Heat source pump dryer tripping the rcd.

[Aaron Tolley]

Hoping someone can help.

Since we plugged in a heat source pump tumble dryer, the rcd trips sporadically. Whether the dryer is on or just plugged into the wall.

We had the dryer replaced to make sure it wasn’t a specific problem with the earth. Have also tested the dryer on other circuits and it still sporadically trips the rcd.

Anyone got ideas on what could be wrong?

Pic of RCD attached.

 

[SPECIAL LOCATION]

How does having the drier replaced make sure it wasn't a specific problem with the earth?

Have you tested the RCD?

Have you tested the wiring on the drier circuit?
Does the dryer circuit also supply other sockets / accessories?
Have you measured if there is any natural leakage with any other appliances on that circuit?

I presume that RCD is supplying multiple circuits....
Have you tested the circuit wiring for all circuits supplied via the RCD?
Have you measured if there is any natural leakage on other circuits that share the RCD?

From what you have said so far you have just replaced the drier and removed the RCD without actually doing any initial electrical tests?

Without more concrete info its just guess work..
But if its just a single RCD multiple MCB arrangement I would be thinking along the lines of cumulative natural leakage problems?

RCBO's would assist with these situations.

 

[Murdoch]

Why have you taken the RCD out of the consumer unit?

 

[UNG]

Trial and error will rarely be successful in resolving the more complex RCD issues and without the proper test equipment or employing the services of an electrician it is doubtful you will get a satisfactory conclusion and identify the sources or sources causing the random tripping

 

[michael8554]

Hi Aaron

I expect that RCD lives in your Consumer Unit, and protects half of the house's circuits.

1. Switch off all the MCBs that the RCD feeds, except for the one that feeds the dryer.

Does it still trip ? See 3.

2. If no trip, switch on the rest of the MCBs one by one, building up to them all on, trying different combinations until you find one that causes the trip.

Then try with everything on that circuit off/unplugged eg for the Kitchen Ring - toaster, kettle, microwave etc.

Again, switch on/replug to find the culprit.


3. Unplug or power off everything else on that circuit.

Does it still trip ?

If so as you've already tried another dryer, there's probably a fault on that circuit.

 

[poni]

Pic of RCD attached

what have you replaced this with?

 

[SPECIAL LOCATION]

Hi Aaron

I expect that RCD lives in your Consumer Unit, and protects half of the house's circuits.

1. Switch off all the MCBs that the RCD feeds, except for the one that feeds the dryer.

Does it still trip ? See 3.

2. If no trip, switch on the rest of the MCBs one by one, building up to them all on, trying different combinations until you find one that causes the trip.

Then try with everything on that circuit off/unplugged eg for the Kitchen Ring - toaster, kettle, microwave etc.

Again, switch on/replug to find the culprit.


3. Unplug or power off everything else on that circuit.

Does it still trip ?

If so as you've already tried another dryer, there's probably a fault on that circuit.

(a) There may not be any fault..??
e.g. four good circuits each with 7ma of natural leakage could create sufficient current to trip a 30ma RCD...
16ma or higher can be enough, and 28ma in many cases is certainly enough!
It could be the new appliance is the straw that broke the camels back?

(b) Unless you are disconnecting all of the common neutral connections for each individual circuit that share a supply from this RCD it is impossible to identity exactly which circuit is causing a trip just by turning MCB's off...

As any one of the live circuits can create an imbalance to earth via another circuit that has its live disconnected (MCB off).. but neutrals still terminated on the common neutral bar inside the CU.

(c) Some proper electrical tests are needed in my opinion.

And as per my previous comment RCBO's are your friend in these situations..
Split-Load and/or Dual-RCD boards create a mine-field of issues when trying to identify the cause(s) intermittent faults.

 

[Chewbacca]

Random tripping is usually a fridge or freezer, but it may be a faulty RCD, or a build up of earth leakage from various appliances, one of which is becoming faulty.

 

[UNG]

2. If no trip, switch on the rest of the MCBs one by one, building up to them all on, trying different combinations until you find one that causes the trip.

Then try with everything on that circuit off/unplugged eg for the Kitchen Ring - toaster, kettle, microwave etc.

Again, switch on/replug to find the culprit.

Doesn't really help if it is a cumulative leakage issue though

 

[michael8554]

Cumulative leakage had already been suggested as a cause, without any suggestions on identifying the culprit.

My suggestion goes some way towards that, if as device is not present it doesn't matter if N is not dissed.

 

[UNG]

Cumulative leakage had already been suggested as a cause, without any suggestions on identifying the culprit.

My suggestion goes some way towards that, if as device is not present it doesn't matter if N is not dissed.

And your suggestion to identify the culprit achieves little or nothing as any one of several appliances could be the one that tips the RCD over the edge

 

[newfutile]

You need an earth leakage clamp meter and/or ramp test (RCD) Residual Current Device meter,anything else is just a guess and rarely works

 

[michael8554]

"And your suggestion to identify the culprit achieves little or nothing as any one of several appliances could be the one that tips the RCD over the edge"

Possibly, but why don't you wait for the results of the tests before nit-picking ?

 

[Chewbacca]

And your suggestion to identify the culprit achieves little or nothing as any one of several appliances could be the one that tips the RCD over the edge

Ok , play nicely now, tis the season of good will to all, except stormtroopers of course

I seriously doubt the op has any form of test gear to do a more effective investigation, in which case it's a valid suggestion to at least minimise the impact of nuisance tripping until they can get an electrician in.

 

[Richard-the-Ninth]

Further to what chewie said, need I remind you that this is the DIY part of the forum, and it is a 99% certainty that those who ask questions have no means of electrical testing at all, which is why they come here and ask for advice.
Also the OP has read the replies, but has as yet declined to respond.

 

[SPECIAL LOCATION]

Further to what chewie said, need I remind you that this is the DIY part of the forum, and it is a 99% certainty that those who ask questions have no means of electrical testing at all, which is why they come here and ask for advice.
Also the OP has read the replies, but has as yet declined to respond.

Unfortunately... IMHO RCD related issues DO require some competence and access to reasonable industry standard test equipment..? Or it can end up as a lot of pi55 in the wind!!!!

 

[Murdoch]

And such threads aren't helped when the OP reviews responses but can't be bothered to add detail or answer questions.

 

[Aaron Tolley]

Thanks for everyone’s help. I’ve tried the dryer in multiple circuits and the rcd still goes pop every 10/20 mins. Sounds like the culprit is the dryer, but it’s strange as it’s the second one we’ve had. I wonder whether the fact that’s it’s a heat source pump affects the load on the circuit?

Apologies for not responding sooner I have 3 jobs and a family!!

Professional help is on its way it’s just a busy time of year.

 

[Murdoch]

Thanks for the update.

Do let us know what happens next

 

[johnb2713]

Thanks for everyone’s help. I’ve tried the dryer in multiple circuits and the rcd still goes pop every 10/20 mins. Sounds like the culprit is the dryer, but it’s strange as it’s the second one we’ve had. I wonder whether the fact that’s it’s a heat source pump affects the load on the circuit?

Apologies for not responding sooner I have 3 jobs and a family!!

Professional help is on its way it’s just a busy time of year.

Heatpump Tumble Drier will REDUCE the load compared to a conventional tumble drier. It's mode of operation is the same as a fridge or freezer.