As an Amazon Associate, Akermin earns from qualifying purchases. Product links on this page are affiliate links.
A handheld digital multimeter can tell you that an earth conductor is present, that it is connected to the supply earth, that a protective conductor is continuous on a dead circuit, and that polarity at an outlet is right. It cannot measure earth electrode resistance and it cannot measure earth fault loop impedance, which are the two quantities a certificate asks for. Both of those require an instrument that pushes a known current through the path under test, and a multimeter only watches. So the honest scope of this job is confirmation, not verification: the meter tells you whether something is obviously wrong, and a loop tester tells you whether it is good enough.
What a handheld meter can confirm about an earth
Separate the three questions that hide inside the phrase checking earthing. The first is whether an earth exists and reaches the point you care about, which is a connectivity question. The second is how good the connection from the installation to the general mass of earth is, which is an electrode resistance question. The third is whether enough fault current would flow to operate the protective device fast enough, which is a loop impedance question. A multimeter answers the first well and the other two not at all.
That first question is not trivial, and answering it catches real faults: a disconnected earth at a socket, a protective conductor cut during plastering, a metal enclosure that was never bonded, a reversed line and neutral. Those are the faults a meter finds in minutes. Before starting, be clear about which checks are live and which are dead. The dead ones need the circuit isolated and proved dead with a two pole indicator, not with the meter you are about to use for measurement. The live ones expose you to mains and in many places are regulated work, and nothing below is a substitute for a competent person with the right instruments.
| What you want to know | Instrument that measures it | What a handheld multimeter gives instead |
|---|---|---|
| Electrode resistance to the mass of earth | Earth resistance tester, fall of potential with spikes, or a clamp on earth tester | Nothing usable, a two terminal ohms reading is a different quantity |
| Earth fault loop impedance | Loop impedance tester that injects a test current | Nothing, the meter has no current injection |
| Earth present and connected to supply earth | Multimeter on AC volts, live, competent person only | Line to earth near nominal, neutral to earth near zero |
| Protective conductor continuity, dead circuit | Low resistance ohmmeter with a defined test current | An ohms reading whose resolution may be coarser than the limit |
| Polarity at an outlet | Multimeter on AC volts, or a socket tester | Fully capable, this is the strongest check it offers |
| Is the earth carrying current it should not be | Clamp meter around the protective conductor | Not possible without breaking the conductor |
Why two leads and an ohms range cannot measure an electrode
An ohmmeter drives a small current out of one lead and measures the voltage it develops, then divides. For that to describe an electrode you would need the current to return through the soil from the general mass of earth, and you would need a voltage reference planted far enough away to be outside the resistance area of the electrode. A two terminal measurement has neither. Whatever it displays is the resistance of a loop you did not intend to measure, usually dominated by your own leads and the contact at each clip.
The fall of potential method exists for this reason. A tester injects current between the electrode and a remote current spike, measures potential at an intermediate spike, and derives the resistance of the electrode alone, which is why earth testers come with long leads and spikes in the case. Loop impedance is a different measurement again: the tester briefly draws a substantial current through the line and earth path and watches the voltage sag, from which the impedance of the whole loop including the supply transformer follows. The design target is arithmetic you can do once you have that number, since the fault current is the supply voltage divided by the loop impedance and the protective device has to clear it inside a stated time. You cannot get there without the measurement, and no setting on a multimeter produces it.
The three voltage checks at a socket, and what each one rules out
With the outlet live and the meter on AC volts, three readings between the three terminals are informative together in a way none is alone. Line to neutral should be near nominal supply voltage, which confirms the circuit is energised and gives you the yardstick for the next reading. Line to earth should be close to that same figure; a result well below it suggests a high resistance earth path, and a result near zero usually means there is no earth reference rather than a perfect one. Neutral to earth should be small, because the two are bonded at the supply, and anything substantial points at a loose or borrowed neutral.
Instrument features start to matter here. Capturing a reading in an awkward position is easier with hold, and watching whether a voltage wanders is easier with a minimum and maximum memory. The Fluke 177 true RMS multimeter states hold and auto hold, minimum, maximum and average memory, 6000 counts, and an analogue bar graph that updates forty times a second, which is the feature that shows an unstable connection as a twitching bar while the digits look settled. Its safety category rating is Not stated in the listing bullets, which on live work is a specification you should not have to guess at. Why the AC conversion method matters for any reading taken near a drive or a switching load is covered in what is true RMS on a multimeter.
Continuity on a dead circuit, and the resolution floor that defeats it
With the circuit isolated and proved dead, continuity of a protective conductor is a genuine multimeter job, subject to one arithmetic problem. Limits for protective conductor continuity live in the region of a fraction of an ohm, and a handheld meter whose lowest ohms range resolves in tenths of an ohm cannot distinguish 0.05 ohms from 0.15. Add the resistance of the test leads themselves, commonly a tenth of an ohm or more, and the thing you are trying to measure is smaller than the noise you are measuring it with. Null the leads first by shorting the probes and either subtracting or using a relative mode, and treat any result in the same order as the lead resistance as unmeasured rather than measured.
Two instrument features address this properly. One is a four wire technique, which separates the current carrying leads from the voltage sensing leads so that lead resistance drops out of the result; the Fluke 8808A bench multimeter states that technique alongside 5.5 digit resolution and dedicated DC leakage current measurement. The other is simply more digits, and the Hantek HDM3065X states 6.5 digit resolution with up to 30,000 readings per second and trend plotting. Both are bench instruments, which is the next problem. For what counts and digits buy you in general, see what is resolution in a digital meter.
Category ratings and why a bench meter stays on the bench
Measurement category describes the transient energy an instrument is built to survive, not its precision. Category II covers appliances and socket circuits, category III fixed installation and distribution boards, category IV the origin of the installation and the supply side. A precise instrument with no category rating for the position you are standing in is the wrong instrument, however many digits it has, because the failure mode is not a wrong reading.
The Neoteck clamp multimeter states category III at 1000 volts and category IV at 600 volts, true RMS, a low impedance mode to suppress ghost voltage, inrush current capture, non contact voltage detection, 1000 amps AC and DC through a 40 mm jaw, and a 9999 count colour display. Those ratings, and the jaw, are what make an instrument appropriate at a distribution board. They also enable a check a probe meter cannot do at all: clamping the protective conductor to see whether it is carrying current under normal conditions, which is how a borrowed neutral or an insulation fault announces itself. The bench instruments above publish no measurement category in their bullets and one of them is described at 120 volts, so neither belongs anywhere near a consumer unit. Choosing between these classes is covered in how to choose a digital multimeter, and the naming confusion that surrounds the category is visible in the VEYFIY solar panel tester review.
Knowing when to stop and reach for a loop tester
Stop and escalate on any of these: line to earth reading substantially below line to neutral, a neutral to earth voltage of more than a few volts, a protective conductor whose continuity you cannot resolve against the limit, any sign of current in an earth conductor, or an installation with no visible main protective bonding. Each of those is a finding a multimeter can legitimately produce and none of them is something a multimeter can quantify. The useful mental model is that the handheld meter is a screening tool: it is good at telling you that something is wrong and poor at telling you that everything is right. A certificate needs the second, which needs the instruments that inject current, and the gap between those two statements is the honest answer to the question this page started with.
Frequently Asked Questions
Can a multimeter measure earth resistance?
Not the quantity that matters. Earth electrode resistance is the resistance from a conductor through soil to the general mass of earth, and measuring it requires driving a current through that path with reference spikes placed at a distance. A two terminal ohms range has neither the current path nor the reference.
What should line to earth read at a socket?
Close to the line to neutral voltage, within a few volts. A reading far below that suggests a high resistance earth connection, and a reading near zero suggests no earth reference at all rather than a perfect one.
What should neutral to earth read?
A few volts at most on a loaded circuit, and close to zero on an unloaded one, because neutral and earth are bonded at the supply. A substantial neutral to earth voltage points at a loose neutral or a borrowed neutral and is a reason to stop.
Why does continuity testing need a specific test current?
Because a low test current can read through a dirty or oxidised joint that would fail under fault conditions. Dedicated low resistance ohmmeters push a defined current, commonly around 200 milliamps, so that a marginal joint reveals itself.
Is it safe to do these checks myself?
The dead ones, on a circuit you have isolated and proved dead, are routine. The live ones are not, and in many jurisdictions work on an installation is regulated. If a check suggests a fault, stop and bring in someone qualified with the right instruments.