Switched RCD off before first EHU connection, now permanently tripped

[sidepod]

Pressing the test button classes as a mechanical test on test sheets bit It also tests the tripping mechanism electrically by causing a small current flow imbalance sufficient to trip device.
A full electrical test is obviously better but the simple push test will check its working electrically and mechanically in its basic form.

Yes you’re right but there is a reason a full electrical test is required by the IEE.
Go into your socket on the side of your kitchen unit. Disconnect the earth. Now press the test button. Yup it still works but now you have a van that could kill you.

 

[larrylamb]

Yes you’re right but there is a reason a full electrical test is required by the IEE.
Go into your socket on the side of your kitchen unit. Disconnect the earth. Now press the test button. Yup it still works but now you have a van that could kill you.

The rcd would still operate in that fault with the current leak.
I was talking about a simple test for the rcd which is the test button, not a fault on a socket circuit like you described which will show up on a full test/inspection. How many people pay for an electrician to test their campervan even though they should be tested not less than once every three years or annually if used frequently? Not many mentions of this on any forum.

 

[GrumpyGranddad]

@GrumpyGranddad , never done that....
They say it’s good practice testing the RCD often by pressing the test switch ...also rarely done that doh

one tip : first pull out the plug out of the wall socket and then the plug that goes in to the Cali ...might be running arround with live 220v in your hand from the blue male socket

Haha.
Surely you have a female socket on the end of the cable that plugs into the van?

 

[flying banana]

and about unravelling the whole cable. another load of worry over nothing. at home i have a 30M extension cable used for DIY gardening etc. i bet you all have one too or similar. and i also bet you never ever unravel the whole thing before you use it ! you just unravel enough to reach the hedge trimmers , drill, jet wash etc and off you go. nothing ever happens does it.

 

[The Merle]

RCD/RCBOs need testing quarterly if you can’t remember that then I use to tell my customers to do it atleast twice a year when clocks change.
It’s there to safe your life so test it!

 

[flying banana]

RCD/RCBOs need testing quarterly if you can’t remember that then I use to tell my customers to do it atleast twice a year when clocks change.
It’s there to safe your life so test it!

So is an air bag

 

[The Merle]

So is an air bag

Manufacturer doesn’t tell you to test that, like an RCD but if you want to go for it

 

[sidepod]

The rcd would still operate in that fault with the current leak.

Not with a L-E fault it wouldn’t.

 

[larrylamb]

Not with a L-E fault it wouldn’t.

Rcd/rcbo can work without an earth connection as it's not part of the sensing. So, say no earth at the socket but if someone touched the live wire or a live
metal kettle for example and they were touching something else with a return path it would trip because of the L-N current imbalance at rcd irrelevant of earth connections in the socket. If there is no return path whatsoever then there is no shock risk obviously.
Why do you think it won't trip?

 

[AlanC]

and about unravelling the whole cable. another load of worry over nothing. at home i have a 30M extension cable used for DIY gardening etc. i bet you all have one too or similar. and i also bet you never ever unravel the whole thing before you use it ! you just unravel enough to reach the hedge trimmers , drill, jet wash etc and off you go. nothing ever happens does it.

It depends entirely on the current draw going through the coil of the cable and the size of the cable cores.
I have seen a mains cable reel melted together when a high current was drawn and the reel not fully unwound. Our vacuum cleaner plug gets slightly warm when we vacuum the carpets. So overheating a cable reel is easier than you may think.

Alan

 

[sidepod]

Rcd/rcbo can work without an earth connection as it's not part of the sensing. So, say no earth at the socket but if someone touched the live wire or a live
metal kettle for example and they were touching something else with a return path it would trip because of the L-N current imbalance at rcd irrelevant of earth connections in the socket. If there is no return path whatsoever then there is no shock risk obviously.
Why do you think it won't trip?

I absolutely knew you would say that. The point is that the RCBO should trip by itself when it sees a fault. Without an earth path it can’t. Relying on you to complete the circuit isn’t the point. Presumably you’ve disconnected your brakes because you have an air bag?

 

[larrylamb]

Yup it still works but now you have a van that could kill you.

Not with a L-E fault it wouldn’t.

I absolutely knew you would say that. The point is that the RCBO should trip by itself when it sees a fault. Without an earth path it can’t. Relying on you to complete the circuit isn’t the point.

I was countering the first two statements which are incorrect. You've now just confirmed what i said in a different way. Think we are looking at things differently, it does rely on you to complete the circuit as that is then the rcbo fault condition, so it is absolutely the point. An rcbo can't 'see' a fault until it creates a fault condition. Without the complete circuit it is just a socket fault, there is no fault on the rcbo whatsoever. You haven't explained how the van could kill you?

 

[sidepod]

Let me explain testing of RCDRCBO’s , the electrical way not the Test Button method.



The key here is time. The human body can only withstand current for a small amount of time. (30mA is derived from resistance of human body at 22Kohm/50v Touch)

When an RCD is tested, the equipment measures and records the time taken for the device to trip and clear the fault. As I explained earlier 5 tests are carried out. !/2 load to prove the device wont trip excessively. Load and 5xload. The later 4 are carried out at 0 deg and 180 deg phase angles and, this is the important bit, the trip times are recorded. At 150mA(5x30ma) for example, the threshold is 40ms.

Over the years I’ve tested many and seen them go anywhere from 4/5/6ms all the way up to 30ms. Some fail and take longer than 40ms. This is the part that could kill you. Just because you’ve pushed that test button and seen the unit trip it doesn’t mean it’s tripped quickly enough to keep you alive.

So the next time you use your body as a CPC (you know what a CPC is? Course you do) as you’ve indicated is acceptable, just pray the device on the other end is quick enough.



Back to my original point, pushing that test button, whilst a good thing, isn’t indicative of a safe installation.

 

[The Merle]

Let me explain testing of RCDRCBO’s , the electrical way not the Test Button method.



The key here is time. The human body can only withstand current for a small amount of time. (30mA is derived from resistance of human body at 22Kohm/50v Touch)

When an RCD is tested, the equipment measures and records the time taken for the device to trip and clear the fault. As I explained earlier 5 tests are carried out. !/2 load to prove the device wont trip excessively. Load and 5xload. The later 4 are carried out at 0 deg and 180 deg phase angles and, this is the important bit, the trip times are recorded. At 150mA(5x30ma) for example, the threshold is 40ms.

Over the years I’ve tested many and seen them go anywhere from 4/5/6ms all the way up to 30ms. Some fail and take longer than 40ms. This is the part that could kill you. Just because you’ve pushed that test button and seen the unit trip it doesn’t mean it’s tripped quickly enough to keep you alive.

So the next time you use your body as a CPC (you know what a CPC is? Course you do) as you’ve indicated is acceptable, just pray the device on the other end is quick enough.



Back to my original point, pushing that test button, whilst a good thing, isn’t indicative of a safe installation.

You guys crack me up, I bet he’s fallen asleep reading all this.

the original point is an RCD/RCBO is required by the manufacturer to be tested (by test button), by what they state normally monthly or 3 monthly. That’s coming from NICEIC sparky (me). If you want an RCD test I’ve always got my tester on board.
Happy safe camping

 

[larrylamb]

I'm not asleep. Lol.
I know how rcd's work and how to test them and qualified to do so.
Pod was correct with last statement with regard to a faulty rcd. However the original scenario and assumption was the rcd was working perfectly so would trip in the required time if anyone touched a live wire and there was a L-E fault on the socket, regardless of earth connection, no-one dies.
It's obvious a faulty rcd unit puts lives at risk in a shock situation. Like an mot, an electrical test only proves it was fine on that day.

I think we can all agree they are lifesavers when fitted in a camper, home or industry etc.
Other members are either bored, asleep or hopefully slightly better informed now with our debate.
Happy Camping as they say.