20 amp devices on 25 amp breaker

Status
Not open for further replies.
A

AEFAC

Member
Location
Montana
Hello,
Any help would be awesome. Was wondering if there are any exceptions that let you put 20 amp rated devices on a 25 amp breaker with #10 wire? We will have 3 20 amp 240 v receptacles on one circuit. Each receptacle will have a continuous load of 5.6 amps from a computer that is plugged into it. It puts us just over 80% on the circuit, and we have been having issues with breakers tripping.
Thanks
 
AEFAC said:
Hello,
Any help would be awesome. Was wondering if there are any exceptions that let you put 20 amp rated devices on a 25 amp breaker with #10 wire? We will have 3 20 amp 240 v receptacles on one circuit. Each receptacle will have a continuous load of 5.6 amps from a computer that is plugged into it. It puts us just over 80% on the circuit, and we have been having issues with breakers tripping.
Thanks
Click to expand...


Just wondering how has it been determined that this a continuous load? Even if left on 24/7 a computer is not a continuous load.
 
infinity said:
Just wondering how has it been determined that this a continuous load? Even if left on 24/7 a computer is not a continuous load.
Click to expand...
I was always thinking PC is a continuous load
 
m sleem said:
I was always thinking PC is a continuous load
Click to expand...

By definition in Article 100 it would need to operate at it's maximum current for 3 hours or more. That means that for a computer it would need to be running at it highest output for the video card, the sound card, its maximum CPU cycles and every other computer function at the maximum level for that time period.
 
Will try to answer everything here.
First I was not able to find any exception, but wasn't sure if there was some exception somewhere that I had over looked.

Panels are all maxed out for breaker space, everything is bolt on so no tandems.

Each computer is a continuous load for sure. They are mining Bitcoins and the computers are always at max draw 24/7. (If you want to get a little confused just dig into Bitcoin mining)

Had not thought about the PDU angle, will look into that.

Thanks All
 
Where are you getting the computer load data? From the nameplate - OR - actual load measurement? Never seen a computer come close to it's nameplate load, bitcoins not withstanding.

RC
 
Actual load measurements in the field, the miners (computers) are a little different than standard computers and run at full power all the time.

The reason the breakers are tripping is that the panel is filled with breakers that are also running at the max. The 200 amp panel is loaded up to 150 amps continuous, and when I say continuous I mean 24/7 365. The only time these things turn of is if there is a power outage. After we opened the panel door and got a little fresh air coming into the building the breakers seem to be holding. We also are in northern Montana and it's cold this time of year. Once summer hits it's not going to be so easy to keep the temp down, and we will be back to our high temps in the panel.
 
AEFAC said:
Actual load measurements in the field, the miners (computers) are a little different than standard computers and run at full power all the time.

The reason the breakers are tripping is that the panel is filled with breakers that are also running at the max. The 200 amp panel is loaded up to 150 amps continuous, and when I say continuous I mean 24/7 365. The only time these things turn of is if there is a power outage. After we opened the panel door and got a little fresh air coming into the building the breakers seem to be holding. We also are in northern Montana and it's cold this time of year. Once summer hits it's not going to be so easy to keep the temp down, and we will be back to our high temps in the panel.
Click to expand...

If your having those kinds of issues your adding to it will only increase the problems, and, the small percentage above full load on the branch circuit your adding would be the least of the worries.

JAP>
 
Another thing to consider with the type of load involved is harmonics effects. If your current measurement is not a true RMS measurement - you may not have what you think you have for heating effects.
 
Status
Not open for further replies.
Top