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Clamp meters measure the magnetic field caused by current flowing down a wire. Leakage clamp meters are measuring very small currents and are very sensitive to the point where the earths magnetic field itself can affect your readings. More expensive leakage clamps tend to compensate at least...

I've never seen the round peg type so every day is a school day. I've only seen the oval peg which was an s14s for the twin single-contact caps or s14d for the single oval dual-contact cap in the middle of the fitting. The oval peg lamps are still available in LED variants like Osram LEDInestra...

Are your labels going on the individual wires or over the outer jackets of the cables?

If your target air volume is 30 l/sec you need to look at the manufacturer published fan curve to see what pressure drop is going to equate to the fan delivering that volume. Then you then need to calculate what the static pressure of your proposed duct design will be at 30 l/sec air volume and...

About 10 years ago I had a contract with a mobile network provider to install underground LV electrical supplies and also a local earth for 8 remote transmission towers. The spec was that the earth impedance was sub 1 ohm at the MET which made it one of those tenders where we weren't sure if we...

I had a Dilog earth leakage clamp tester many years ago, it was about a third of the price of the Fluke or Megger and it did the job for about 3 years before it died for no apparent reason.

Not sure about maintenance log requirements, I'm not UK based so I'm not familiar with your local codes of practice. If there's no defrost cycle termination thermostat then setting the time duration of the defrost is trial and error. Just a thought but water can ingress a light fitting by...

I'm assuming it was an RCD tripping? Did you do an insulation test on the light? Did you insulation test any other components such as the defrost elements and the compressor? Even on a hot day the internal temperature of the freezer room will never get even close to zero degrees C, usually...

Removing a meter and a half of pipe won't affect the charge by a significant amount.

Car brake lines use a 'bubble flare' on steel lines which is different to a HVAC 45° flare with an acme threaded brass nut on soft drawn copper lines. Occasionally you'll see 'double flares' used in HVAC as well. As far as torque settings go it's the same debate as it is in the electrical...

Torque settings for HVACR flare nuts is important, it's soft drawn copper pipe so if you overtighten the flare nut cuts into the pipe at the base of the flare which can cause separation and obviously undertightening just means it leaks slowly. It's especially important with newer generation air...

There's no reason LED lamps shouldn't be 'universal voltage' ie 100v-250v and there's no reason they shouldn't have built in surge protection or be designed in such a way as to mitigate surges. There's no reason for lots of things in fact, there's no reason for them to have shyte power factor...

Probably EC motors I'm guessing. It's the way it's going nowadays with electronically commutated motors built into the fan blade hub. All in the name of efficiency but they're basically disposable, you can't separate the motor so even if just a bearing fails the entire fan unit is trash. It's...

Thanks for letting us know. Didn't realise it was a rental, it's good to err on the side of caution and replacing it it sounds like a sensible resolution. Hopefully it wouldn't have cost much more if the electrician was already on site to do the testing.

I'm guessing the main isolater is inside the hand soap dispenser....

I'd agree that a certain amount of sparking would be normal and with it being an isolator switch that's probably only used occasionally I wouldn't worry about it. If for some reason you're using the switch on a daily or regular basis I'd probably just spend the few quid and replace it if it was...

Did your suppliers have any definative answers on why the drive went tits up?

20 years ago power fail regularly damaged VFD's, nowadays nearly all drives are designed to survive a complete unexpected power outage. Usually somewhere in the 600 page, 14 language manual it will state a limit to the frequency of power outages the drive is capable of handing and where I am we...

The frequency gauge will indicate grid overload if it falls below 50Hz for any length of time without correction being applied. This will indicate that supply side demand has outstripped generation capacity and I'd expect they have a plan for this where they'll immediately shed some large...

I've never owned one of those fancy MFT's. I've always been fan of kyoritsu test gear which I think is branded as Kewtech in the UK and I've got several testers I still use regularly in the workshop that are well over 20 years old and still accurate and reliable. Teh clamp/volt meter has...