RCD's (brought to mined by Dave's tweet) - Page 1
Forum section: electronics / general

author: _Andrew_
author_rank: Regular Contributor
timestamp: January 14, 2017, 02:47:58 am
content: RCD's when they trip are performing out an important function in helping minimize the risk of electrocution and fire but can some times be seen as a nuance if the fault is intermittent and you have one RCD on the supply to all circuits in a distribution panel. So when it trips you loose everything and you are left in the dark.Very commonly appliances that heat water (immersion heaters, kettles, steam irons, washing machines, hobs ect...) are the first to suspected often being that moisture is getting in the electrics or elements breaking down.Followed by exterior power circuits (lights, power sockets ect...) are vulnerable to moisture ingressOther types of heating appliances (ovens, grills, storage heaters ect...)Pet or rodent damage to wiring.Appliance cords getting trapped / snagged.Faulty fixed wiringOther faulty equipment.There is also the possibility that RCD has a fault. There is test equipment for this and an RCD ramp test can be particularly useful in detecting over sensitive RDC'sIn the UK it is now a minimum requirement for new installations that a split load distribution panel is fitted where by there are two 30mA 0ms RCD's in the panel so the properties circuits can be split across the two. Idea being when an RCD trips your not left completely in the dark.The next stage on from a split load panel is to use RCBO's for each individual circuit. There is a higher installation cost (costs of RCBO's are dropping) but has the advantage of only the circuit with the fault present on it trips out. This helps with finding the source as you only have one circuit to check and all the other unaffected circuits carry on as normal.In some circumstances there is another benefit to having individual RCBO's.With the move away from using liner PSU's in devices to switching PSU's with some they can present a higher leakage current. (and also just having too much junk about the place needlessly left plugged in and switched on all the time)So when you start totting up the actual leakage currents of all the devices connected it is possible to start knocking on the door of for instance the tripping point of a 30mA RCD, if there is just one covering the whole installation. Which can be a real pain when you are running about the place in the dark trying to work out what set the RCD off and not finding any faulty equipment or wiring.But in any case if an RCD trips it should always be assumed that there is a fault that has to be found and isolated / fixed.

author: minifloat
author_rank: Contributor
timestamp: January 14, 2017, 03:13:39 am
content: Quote from: _Andrew_ on January 14, 2017, 02:47:58 amHere in Germany new installations must have an RCD device, which is especially necessary for single-phase 16Amp wall outlets.Obviously ceiling outlets for lighting are less prone to be touched, but there it is recommended to also have protection.But AFAIK there is one special regulation about single-phase 16Amp wall outlets, if the load is permanently connected and there is a risk if power is cut, such as fridges etc.

author: Monkeh
author_rank: Super Contributor
timestamp: January 14, 2017, 03:20:57 am
content: Quote from: minifloat on January 14, 2017, 03:13:39 amPretty standard clause, that. Over here you need to ensure the cable is appropriately protected for such circuits (>50mm from a surface, or armoured, or run in earthed conduit).

author: EEVblog
author_rank: Unknown
timestamp: January 14, 2017, 06:46:24 am
content: Quote from: _Andrew_ on January 14, 2017, 02:47:58 amJust changed the one master RCD to 4 separate RCD's (two lights, two power). So now lights won't go out if an appliance fails for trips it when plugged in.Certain plugpacks I had often tripped our existing RCD, the Makerbot and the laptop ones.Our RCD was failing every few hours when we got back from holidays, no problem now it's changed over to separate ones.Source still unknown but the electrician said that old model had a history of unreliability.

author: Monkeh
author_rank: Super Contributor
timestamp: January 14, 2017, 06:47:54 am
content: Some have a tendency to become hypersensitive.Time for a video on leakage currents?

author: EEVblog
author_rank: Unknown
timestamp: January 14, 2017, 06:47:57 am
content: Quote from: minifloat on January 14, 2017, 03:13:39 amThey are compulsory here. And I believe that all new work on switch panels requires the installation of one if not present.

author: digsys
author_rank: Unknown
timestamp: January 14, 2017, 08:44:00 am
content: The rules are slowly favouring individual RCD / current breakers on all circuits, including lights. On some installations, you can either keep ONE light circuit non-RCD,or use battery backed lights at exits, same as the STANDARD in all factories. It's a good thing :-)

author: Towger
author_rank: Super Contributor
timestamp: January 14, 2017, 11:45:50 am
content: What's all this about:I know they can do proper CU upgrades in Oz. Did a registered electrician install these?

author: EEVblog
author_rank: Unknown
timestamp: January 14, 2017, 01:13:44 pm
content: Quote from: Towger on January 14, 2017, 11:45:50 amYes.

author: Towger
author_rank: Super Contributor
timestamp: January 15, 2017, 06:56:38 pm
content: 16A for lighting circuits, he must have checked it is all in at least 1.5mm.Looks like whatever was handy in the back of the van.