I'm working in an approximately 20000 square foot office building and entered the electrical/data closet which is housing a transformer fed from outside the building in the area of the meter pan. It's 99 degrees outside, and I haven't gone to look at the configuration of the service fed. The transformer is humming quite loudly, and the guy who sits adjacent to the closet is half deaf (too much Zep or the Oz I suppose). Question is....should this transformer be humming loudly, and yes I know...the volume is subject to interpretation and I have no means to measure the dB level. AC is cranking and the lights are on, but there's a handful of folks here right now and I'm suspecting power usage is limited other than the lights and AC. Is this hum normal, or should action be taken to do further analysis?
Transformer Hum
- Thread starter Jons
- Start date
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chris kennedy
Senior Member
- Location
- Miami Fla.
- Occupation
- 60 yr old tool twisting electrician
First thing I would check, were the shipping bolts loosened at the time of installation.
Attachments
ggunn
PE (Electrical), NABCEP certified
- Location
- Austin, TX, USA
- Occupation
- Consulting Electrical Engineer - Photovoltaic Systems
Dinah-Moe hum, Dinah-Moe hum
Where's this Dinah-Moe comin' from?
- Uncle Frank
Where's this Dinah-Moe comin' from?
- Uncle Frank
scootk70
Member
- Location
- Allentown, PA
kwired
Electron manager
- Location
- NE Nebraska
- Occupation
- EC
Is it transferring any vibration to anything it is attached to? That can amplify the sound to some degree. Rigid wiring method between the transformer and the wall could make a large portion of the wall resonate that sound.
- Location
- San Francisco Bay Area, CA, USA
- Occupation
- Electrical Engineer
How loud is quite? Hot hot is purdy? This transformer is rated for 150C rise over ambient, 220C max. 220C is 428F, so is it over 400 degrees Fahrenheit? If not, don’t worry about it.
As to the sound, the standard that applies to transformer noise in NEMA ST-20, which states that a transformer this size should not be noisier than 45dB. As a comparative example, a common refrigerator hum is 40dB, a vacuum cleaner is 50dB. So if it’s louder than a vacuum cleaner, it’s worrisome but if it’s not as annoying as a refrigerator, it’s normal.
As to the sound, the standard that applies to transformer noise in NEMA ST-20, which states that a transformer this size should not be noisier than 45dB. As a comparative example, a common refrigerator hum is 40dB, a vacuum cleaner is 50dB. So if it’s louder than a vacuum cleaner, it’s worrisome but if it’s not as annoying as a refrigerator, it’s normal.
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