Motor Nameplate Current vs. NEC Full Load Current Values | National Electrical Code | Lrd12 Overload Relay

Meanwhile in my house (uk) we have a street lamp time switch with a single pole switch that looks like it was designed to handle 30A. It is beautifully engineered from brass that increases the on period as the days get shorter, I felt bad hacking it so that it would turn on my water heater for an hour twice a day, a job it has been doing for 17 years now without incident. Electromechanical is by far the best way for high current loads at any voltage as fatcas I’m concerned.

Back in the day the UK before EU harmonisation the nominal single phase domestic voltage was 240V ac and within a range of +10% and -6% ie 264V and 225.6 V Under EU harmonisation it is 230V +10% and -6% ie 256 V and 216.2 V. I can assure you that voltage control at Primary substations in the UK 33KV/11KV was lowered to the new nominal for the nominal voltage at secondary substations 11KV/415V/230V. A good thing really as it saves energy

I think the issue is more that 8A might be fine for a light but embedding it where another future operator will reasonably assume it is rated at 15A is not fine.

Now we’re getting into more serious stuff. The contactor is a relay that converts the low-voltage signal from the thermostat into a signal to switch on 220V power to the compressor and condenser. When these contactors fail, the A/C unit will go down. They are a cheap and easy to replace. Check the owner’s manual to locate the contactor and replacement model.

The spark-gap Tesla coil itself was

They all have a ceramic rod or coil wrapped with nichrome wire that turn red hot. A vaccum forming table design I looked at used ceramic rods made the same way with reflectors to evenly distribute the heat. I believe all of the above (I did not verify if the table was) were UL marked.

Thanks to the MOVs’ high energy dissipation, they can be used to suppress lightning and other high-energy transients found in ac power-line applications. They’re equipped to withstand large amounts of energy and divert this potentially destructive energy away from sensitive electronics located downstream. MOVs, which are also used in dc circuits, come in a variety of form factors (Fig. 1).

Some adjustment necessary. This shot turned out well at -0.3 EV, but a lot of my shots under bright conditions could really have used -0.7 EV of adjustment.

This is very dangerous. Safety regulations are all about keeping mains voltage away from people, inside casings that are earthed or double-insulated. This has the voltage just lying there. Possibly covered with a bit of silk-screened paint. It’s not guaranteed to kill someone, but for the extra money I’d sooner have a non-deadly heater for a 3D printer.

This causes some headaches for a friend who has to deal with unaware contractors installing 240VAC or 220 VAC devices in condo kitchens what have 208VAC, not 240VAC. Some devices don’t work, some don’t work well.

You don’t need a big contactor to switch 1A at 120v, you can get little “ice cube” relays that switch up to 10A at 120V and they have a plug-in base so easy to change out when they inevitably fail. Most of them, in new perfect condition, make barely any sound. Nothing compared to the noise of fans and stepper motors. The only issue I can see is running AC mains voltage through wiring that is going in parallel with low voltage. Would need to use thick jacketed, shielded cable to prevent too much EMI. Maybe it’d be better suited using a separate transformer just for the heated bed, rectified/regulated but still a higher voltage for better efficiency. Speaking just from my experience as an electrician and hobbyist level electronics/3d printing experience.

I use a variety of a/c and dc fostek ssrs. I have yet to have a problem, but i use them in circuits where 50% of their rated current is the absolute maximum they will ever see.