Fieldpiece SMG5 Digital Megohm Meter — HVAC/R Compressor Insulation Testing
The Fieldpiece SMG5 is a compact standalone megohm meter designed for checking insulation resistance in HVAC/R compressors, motors, and transformers. It applies a 1,000V DC test voltage to stress the insulation and measures resistance up to 2,000 megaohms — detecting high-resistance problems caused by moisture, contamination, and insulation degradation that a standard multimeter cannot identify.
A standard digital multimeter applies less than 1V to test resistance and delivers only a few milliamps — not enough voltage to detect the high-resistance insulation faults that indicate moisture ingress or contamination. A megohm meter (megger) is the correct tool for this test. The SMG5 is a compact, field-ready option for HVAC/R technicians who need to check compressor insulation condition before condemning or replacing a compressor.
Insulation resistance testing on live or energised equipment is dangerous. Confirm the system is de-energised and isolated before testing. Electrical testing requires appropriate trade qualifications and licensing — confirm requirements with the relevant authority in your state or territory. Confirm all specifications against the Fieldpiece SMG5 datasheet.
Key Features
- 1,000V DC test voltage — stresses insulation to detect high-resistance faults
- Measures insulation resistance up to 2,000 megaohms
- Maximum current output: <1mA
- Suitable for winding-to-ground insulation testing on motors, compressors, and transformers
- Backlit LCD display
- Auto power-off to extend battery life
- Compact standalone design
- 1-year warranty
What’s Included
- Fieldpiece SMG5 Megohm Meter
- 2 x probe tips
- 1 x ground lead with detachable tip
- 1 x alligator probe tip
- Carrying case
- 4 x AAA batteries (installed)
- Operator’s manual
Best For
- HVAC/R technicians checking compressor insulation resistance before condemning or replacing a compressor
- Winding-to-ground insulation testing on motors and transformers
- Detecting moisture ingress and contamination in insulation that a standard multimeter cannot identify
Check Before Ordering
- Insulation resistance testing must be performed on de-energised, isolated equipment — confirm isolation before testing
- Electrical testing requires appropriate trade qualifications — confirm licensing requirements in your state or territory
- Confirm all specifications against the Fieldpiece SMG5 datasheet for your application
- Warranty: 1 year — confirm current terms at time of purchase
Frequently Asked Questions
Why can’t I use a standard multimeter for insulation testing?
A standard multimeter applies less than 1V and only a few milliamps — not enough to detect high-resistance insulation faults caused by moisture or contamination. A megohm meter applies 1,000V DC to stress the insulation and reveal faults that a multimeter will miss.
What is a safe insulation resistance reading for an HVAC compressor?
Confirm acceptable insulation resistance values with the compressor manufacturer’s documentation and your relevant trade authority. Do not rely on general rules without verifying against manufacturer specifications.
What is the warranty?
1 year. Confirm current terms with HVAC Trade Supply at time of purchase.
Browse our full Fieldpiece test and measurement range or contact our team for advice.