I have a small question for everyone in this thread: do your lightbulbs have a CAT rating on them? When you twist a bulb into its socket, do you ever worry about it exploding in your hand? Do you wear safety glasses and rubber shoes when you change a lightbulb?
A DMM may be connected to the mains for a few seconds at a time to take a reading, and there is only one of them. All the lamps in your house are connected to the mains 24/7 and switched on for hours at a time. They could explode, cause a fire, or cause human injury. The risk is vastly higher than with using a DMM.
Why are there many threads about meters, and no threads about household appliances and electrical devices? There are millions more of the latter, and a proportionately higher hazard, statistically.
Appliances have a legal path to a manufacturer, whereas many chinese multimeters have none. Appliances, "electrical devices", light bulbs have lots of room for HV spacings. Small handheld multimeters have no room for reasonable clearances and sized fuses. They are used generally close to your face and hands with exposed wires.
The issue is cheap chinese multimeters with fake/spoofed safety claims and zero evidence of any testing.
They need to stop this horseshit. It just fuels threads like this spinning around the requirements amidst unknown capabilities of the product. Because they can and do involve measurements needing some trust of the numbers- yet they command zero trust for safety, having no evidence of testing or any formal vouching.
We know SFA about the DT830's abilities or design, and there are dozens of variants.
A simple question about suitability for measuring 240VAC mains is a guessing game. People soon will be using these on electric cars and she'll be right.