The MA145 by Extech is a compact clamp meter that boasts AC and DC measuring capabilities and a non-contact voltage detector. This is a well designed amp clamp with a CAT-III rating that can measure up to 300A. It is best for DIY, around the house usage and ships with carry case and cell batteries.
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- Compact jaw size (0.8″)
- Zeroing for accurate measurements
- Voltage detector
- Auto sense
- Low pass filter
- Data ‘Smart’ hold
- Auto power off
- Carry case
- Size: 2.4″ x 5.8″ x 1.2″
- Weight: 4.9oz
- Clamp meter
- 1.5V batteries (LR‐44)
Note: test probes not needed
In-depth Review of the Extech MA145
This is solely an amp clamp, where you get to measure amperage. You will probably see others out there that come with test leads attached and a dial like a traditional multimeter. With these, you can basically measure what a standard meter would – voltage, resistance, continuity – with the addition of higher amperage testing.
While the Extech MA145 lacks this dual usage, on the flip side it is easy to use and is more compact as a result. Jaw size is less than an inch, which would allow you to clip around a 150mm² core (single cable). It can measure to 300A, though it is unlikely those who purchase this device would be around those sorts of amperages, outside of the automotive industry at least.
The controls step between amps, voltage (non contact), low pass filter and hold function, while the dual central power button also operates the backlight. The MA145 is fairly accurate, yet, like all amp clamps, will struggle with accuracy at low voltage/amperage signals.
Non‐contact voltage detection: This allows you to pick up AC voltages from 80V to 600V, so is good for mains and three phase supplies in both the US and Europe. You won’t get an accurate voltage reading on the display with this, however; more an indication through a beeper and display dashes. Quicker beeps and more dashes signify higher voltage. Note: never rely on this when working with mains voltage.
The Extech MA145 comes with a carry pouch with natty belt loop.
|AC current||60A / 300A||±(1.5%+25) @60A||0.01|
|DC current||60A / 300A||±(1.5%+5) @300A||0.1|
|Low pass filter||60A||±(3.5%+25) <3A||0.01|
|Low pass filter||300A||±(3.5%+5) >3A||0.1|
|Non-contact EF||80 to 600V AC|
|Max jaw/conductor||0.87"(22mm) / 150mm² core|
The build is about what you’d expect from a $100 clamp/meter – quite tough, with a drop test success to four feet. The interface is nicely designed, being minimalist, smooth and straightforward. There are no cables to review as this is clamp-only.
Display: The display on the Extech MA145 is nice and large and is easily read. It is 6,000‐count resolution and can update at a semi-respectable two times a second. It is backlit and has over‐range and low battery indicators.
Function and Performance
Don’t expect fireworks. This is a basic device that doesn’t have huge resolution or update speeds, though it does the job well enough for most uses. Functions include an auto power-off (after 20 minutes) to save on juice. This is handy since the batteries are fragile – the LR‐44 coin cells deliver an average battery life of around 20 hours, which is a lot less than your typical multimeter.
Other functions include a low pass filter (160Hz cut off) for testing vary speed drives, example. An inrush mode will let you measure the current drawn by a starting motor, with 5A detection and 100ms sample window. There is also smart data hold and an auto-sense feature.
Safety: As the MA145 is an amp clamp it does not need to be internally fused. Category rating is CAT-III at 600V.
Pros and Cons
- Can measure DC as well as standard AC
- EF voltage detection
- Nice and compact
- No leads to worry about
- Well made
- Reasonable price
- Limited use
- Board quality could be better
An ideal little clamp meter for its intended use, the Extech MA145 can measure AC and DC amperage and is ideal for odd jobs. Its small jaws allow users to get into tight spaces better, though it is not suited to heavy duty, factory-based environments.
Alternatives: The Klein Tools CL800 is a similar device from a respected brand that will also measure voltage, continuity and temperature, while the Fluke 325 is one of the best out there. If you don’t need DC amps, have a look at the cheaper Etekcity MSR-C600.