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Electric motor lubrication schedule & oiling ports:
This article explains the typical lubrication requirement for for motors found on HVAC equipment in buildings such as air conditioners, furnace or air handler blower fans, oil burner motors, well pumps, and condensate return pumps. While some motors are permanently lubricated, others require lubrication as often as annually, depending on the motor usage level.
A simple check of the motor's data tag, explained here, can give the lubrication requirements needed to keep the motor running reliably and safely.
Electric Motor Lubrication Specifications & Schedules: when, how much oil, where to oil
The two approaches to lubricating the moving parts of an electric motor are:
Permanently-lubricated electric motors: the motor has no oiling ports, has sealed lubricated bearings installed at the factory. Watch out: this motor should not be oiled. Doing so may damage the motor.
Duty-cycle based manually lubricated electric motors: these motors require maintenance according to how much they are in use (their duty cycle) and will have oiling ports, usually an open tube or an openable metal cap at either end of the motor.
Here are Beckett's (1989) recommended motor oiling intervals:
Air Conditioner, Heat Pump, or Heating System Electric Motor Lubrication Schedule
Explanation of electric motor duty cycle
Lubrication Frequency (Years)
Occasional Duty Electric Motors
Motor runs less than 2 hours per day
Intermittent Duty Electric Motors
Motor runs 2-12 hours per day
Continuous Duty Electric Motors
Motor runs 12 or more hours per day
Permanently-lubricated Electric Motors
No oil ports, factory-sealed pre-lubricated bearings
At ELECTRIC MOTOR DATA TAG we explain all of the information that can be found on the electric motor data tag, including the motor's lubrication requirements.
How much oil is required when lubricating an electric motor? The answer is I can't say because the quantity varies according to the motor design.
For the oil burner motor whose data tag is illustrated at the top of this page, re-oil instructions specify that each bearing is to be lubricated with 150 drops (about one teaspoon) of SAE 20 oil.
Watch out: Lubrication should be with an oil and at frequency specified by the equipment manufacturer. If you don't have this data use the table above. Lubrication typically is with SAE 20 oil, droplets or tube-fed into the motors (usually two) oiling ports.
Watch out: Do not soak the motor in oil, do not spray the motor windings with spray oils like WD40, do not try to lubricate permanently-lubricated motors that don't have an oil port.
Watch out: if the motor's data tag indicates that it is permanently lubricated or does not require lubrication, don't try to lubricate it - you're likely to cause damage or even an unsafe motor.
How & Where to oil an electric motor
Reader Question: where are the lubrication points for an electric motor such as the Emerson K55hxkwa-9803 ?
(July 23, 2014) Jeff Wilmsmeier said:
Can you oil a Emerson K55hxkwa-9803
Jeff I had trouble finding a manual for this fan motor online too - so I don't know the answer.
Look closely at the motor assembly. Oil ports will be obvious, often capped with a hinged cap or a hole facing up marked "OIL" on the steel body of the motor.
Or send us some sharp photos of all sides of the motor and we'll comment further.
Below we illustrate three electric motors, all happening to be found in heating furnace blower compartments.
At below left we see an electric motor that is permanently-lubricated or factory-lubricated. There are no visible oiling points. Oil points on a typical electric motor such as these furnace blower motors will be visible as a small metal cap that opens on a vertical tube that directs a few drops of proper lubricating oil onto the motor's bearing and shaft end (red arrow, below-right).
Other older electric motors may also have oiling points without the vertical lubricant directing tube, just a rubber or metal cap over the oil insertion point such as shown in our photo at below left (blue arrow).
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Simpson 260® Series 6XLM
Volt-Ohm-Milliammeter Instruction Manual, retrieved 9/5/2012, original source: http://www.simpsonelectric.com/uploads/File/datasheets/260-6xlm.pdf, [copy on file as Simpson_260-6xlm.pdf]
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 Dr. Jess Aronstein, consulting engineer, Poughkeepsie NY, 1991 firstname.lastname@example.org
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 ASHI Technical Journal, Vol. 2. No. 1, January 1992, "Determining Service Ampacity," Dan Friedman and Alan Carson,
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with subsequent updates and additions to the original text ongoing to 2/19/2006. Reprints of the originals and reprints of the Journal are available from ASHI, the American Society of Home Inspectors www.ashi.com.
 "Electrical System Inspection Basics," Richard C. Wolcott, ASHI 8th Annual Education Conference, Boston 1985.
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 "Electrical System Inspection Basics," Richard C. Wolcott, ASHI 8th Annual Education Conference, Boston 1985.
 "Home Wiring Inspection," Roswell W. Ard, Rodale's New Shelter, July/August, 1985 p. 35-40.
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 Jim Simmons: Personal communication, J. Simmons to Daniel Friedman, 9/19/2008. Photographs contributed to this website by Jim P. Simmons, Licensed Electrician, 360-705-4225 Mr. Electric, Licensed Master Electrician, Olympia, Washington Contact Jim P. Simmons, Licensed Master Electrician, Mr. Electric, 1320 Dayton Street SE
Olympia, WA 98501, Ph 360-705-4225, Fx 360-705-0130 email@example.com
 Kenneth Kruger: Original author of the sidebar on testing VOM DMM condition: Kenneth Kruger, R.A., P.E. AIA ASCE, is an ASHI
Member and ASHI Director in Cambridge, MA. He provided basis for this article penned by DJ Friedman.
 LB Miller, "A simple Do-It-Yourself test fixture that will allow you to measure the DC resistance (Rm) of RC Model Electric Motors", San Marcos C, HobbyKing.com, retrieved 9/12/12, original source: http://www.rcgroups.com/forums/showthread.php?t=580151 [copy on file as Miller_Test.pdf]
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 Wikipedia provided background information about some topics discussed at this website provided this citation is also found in the same article along with a " retrieved on" date. NOTE: because Wikipedia entries are fluid and can be amended in real time, we cite the retrieval date of Wikipedia citations and we do not assert that the information found there is necessarily authoritative.
WikiHow: "How to Check Out an Electric Motor", retrieved 9/12/12, original source: http://www.wikihow.com/Check-an-Electric-Motor
 Andy Page, "The Basics of Motor Circuit Analysis", Reliable Plant, (Noria Corporation), 1328 E. 43rd Court, Tulsa, OK 74105
Tel: 800-597-5460; Email: firstname.lastname@example.org, retrieved 9/13/12, original source: http://www.reliableplant.com/Read/10686/motor-circuit-analysis, [copy on file as Page_Andy_The basics of motor circuit analysis.pdf] - Quoting:
MCA online [tests performed while the motor is operating] can be further split into two categories - current analysis and voltage analysis. Current analysis is primarily focused on the rotating components. Loose or broken rotor bars, cracked end rings, rotor eccentricity, misalignment and coupling/belt problems are some of the "big-hitter" failure modes detected in the current signature. Power quality issues like harmful harmonics, voltage imbalances and under/over-voltages are among the issues identified with voltage analysis.
MCA offline is most famous for the resistance-to-ground measurement. But other measurements make motor circuit defects easy to find. Measuring electrical characteristics like impedance, inductance and capacitance tell the analyst plenty about the condition of the windings. Inductance is a great indicator of turn-to-turn shorts. Capacitance to ground measures the amount of winding contamination (water, dirt, dust, etc.). Changes in each of these affect impedance (total resistance of an AC circuit). These characteristics are measured phase to phase and phase to ground and compared to each other and to percent change from baseline to identify motor circuit defects.
Motor circuit analysis (MCA) is often and easily confused with motor current analysis (MCA), which is an abbreviated version of motor current signature analysis (MCSA).
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