| General > General Technical Chat |
| Fused on the 'neutral' side? |
| (1/4) > >> |
| WaveyDipole:
Why are many modern devices now switched fused on the 'live' 'neutral' side? I understand that not every country has a polarised mains system that is grounded on the so-called Neutral side, in which case it probably does not make a difference which side is switched fused, but for those countries that do, doesn't switching fusing on the neutral side render the device potentially dangerous as it leaves the circuit it in a 'live' state even when switched off the fuse has blown? I would like to understand the rationale for such a design? |
| SparkyFX:
In case of a non-polarized plug the switch would disconnect neutral, so the protection might be left to the double insulated casing or connection of the case to protective earth, so it needs two faults to become a safety problem. But the switch is usually considered part of the application, not a protective measure. There are faults, e.g. a broken neutral wire, that can lead to parts of the circuit connected to neutral carry live voltage (through the load) even with polarized mains, so there is not much difference. Applications in which this is not sufficient require a dual pole switch, so both live and neutral are disconnected, or electrical isolation or low voltage. It always depends on what problem the user shall be protected of. |
| Benta:
--- Quote from: WaveyDipole on May 21, 2020, 12:05:37 pm ---Why are many modern devices now switched on the 'live' side? I understand that not every country has a polarised mains system that is grounded on the so-called Neutral side, in which case it probably does not make a difference which side is switched, but for those countries that do, doesn't switching on the neutral side make the device potentially dangerous as it leaves the circuit it in a 'live' state even when switched off? I would like to understand the rationale for such a design? --- End quote --- I'm not certain I understand what you mean. All mains connected equipment that I know of have a double pole power switch for Live and Neutral, the main exception being lamps, where you're supposed to unplug them before changing the bulb. |
| SparkyFX:
--- Quote from: Benta on May 21, 2020, 04:29:46 pm ---I'm not certain I understand what you mean. All mains connected equipment that I know of have a double pole power switch for Live and Neutral, the main exception being lamps, where you're supposed to unplug them before changing the bulb. --- End quote --- Nope. Certainly not the case, not with switchable connection blocks, devices and such. Test it if you want to know for sure. |
| Benta:
--- Quote from: SparkyFX on May 21, 2020, 07:00:35 pm --- --- Quote from: Benta on May 21, 2020, 04:29:46 pm ---I'm not certain I understand what you mean. All mains connected equipment that I know of have a double pole power switch for Live and Neutral, the main exception being lamps, where you're supposed to unplug them before changing the bulb. --- End quote --- Nope. Certainly not the case, not with switchable connection blocks, devices and such. Test it if you want to know for sure. --- End quote --- Please elaborate. What is a "switchable connection block" and what are "devices and such"? Somewhat nebulous... |
| Navigation |
| Message Index |
| Next page |