Buzzing Sound From Utility Room

A

alyoshak24

Member
Location
Chicago
Occupation
Electrician
Hello Fellow Wizards,

I have a couple of troubleshooting related questions in a paramedical environment.

PROLOGUE: Client called due to hearing a "Buzzing Sound," during normal operational hours, from a utility room that houses all the load centers, electrical enclosures, disco's and pull-boxes.

While this "Buzzing Sound" occurred, client noted that it did NOT have any negative impact to their medical tools, dedicated medical equipment, lighting, outlets or phone systems.

When i arrived to inspect and troubleshoot noise, the manager on shift stated that the "Buzzing Sound" had randomly stopped (however, we all know that these type of problems rarely if ever resolve on their own, especially when they create a "Buzzing Sound" from any electrical enclosure). So the next thing i did was the following:

A. Took note of all medical equipment in continuous use during normal work hours

B. Panel these circuits and breakers are on are labeled as follows: [ Siemens P1 Panel ][ 250A Max ] | [208/120V 3Phase] installed on May 2022. Breakers are of SiemensType HBL / IAC Rating 65KA / HACR Type SWD, 40'C

B1. Total of (4x 20A SP and x1 DP 20A, all #12AWG5 stationary medical appliances/equipment that were used for 3 or more hours which are listed below:
  • Boilers (x3) plugged into 20A gfi on dedicated circuit | 3.5-4.5 hours of continuous
  • Vacuum System DP20A on dedicated circuit and has its own disco next to it with step down transformer | 8 - 9.5 hours of continuous use
  • Duplicator SP 20A plugged into 20A gfi on dedicated circuit | 24/7 hours of continuous
The nameplates for all the equipment calculated at 125% per NEC for continous use arrive at 18A or lower so they are sized correctly.

B2. Next step was to open panel that housed all medical equipment and appliances. After inspection i noticed that 6 circuits had conductors AND breakers that were noticeably warmer than normal, like hot hot to the touch (unfortunately did not have my therm-cam) with a DP breaker (2 out of the 6) was substantially hotter than the other 4 breakers.

//
//

QUESTION(S): My question is as follows:

A. Is it safe to say that "Buzzing Sound" was not a short or a ground fault, but the actual breaker(s) malfunctioning due to the continuous use of the medical equipment described above ?

B. If (A) assertion is erroneous, then what else could cause the "Buzzing Sound" ? (which was made from Utility Room that housed panels, discos and pillboxes)

C. if (A) assertion is agreed upon by majority consensus of wizards. then can i upsize these specific 6 circuits from 20A -> 30A and #12 - > #10AWG ?


Thank you for taking the time to read my question(s), i appreciate all your help and wisdom oh great council of Sages, Priests and Wizards.
 
I would doubt that (A) is the answer and also doubt that there is any real electrical problem. My guess is the magnetic field from the 60 HZ power flow is just making some non current carrying part that is a bit loose vibrate.
 
Any chance you could go back and amp clamp these things during load/business hours? We have IR scanning done on all our switchgear and customer load panels annually, and while some of them do get glowingly warm (at least as far as the IR camera's concerned, anyway), never have we had a 15/20/30 amp circuit feel hot to the touch.
 
Anytime a buzzing sound is heard in electrical panels we go to the source. If in an MCC or control panel then we open the bucket door and look for a contactor or relay and press on the solenoid (armature) to see if the noise stops. It is usually caused by dirt/ grease on the contact surface of the solenoid.
If it is coming from a transformer (control or power) then that is another story.
 
Given the "buzzing" wasn't present when you arrived, part of my questioning would have included how loud was the "buzzing"? Audible from behind the closed door of the electrical room or only upon entry into the room? This would indicated some different level of urgency.

Perception of "warm" by touch not always a good indicator the a breaker is too "warm". A "warm" breaker should first of all have it's current measured for load, is it on the higher end of it's operational limits. GFCI and AFCI breakers will have a "warmer" touch just because of the internal circuitry, and will "warm" adjacent breakers.

Would not ever suggest "C" as an option, no different than the old fuse type the guy would, after multiple fuse blows, just screw in a larger fuse until it no longer blew. If the "warm" breaker is confirmed to be related to a higher and close to the breaker load limit would split the branch circuit into multiple, thus reducing the overall load from the branch, if that was applicable.

These you list as being already individual "dedicated" circuits so have you actually metered for loads? I would also IR for actual heating, where is the breaker getting hot? Are the wires feeding also "warm"? Is the "Warmest" spot at the terminations or the body or nearest the bus connection point?

Have had "older" standard trip breakers "buzz" even with only moderately load within the breaker parameters. Replace the breaker and "buzzing" goes away. Internal spring was getting a little weak allowing the contact to "buzz" and creating heat. Confirmed when I opened the breaker an seen the arc points on the contactor.

alyoshak24 said:
paramedical environment.
Click to expand...
What is this "Environment"?

You list these several loads as "Continuous" with some very significant times.
alyoshak24 said:
  • Boilers (x3) plugged into 20A gfi on dedicated circuit | 3.5-4.5 hours of continuous
  • Vacuum System DP20A on dedicated circuit and has its own disco next to it with step down transformer | 8 - 9.5 hours of continuous use
  • Duplicator SP 20A plugged into 20A gfi on dedicated circuit | 24/7 hours of continuous
Click to expand...
Boilers, Are these electric boilers? Hardly ever would a boiler be considered a "continuous" load. Article 100 definition: "A load where the maximum current is expected to continue for 3 hours or more."
Actually any of the loads mentioned would be hard pressed to fit this definition. If indeed they do then what is the motor or name plate list as the MOD, FLA etc.? Are the motors operating on the equipment rated as "continuous duty"?
 
ModbusMan said:
Any chance you could go back and amp clamp these things during load/business hours? We have IR scanning done on all our switchgear and customer load panels annually, and while some of them do get glowingly warm (at least as far as the IR camera's concerned, anyway), never have we had a 15/20/30 amp circuit feel hot to the touch.
Click to expand...
Hi, I will be going back to take thermal images and take readings with my clamp ammeter and update you with the readings.
 
CoolWill said:
Lighting contactor?
Click to expand...
Could be... at my very first controls-related job, I got to tail our resident wizard in looking at a very old DC-driven freight lift that was making a very LOUD buzzing noise, and tracked it down to a won out contactor. The constant start/stop of current flow might also explain the breaker heating.
 
Fred B said:
Given the "buzzing" wasn't present when you arrived, part of my questioning would have included how loud was the "buzzing"? Audible from behind the closed door of the electrical room or only upon entry into the room? This would indicated some different level of urgency.

Perception of "warm" by touch not always a good indicator the a breaker is too "warm". A "warm" breaker should first of all have it's current measured for load, is it on the higher end of it's operational limits. GFCI and AFCI breakers will have a "warmer" touch just because of the internal circuitry, and will "warm" adjacent breakers.

Would not ever suggest "C" as an option, no different than the old fuse type the guy would, after multiple fuse blows, just screw in a larger fuse until it no longer blew. If the "warm" breaker is confirmed to be related to a higher and close to the breaker load limit would split the branch circuit into multiple, thus reducing the overall load from the branch, if that was applicable. They Are Already Split To Single Dedicated Outlets Or Circuits That Have Stationary Appliances (IE Vacuum Systems, Lathes, X-Rays, Boilers, Duplicators, Water Coolers, Etc)

These you list as being already individual "dedicated" circuits so have you actually metered for loads? I would also IR for actual heating, where is the breaker getting hot? Are the wires feeding also "warm"? Is the "Warmest" spot at the terminations or the body or nearest the bus connection point?

Was There This Past Weekend. Simulated A Work Day and Had 6 Circuits On That They Used Continuously. Did NOT get the same temp results with my Therm Cam, did see some red spots but breakers were not abnormally hot to the touch and were well within heat range. Took readings with my clampmeter and the breakers that dissipated the most heat on the first inspection was the breaker consuming most current (10A on Each Leg). Wires Were NOT warm to the touch during simulation. But the "Warmest" Spots were the actual breakers themselves not wires or busbars.
Click to expand...

Fred B said:
Have had "older" standard trip breakers "buzz" even with only moderately load within the breaker parameters. Replace the breaker and "buzzing" goes away. Internal spring was getting a little weak allowing the contact to "buzz" and creating heat. Confirmed when I opened the breaker an seen the arc points on the contactor. (I have replaced the breakers that were overheating from my initial site visit. Panel was installed in 2022 so these breakers were new. Also electrician who installed these bolt-on breakers overtorqued the ***** out of them because i could not for the life of me remove them)


What is this "Environment"? Dental Office

You list these several loads as "Continuous" with some very significant times.

Boilers, Are these electric boilers? Hardly ever would a boiler be considered a "continuous" load. Article 100 definition: "A load where the maximum current is expected to continue for 3 hours or more."
Click to expand...
Yes these boilers (3 total) are on for at a minimum 3.5 hours M-F, and they have boiling water on at all times to dip in mold casts, so theyre used quite frequently by techs. No Motors on the Boilers just vacuum system and duplicator. I will upload these nameplates once i find them on my usb-drive

Fred B said:
Actually any of the loads mentioned would be hard pressed to fit this definition. If indeed they do then what is the motor or name plate list as the MOD, FLA etc.? Are the motors operating on the equipment rated as "continuous duty"?
Click to expand...
 
CoolWill said:
Lighting contactor?
Click to expand...
upon further investigation, there was actually a lighting contactor enclosure (Square D) Behind the panels in the next room near all the fire alarm and security alarm panels. I missed this on the initial visit. I played around with the controller/time clock to simulate the on/off conditions and tested several times with no buzzing or noise. However to my understanding, these contactors do go bad especially if they are electronically hatched instead of mechanically (which is the case here, the time clock was adjacent to contactor enclosure, and had settings to NC in the morning and NO in the evening). I think this is what they initially heard and assumed it came from the panel because it is literally behind where the panels are installed. However, non of the techs or employees noticed any issues with the lighting so ...idk
 
alyoshak24 said:
Hello Fellow Wizards,

I have a couple of troubleshooting related questions in a paramedical environment.

PROLOGUE: Client called due to hearing a "Buzzing Sound," during normal operational hours, from a utility room that houses all the load centers, electrical enclosures, disco's and pull-boxes.

While this "Buzzing Sound" occurred, client noted that it did NOT have any negative impact to their medical tools, dedicated medical equipment, lighting, outlets or phone systems.

When i arrived to inspect and troubleshoot noise, the manager on shift stated that the "Buzzing Sound" had randomly stopped (however, we all know that these type of problems rarely if ever resolve on their own, especially when they create a "Buzzing Sound" from any electrical enclosure). So the next thing i did was the following:

A. Took note of all medical equipment in continuous use during normal work hours

B. Panel these circuits and breakers are on are labeled as follows: [ Siemens P1 Panel ][ 250A Max ] | [208/120V 3Phase] installed on May 2022. Breakers are of SiemensType HBL / IAC Rating 65KA / HACR Type SWD, 40'C

B1. Total of (4x 20A SP and x1 DP 20A, all #12AWG5 stationary medical appliances/equipment that were used for 3 or more hours which are listed below:
  • Boilers (x3) plugged into 20A gfi on dedicated circuit | 3.5-4.5 hours of continuous
  • Vacuum System DP20A on dedicated circuit and has its own disco next to it with step down transformer | 8 - 9.5 hours of continuous use
  • Duplicator SP 20A plugged into 20A gfi on dedicated circuit | 24/7 hours of continuous
The nameplates for all the equipment calculated at 125% per NEC for continous use arrive at 18A or lower so they are sized correctly.

B2. Next step was to open panel that housed all medical equipment and appliances. After inspection i noticed that 6 circuits had conductors AND breakers that were noticeably warmer than normal, like hot hot to the touch (unfortunately did not have my therm-cam) with a DP breaker (2 out of the 6) was substantially hotter than the other 4 breakers.

//
//

QUESTION(S): My question is as follows:

A. Is it safe to say that "Buzzing Sound" was not a short or a ground fault, but the actual breaker(s) malfunctioning due to the continuous use of the medical equipment described above ?

B. If (A) assertion is erroneous, then what else could cause the "Buzzing Sound" ? (which was made from Utility Room that housed panels, discos and pillboxes)

C. if (A) assertion is agreed upon by majority consensus of wizards. then can i upsize these specific 6 circuits from 20A -> 30A and #12 - > #10AWG ?


Thank you for taking the time to read my question(s), i appreciate all your help and wisdom oh great council of Sages, Priests and Wizards.
Click to expand...
Get proper ppe and use a plug tester to do some preliminary testing, then a meter to test ground to neutral and ground to hots. This will verify that you have at least a ground fault path.
Personally have never been in a quiet electrical room but buzzing is usually consistent.
 
ModbusMan said:
Could be... at my very first controls-related job, I got to tail our resident wizard in looking at a very old DC-driven freight lift that was making a very LOUD buzzing noise, and tracked it down to a won out contactor. The constant start/stop of current flow might also explain the breaker heating.
Click to expand...
This situation is a little different. This is a 120v AC contactor for lighting that is not constantly turning on and off. The conditions are programmed into the time clock and are only TURNING ON ONCE M-F at 6AM and TURNING-OFF ONCE M-F at 6PM. Are the Schneider Contactors
Type LX multipole
lightling, mechanically held, 30A,
10 pole, 600V, 110/120VAC
50/60Hz coil

known to go bust after 3 years ?
 
So i have an update for you guys. NOT sure if this was what caused the noise, but i can say for certain this is what cause some of the breakers to overheat. What i did was the following:

A. Opened the panel covers on both panels and check that every wire was properly terminated. All wires were labeled with white tape and a number corresponding to the directory number and nameplate on actual cover plate, garvin plate, or enclosure/disconnect. One this i noticed immediately is that #17 from Panel "A" was missing but the breaker was there. L/N missing (it corresponds to duplicator machine 20A SP that is on 24/7 with calculated load of 18A after the 125% percent adjustment so still good on wire size and breaker capacity)

B. I noticed #17 from Panel "B" was on same 20A SP and dedicated to 2 outlets that shared medical crockpots that totaled 15A each.

C. Turned of breaker #17 from Panel "B" and it turned off BOTH the crockpots and the duplicator (that was on dedicated circuit on Panel "A")

D. I think i found the issue. Traced where they were tied into to each other at a pullbox above drop ceiling and ran a new line for duplicator to the breaker #17 on Panel "A"

E. Simulated a working environment for 6 hours and noted that the same breakers got warm, they were no were near hot to the touch during my first site visit.

RECAP -- i dont think this is what caused the noise the techs initially complained about but i am pretty certain that these breakers will be operating at a much lower temperature from my initial visit
 
alyoshak24 said:
Hello Fellow Wizards,

I have a couple of troubleshooting related questions in a paramedical environment.

PROLOGUE: Client called due to hearing a "Buzzing Sound," during normal operational hours, from a utility room that houses all the load centers, electrical enclosures, disco's and pull-boxes.

While this "Buzzing Sound" occurred, client noted that it did NOT have any negative impact to their medical tools, dedicated medical equipment, lighting, outlets or phone systems.

When i arrived to inspect and troubleshoot noise, the manager on shift stated that the "Buzzing Sound" had randomly stopped (however, we all know that these type of problems rarely if ever resolve on their own, especially when they create a "Buzzing Sound" from any electrical enclosure). So the next thing i did was the following:

A. Took note of all medical equipment in continuous use during normal work hours

B. Panel these circuits and breakers are on are labeled as follows: [ Siemens P1 Panel ][ 250A Max ] | [208/120V 3Phase] installed on May 2022. Breakers are of SiemensType HBL / IAC Rating 65KA / HACR Type SWD, 40'C

B1. Total of (4x 20A SP and x1 DP 20A, all #12AWG5 stationary medical appliances/equipment that were used for 3 or more hours which are listed below:
  • Boilers (x3) plugged into 20A gfi on dedicated circuit | 3.5-4.5 hours of continuous
  • Vacuum System DP20A on dedicated circuit and has its own disco next to it with step down transformer | 8 - 9.5 hours of continuous use
  • Duplicator SP 20A plugged into 20A gfi on dedicated circuit | 24/7 hours of continuous
The nameplates for all the equipment calculated at 125% per NEC for continous use arrive at 18A or lower so they are sized correctly.

B2. Next step was to open panel that housed all medical equipment and appliances. After inspection i noticed that 6 circuits had conductors AND breakers that were noticeably warmer than normal, like hot hot to the touch (unfortunately did not have my therm-cam) with a DP breaker (2 out of the 6) was substantially hotter than the other 4 breakers.

//
//

QUESTION(S): My question is as follows:

A. Is it safe to say that "Buzzing Sound" was not a short or a ground fault, but the actual breaker(s) malfunctioning due to the continuous use of the medical equipment described above ?

B. If (A) assertion is erroneous, then what else could cause the "Buzzing Sound" ? (which was made from Utility Room that housed panels, discos and pillboxes)

C. if (A) assertion is agreed upon by majority consensus of wizards. then can i upsize these specific 6 circuits from 20A -> 30A and #12 - > #10AWG ?


Thank you for taking the time to read my question(s), i appreciate all your help and wisdom oh great council of Sages, Priests and Wizards.
Click to expand...
Did you check the transformer for the noise?
 
alyoshak24 said:
This situation is a little different. This is a 120v AC contactor for lighting that is not constantly turning on and off. The conditions are programmed into the time clock and are only TURNING ON ONCE M-F at 6AM and TURNING-OFF ONCE M-F at 6PM. Are the Schneider Contactors
Type LX multipole
lightling, mechanically held, 30A,
10 pole, 600V, 110/120VAC
50/60Hz coil

known to go bust after 3 years ?
Click to expand...

I have seen these contactors covered in dust, from the original installation when the covers were left off, which can keep them from closing in correctly. Sometimes it does not take much dust or rust to result in a buzzing noise. Look at the magnet pole faces.
It is also possible that you have a broken shading coil which helps the magnet stayed closed when the voltage waveform crosses zero.
 
jim dungar said:
I have seen these contactors covered in dust, from the original installation when the covers were left off, which can keep them from closing in correctly. Sometimes it does not take much dust or rust to result in a buzzing noise. Look at the magnet pole faces.
It is also possible that you have a broken shading coil which helps the magnet stayed closed when the voltage waveform crosses zero.
Click to expand...
I've only seen the shading coil issue once but dirty rusty or worn faces are frequently the issue. Sometimes a wire brush with a bit of WD40 or similar works. Others are doomed to the junk pile.
 
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