I received a call from a property owner who has a an un occupied commercial suite that has a seemingly high electric consumption. The owners shut of all the branch circuit breakers and say that the meter is still turning. They contacted the utility company and their response was to get an electrician that there is a "grounding problem" somewhere. I realize that this is vague info at best, does "grounding" sound like a reasonable place to start looking. Any suggestions appreciated.
Electric consumption/ circuit breakers off.
- Thread starter nizak
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DownRiverGUy
Member
- Location
- Canton, MI
Is there a Building Owner owned Transformer prior to hitting the panel? Depending on the size that may cause a sizeable draw just by being energized.
Mayimbe
Senior Member
- Location
- Horsham, UK
If all the breakers are switched off, and there is electric consumption happening. I would check this things:
1. Check if the breakers are actually interrupting the current flow.
2. It could be that somewhere near the electric consumption meter theres high impedance failure or short circuit and the protections are not detecting it.
3. If the commercial is unoccupied, What could be possibly consumming electricity? If you find it, then disconnect it. In a rude angry way :grin:
Mayimbe
Senior Member
- Location
- Horsham, UK
Mayimbe
Senior Member
- Location
- Horsham, UK
Not true. It is possibly true for a low impedance fault.
..."The type of faulted condition in this study is the one that appears
?invisible? to conventional fault detection methods and is caused by a leakage or small current that flows through surrounding objects that present high impedance in the current path to ground. These kinds of faults are hard to detect by monitoring equipment because their presence result only slight increases in load current; thus can be confused with a normal increase in load."
from "Modeling, Detection, And Localization of High-Impedance Faults In Low-Voltage Distribution Feeders" by Fabian Marcel Uriarte
http://scholar.lib.vt.edu/theses/available/etd-01052004-125535/unrestricted/ThesisMasterFabianUriarte.pdf
Mayimbe
Senior Member
- Location
- Horsham, UK
so the current could be between 30-15 amp. Assuming that it is continuous in the 15 day period.
if it is continous trough that period, there are high chances of being a high impedance fault.
if it isnt continous, it could be a power theft like jghrist said.
meanwhile, do an energy audit or cut off the service.
LarryFine
Master Electrician Electric Contractor Richmond VA
- Location
- Henrico County, VA
- Occupation
- Electrical Contractor
It should be easy enough to trace with a wiggy, and maybe a clamp-on ammeter. There has to be a voltage if there's a current.
You need access at every point from the meter to the panel to check for voltage where there shouldn't be any. Where's the main?
You need access at every point from the meter to the panel to check for voltage where there shouldn't be any. Where's the main?
A small current wouldn't dissipate 3700W. Dissipating 3700W in a small area will cause a high temperature.
Mayimbe
Senior Member
- Location
- Horsham, UK
whats a small current for you?
to me 30 Amp seems to be a small current.
besides, we dont know the wire sizes of the feeders. Neither whats happening on this suite that OP is talking about.
and finally, this statement
"A high impedance fault that consumed significant power would cause a fire."
is not true as i said before. and it has nothing to do with the scenario of the OP
LarryFine
Master Electrician Electric Contractor Richmond VA
- Location
- Henrico County, VA
- Occupation
- Electrical Contractor
30a on a service with all circuits off is not a small current.
whats a small current for you?
to me 30 Amp seems to be a small current.
I never saw a main disconnect mentioned, by the way.
Allen Schafer
Member
Sounds like the owners lighting
Pierre C Belarge
Senior Member
- Location
- Westchester County, New York
whats a small current for you?
to me 30 Amp seems to be a small current.
besides, we dont know the wire sizes of the feeders. Neither whats happening on this suite that OP is talking about.
and finally, this statement
"A high impedance fault that consumed significant power would cause a fire."
is not true as i said before. and it has nothing to do with the scenario of the OP
What do you base this statement on?
dbuckley
Senior Member
- Location
- Canterbury, New Zealand
I'd have thought 3700 watts being dissapated in a small area where it ought not to be is a significant risk of fire. Distribute that 3700W over a few hundred square metres, and its a non-issue.
Cow
Senior Member
- Location
- Eastern Oregon
- Occupation
- Electrician
- Location
- San Francisco Bay Area, CA, USA
- Occupation
- Electrical Engineer
I'd go take a walk around the place and smell for pot plants. When growing they produce a distinct odor. Here in California, scenarios like yours were* a common way for Law Enforcement to find the indoor growers. They usually try to tap off ahead of the main breakers if they can, and even try to tap off ahead of meters. But some are not sophisticated enough to do that and just tap in where they can. 3.7kW s not really a lot of power for a sophisticated grower, but it does fit with a teenager who is just starting out and hasn't figured it all out yet.
http://www.electricityforum.com/news/nov09/Cuttingoffpowrtopotgrowers.html
* Past tense, because now they don't chase them much any more, but they will prosecute for the power theft...
http://www.electricityforum.com/news/nov09/Cuttingoffpowrtopotgrowers.html
* Past tense, because now they don't chase them much any more, but they will prosecute for the power theft...
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