Iron trips RCD!

LostInLM

Plugging the iron into one particular socket in the living room always trips the RCD. It never happens for any others sockets in kitchen etc.

Circuit already has some christmas tree lights/TV/DVD/Sat box/phone and broadband router plugged in at the time.

Any idea what may cause this?

Dardania

Polarity of that socket is backwards?

Reason I say that, maybe the iron has some circuit to ensure that it is earthed (seen a hair tongs thing the girlfriend has that does the same - won't work unless earthed...)

and how this problem hasn't presented itself sooner is none fo the other devices on the socket care

actually second option, seeing as you did say RCD, and not ELCB - maybe you're going over current on that circuit?

user1842

LostInLM wrote: »

Plugging the iron into one particular socket in the living room always trips the RCD. It never happens for any others sockets in kitchen etc.

Circuit already has some christmas tree lights/TV/DVD/Sat box/phone and broadband router plugged in at the time.

Any idea what may cause this?

Is it tripping the RCD or the circuit breaker (MCB)?

Big difference between the two.

user1842

Dardania wrote: »

Polarity of that socket is backwards?

Reason I say that, maybe the iron has some circuit to ensure that it is earthed (seen a hair tongs thing the girlfriend has that does the same - won't work unless earthed...)

and how this problem hasn't presented itself sooner is none fo the other devices on the socket care

actually second option, seeing as you did say RCD, and not ELCB - maybe you're going over current on that circuit?

A polarity inversion will not trip an RCD as there is no current imbalance.

The RCD will only trip if there is a leakage to earth or ground. Therefore the Iron is faulty and needs replacing.

The Iron should trip the RCD on every socket in the house.

It makes no sense that it is tripping only on one socket. Two reasons are:

a) It is tripping the circuit breaker (MCB) not the RCD
b) You have a serious problem with faulty wiring in your house.


I would advise getting advice from a qualified electician

LostInLM

user1842 wrote: »

Is it tripping the RCD or the circuit breaker (MCB)?

Big difference between the two.

Rcd for all sockets tripping.
Was thinking could be the iron but only happens on one socket!

maxfresh

LostInLM wrote: »

Rcd for all sockets tripping.
Was thinking could be the iron but only happens on one socket!

Does the rcd trip if anything else is plugged into this socket?

user1842

LostInLM wrote: »

Rcd for all sockets tripping.
Was thinking could be the iron but only happens on one socket!

Just to confirm that its the RCD thats tripping and only on one socket in the living room when the Iron is plugged in?

If that is the case you have a serious problem with the wiring in your house and your Iron is also faulty and needs replacing.

You need to call an electrician as soon a possible.

Reasoning is that the Iron should trip the RCD when plugged into any socket in the house. Because its only tripping on one socket this means you have an earth fault in the house (some sockets are not connected to earth or have a faulty earth). This is extremely dangerous.

To be honest the more reasonable explanation it that the circuit breaker (MCB) is tripping as you have overloaded the socket. As you seem to be sure that its the RCD not MCB, call an electrician ASAP.

There could be another very unlikely possibility of whats going wrong. The socket could be faulty but only when plugging in a device that requires an earth cable. Try plugging in a different electronic appliance that has an earth cable (heater, fridge, different iron) and see if that trips the RCD. If it does then its the socket that's at fault and get an electrician to replace it. Again this is very unlikely, sockets are designed not to malfunction in this way.

Bruthal

user1842 wrote: »

Just to confirm that its the RCD thats tripping and only on one socket in the living room when the Iron is plugged in?

If that is the case you have a serious problem with the wiring in your house and your Iron is also faulty and needs replacing.

You cant say that with certainty. Earth and neutral swapped at the problem socket would be one possible problem that would cause the same thing to happen.

Another is a slight earth fault in the element near or at the neutral end of the element such as from dampness. Plug it into a reverse polarity socket, and it will trip RCD, but might not in a normal one.

The op should plug something else into the same socket to see.

Something like a kettle would be a good test.

Checking for the correct socket connections would be the first place I would be looking at anyway.

user1842

robbie7730 wrote: »

You cant say that with certainty. Earth and neutral swapped at the problem socket would be one possible problem that would cause the same thing to happen.

That should trip the RCD no matter what you plug into the socket, no just an Iron

robbie7730 wrote: »

Another is a slight earth fault in the element near or at the neutral end of the element such as from dampness. Plug it into a reverse polarity socket, and it will trip RCD, but might not in a normal one.

If this fault is leaking to earth this should trip the RCD in all events. If not the RCD should not trip.

robbie7730 wrote: »

The op should plug something else into the same socket to see.

Something like a kettle would be a good test.

Agreed a kettle would be a good test, I forgot about the obvious one.

robbie7730 wrote: »

Checking for the correct socket connections would be the first place I would be looking at anyway.

A polarity reversal will not cause the RCD to trip. A earth swapped with a neutral would trip when you plug anything into the socket.

Bruthal

user1842 wrote: »

That should trip the RCD no matter what you plug into the socket, no just an Iron

Which is why the OP has been asked if anything else has been plugged into the socket. Often people will only use one device in a socket. Earth neutral reversal is unlikely. But every possibility should be considered.

If this fault is leaking to earth this should trip the RCD in all events. If not the RCD should not trip.

No, if less than 30ma is leaking, it wont trip. This can happen with dampness at the neutral end of the element. The impedence through the water to earth is high, and with the potential difference between the neutral end of the element and earth being 0v, almost all the current will return on the neutral.

Reverse polarity, and you now have 230v onto a damp connection, with PD now 230v to earth through the dampness. So that is a possibility.

A polarity reversal will not cause the RCD to trip. A earth swapped with a neutral would trip when you plug anything into the socket.

A reverse polarity certainly can cause this in certain circumstances.

Example.

Moisture connecting neutral to earth is one of them. If the neutral return path is 0.1 ohms (neutral conductor), and the path through the moisture to earth is 100 ohms, and the iron takes 10 amps, only 1000th of the 10 amps will take the moisture path, or 0.01 amps, not enough to trip the RCD.

Reverse polarity, you now have 230v connected to a moisture path of 100 ohms, which will now conduct 2.5 amps.

Bruthal

LostInLM wrote: »

Plugging the iron into one particular socket in the living room always trips the RCD. It never happens for any others sockets in kitchen etc.

Circuit already has some christmas tree lights/TV/DVD/Sat box/phone and broadband router plugged in at the time.

Any idea what may cause this?

The main questions would be

How long has this been happening? Always, or started recently?

Do you use anything else in the same socket?

If this is only happening at this socket, and assuming its not the only socket in the house with proper earthing, then a visual check to see the socket is connected correctly is required. Even if it is correctly connected, a wrong connection is possible at another socket preceding this one on the circuit.

But a check of the affected socket is what my first test would be after trying the kettle in it.

user1842

robbie7730 wrote: »

Which is why the OP has been asked if anything else has been plugged into the socket. Often people will only use one device in a socket. Earth neutral reversal is unlikely. But every possibility should be considered.


No, if less than 30ma is leaking, it wont trip. This can happen with dampness at the neutral end of the element. The impedence through the water to earth is high, and with the potential difference between the neutral end of the element and earth being 0v, almost all the current will return on the neutral.

Reverse polarity, and you now have 230v onto a damp connection, with PD now 230v to earth through the dampness. So that is a possibility.


A reverse polarity certainly can cause this in certain circumstances.

Example.

Moisture connecting neutral to earth is one of them. If the neutral return path is 0.1 ohms (neutral conductor), and the path through the moisture to earth is 100 ohms, and the iron takes 10 amps, only 1000th of the 10 amps will take the moisture path, or 0.01 amps, not enough to trip the RCD.

Reverse polarity, you now have 230v connected to a moisture path of 100 ohms, which will now conduct 2.5 amps.

Good points so a very slight moisture connection to earth on the neutral side of the element in the iron could cause the RCD to trip only on the incorrectly wired socket (L-N reversal).

Interesting if that is the case should the Iron be replaced as the fault is below RCD tolerances levels on a correctly wire socket.

Bruthal

user1842 wrote: »

Good points so a very slight moisture connection to earth on the neutral side of the element in the iron could cause the RCD to trip only on the incorrectly wired socket (L-N reversal).

Interesting if that is the case should the Iron be replaced as the fault is below RCD tolerances levels on a correctly wire socket.

Well that is just one possibility, your own one about other sockets having bad earthing is also possible. I was just showing how reverse polarity can be a cause.

Even water completely bridging neutral to earth probably wont trip it, as water is a very poor conductor compared to the neutral return path.

It is similar to dardania`s suggestion if there was an earth monitoring setup, reverse polarity can also cause problems.

Really the socket would need to be unscrewed from wall and visually checked as the very first test imo at least. And if looks ok, tested with a meter for polarity in case there is a mistake at a preceding socket.

Thats after a kettle or electric heater is tried in the socket. The OP has not told us if the socket is ever used for anything else, or how long the iron has been tripping it.

If the iron works fine in other sockets, it should be ok to use.

LostInLM

Sorry, never got an opportunity to reply to this over the Christmas.

Since I last replied the iron has given up so I assume this was the primary problem. The socket in question is used for other items (Telephone base, hoover etc.) without any problems. I think it might be coincidence that it just tripped on this socket.

When I get an opportunity I will take a look behind the socket to see that all is ok.