now so I can’t go into a detailed explanation. However, as others have said, going by the information presented thus far, there is nothing wrong.
Load calculations are easy enough to do to do with my Residential Electrical Service Size Calculator. It is available to download free from my software repository.
The calculator is a simplified version of one that I created for training electricians. I created this version specifically for home inspectors. All you have to do is plug in some basic information.
125A would be the next standard size so it is OK. There is nothing to be concerned about.
The service is sized based on demand load. The demand load compared to percentage of potential maximum load will vary from one building to another. So, as an example, the demand load in one building could be 60% of the potential maximum load in one building but 90% in another.
[FONT=Verdana]In a sense, you could say that yes, there is a referee - sort of. This is one of those areas where what the NFPA does is as much descriptive as it is proscriptive. The load calculations may not be perfect but they are based on statistical research done over many decades. The calculations haven’t changed much in a while but they do change from time to time as the way we use electricity changes.
You could think of it like a car with a tachometer versus the same car without a tachometer. The tachometer will have a red line indicating that the engine RPM is too fast but the engine doesn’t blow up the instant the needle reaches the red line. Over time, your engine speed and driving will average out. Consequently, the engine’s maximum temperature will average out. Electrical systems are designed the same way. Just as you can intentionally push a car’s engine to the point where it blows up, you can push an electrical system to the point where it shuts down. However, under normal operation, loads go on and off and the system is rarely over taxed. When it is, the circuit breakers do their job.
If you have a tachometer, you can keep an eye on your engine speed. But what if you don’t have a tachometer? The engine is designed to hold up under a normal range of operation. There is also a safety buffer designed into it. Electrical systems have a lot of safety buffer built into the overall design and the individual components. The idea is to have the system being like the car without the tachometer. You don’t have to keep on eye on it constantly. The system is designed to operate normally with short duration overloading.
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Thanks George.
I still have mine but have never used it for Inspections George.