Problem - Fridge Freezer Causing Nuisance Rcd Tripping. How Do I Rectify?

[telectrix]

I have never come across a domestic fridge or freezer where I am which isn't on a standard 3-pin plug and therefore on earth leakage protection.

From what I've read it seems quite common in the UK to run a dedicated circuit specifically for the fridge and use a hard-wired isolator instead of a plug and socket thereby negating the need for earth leakage protection. Why is this necessary? It seems like an expensive option which leaves the user in a far less safe position. If the fridge has a low insulation fault wouldn't it just be better to fix it?? Maybe I'm missing something obvious, if I am please forgive me and go easy

as I see it, it's all down to global warming. fridge/freezers in this country were/are designed to operate at typical UK ambient temperatures. now that global warming has raised our average winter temperature to -2 degrees, they cannot cope and thus get their revenge by leaking to earth in a useless attempt to warm the planet to a temperature whereby they can justify their existence as cooling machines. failing which they just short circuit and take out fuses in spite.

 

[Marvo]

Thanks for the prompt reply Telectrix, makes perfect sense.....but I believe it's know as climate change nowadays, ever since someone asked for actual proof that the planet is getting warmer and they couldn't come up with any ;-)

 

[telectrix]

when the whole of this country is covered in a glacier due to the new ice age. i'll at least be able to say Nah'nah' told you so!!

there is only one significant factor causing climate change. it's 93million miles away.let's see the buggers convert that to energy saving.

 

[Paul.M]

there is only one significant factor causing climate change. it's 93million miles away.let's see the buggers convert that to energy saving.

Can you imagine the SIZE OF THE RCD!

Sure I saw a documentary couple of years ago that said that our planet has a 80,000 year cycle from ice age to as hot has hell. I'll look into that but if it is true? Maybe a debate for another day and thread.

 

[chrisreid186]

'If the fridge has a low insulation fault wouldn't it just be better to fix it?? Maybe I'm missing something obvious'

i agree that would be the best way to go by far , any hint's and tips to finding out where the fault is within the appliance?
anyone know if there any decent books/courses on appliance repair?

 

[KDT Projects]

The client is looking into the warranty but it may come down to me installing a dedicated supply, hopefully then any electrical spikes generated by the fridge freezer won't be caught by the RCD, otherwise i'll take it off the RCD and label it accordingly.

I would PAT test the appliance as i'm qualified in that area but the I don't have a tester.

Thanks for all your swift responses to my query.

 

[Marvo]

........any electrical spikes generated by the fridge freezer won't be caught by the RCD, otherwise i'll take it off the RCD and label it accordingly.

This whole fridge affair is getting more confusing to me. How is the RCD catching spikes? Surely this would be a taylormade job for a surge arrestor or MOV device. How is the fridge generating spikes other than the simple switching on and off of a standard induction motor?

I still don't understand why it's accepted practice to hard wire the fridge on a spur circuit with an isolator rather so you can omit earth leakage protection rather than having the low ins fault localised and repaired.

 

[Merl]

A fairly common problem with some modern frost free fridge freezers is earth leakage on the defrost heaters. If the unit is designed to run off a 13A plug top then there should be no problem with it doing so. Sounds more like a job for a Domestic Appliance Engineer or the manufacturer.


Had the same fault on an American style FF some months back. The manufacturers repaired FOC as it was a common fault on that particular model.

Hope it helps.

 

[telectrix]

I still don't understand why it's accepted practice to hard wire the fridge on a spur circuit with an isolator rather so you can omit earth leakage protection rather than having the low ins fault localised and repaired.[/QUOTE]


i would say that this practice is not to omit earth leakage on the freezer, but to prevent a fault on another part of the installation tripping the RCD and taking out the freezer circuit with it. not nice to come home after a few days away and find a freezer full of soggies

 

[Marvo]

i would say that this practice is not to omit earth leakage on the freezer, but to prevent a fault on another part of the installation tripping the RCD and taking out the freezer circuit with it. not nice to come home after a few days away and find a freezer full of soggies

I agree there's a certain amount of inconvenience if it does trip a RCD but removing it from earth leakage protection is more dangerous for the user so how is this justified?

 

[telectrix]

as long as it's a dedicated labelled socket, it's acceptable if surface wired.relying on the overcurrent device for fault protection. alternatively, the freezer can be wired to a RCD socket or RCD FCU.

 

[pushrod]

The client is looking into the warranty but it may come down to me installing a dedicated supply, hopefully then any electrical spikes generated by the fridge freezer won't be caught by the RCD, otherwise i'll take it off the RCD and label it accordingly.
Thanks for all your swift responses to my query.

You need to know what is going on with the freezer and the other circuits in terms of earth leakage before you just remove the safety feature of a protective rcd! As Des said earlier is it a cumulative fault? Putting fridges on dedicated circuits is not to allow faulty appliances to be used but to prevent nuisance tripping wasting all the frozen peas. If there is a big problem with the fridge you could end up giving people nice tingly feelings.

 

[KDT Projects]

This whole fridge affair is getting more confusing to me. How is the RCD catching spikes? Surely this would be a taylormade job for a surge arrestor or MOV device. How is the fridge generating spikes other than the simple switching on and off of a standard induction motor?

I still don't understand why it's accepted practice to hard wire the fridge on a spur circuit with an isolator rather so you can omit earth leakage protection rather than having the low ins fault localised and repaired.

Of course protecting a circuit with an RCD is more desirable because of the added protection but if nuisance RCD tripping can't be avoided because of the way the appliance operates then another solution must be found.

Since I started this thread iv'e done a little research into the problem and had a look in BS7671.

The clients fridge freezer is quite large and has all the extras and i'm assuming either the defrost function or the ice maker function is causing the problem and also there are alot of other electrical items plugged into this ring circuit and as reg 314.1 states in BS7671, this should be avoided to reduce the possibility of unwanted tripping due to excessive protective conductor currents.

I came across a site that gave me some useful information you might find interesting Marv...

Possible Causes Of RCD Tripping

Faulty appliance – unplug all electrical appliances, does the RCD reset OK? If the RCD resets OK plug the appliances back in one at a time. Reset the RCD as you plug each appliance back in to find the faulty appliance.

Incorrect RCD current rating – RCDs have ‘current ratings’ similar to fuses. The current rating is the current that trips an RCD. The current rating of the RCD could be too low. Seek advice from a qualified electrician.

Poor quality RCD – poor quality RCDs can trip when they shouldn’t. Seek advice from a qualified electrician.

Items with motors or pumps starting – many items with motors or pumps, for instance showers and pond pumps, cause momentary electrical spikes that are big enough to trip RCDs. Seek advice from a qualified electrician.

Older washing machines – aging washing machine heating elements can cause momentary electrical spikes that are big enough to trip RCDs.

Certain wash cycle phases – some cycles of the washing machine, for instance the spin cycle, can cause momentary electrical spikes that are big enough to trip RCDs.

Certain dishwasher cycles – some parts of the dishwasher cycle draw a lot of current, a faulty component, for instance the motor, can trip an RCD.

Overloading a washing machine – too many items in a washing machine can cause certain wash cycles, for instance the spin cycle, to trip an RCD.

Fridges and freezers cooling – the fridge or freezer cooling motor starting.

Turning a sun bed on – a sun bed uses a lot of electrical power, the surge in electrical power can trip an RCD.

Turning an heating element on after a long time of being off – moisture in heating elements can trip an RCD, for instance in a sun bed or electric fire. Try resetting the RCD a few times so that the heating element can cause the moisture to evaporate.

Pond pump faulty – pond pumps sometimes have to ‘work very hard’– for instance when they have ‘digested’ part of a plant from the pond. Check your pond pump for blockages.

Moisture in outside electrical distribution boxes – remove the supply and dry the distribution box. Check the weather seals have not perished.

Moisture in outside electrical sockets – remove the supply and dry the electrical socket. Check the weather seals have not perished.

Ice maker on a fridge – a faulty ice maker on a fridge can cause ‘nuisance’ RCD tripping.

De-frost timer on a fridge or freezer – a faulty defrost element on a fridge or freezer can cause ‘nuisance’ RCD tripping.

Central heating elements – faulty heating elements can cause an RCD to trip when they are turned on by a timer.

Water heating elements – faulty water heating elements can cause nuisance RCD trips when the thermostat tells them to heat the water.

Moisture in wiring – moisture in the electrical wiring is a common cause of RCD trips. Have you just emptied a bath? Taken a shower? Is it raining – rain can get into the electrical wiring under the floors or in the loft.

 

[KDT Projects]

You need to know what is going on with the freezer and the other circuits in terms of earth leakage before you just remove the safety feature of a protective rcd! As Des said earlier is it a cumulative fault? Putting fridges on dedicated circuits is not to allow faulty appliances to be used but to prevent nuisance tripping wasting all the frozen peas. If there is a big problem with the fridge you could end up giving people nice tingly feelings.

Of course getting to the problem of the fault is the main concern which is why iv'e advised the client to look into the warranty. But after doing my research I think alot of these newer model fridge freezers have functions that may cause sensitive RCD's to unfortunatley trip. Another theory I have is there might be too many items plugged into this circuit causing excessive protective conductor currents as stated in BS7671 reg 314.1. Whatever the problem at the least the RCD is doing its job.

 

[KDT Projects]

I am now wondering how these excessive protective conductor currents are being generated but the phenomenon must exist otherwise BS7671 wouldn't refer to it.

Perhaps because the cpc's run next to the line and neutral conductors maybe a small emf would be generated and transfered to the circuit cpc's within the cable runs which the RCD is picking up.

But then if i remember rightly the emf's produced in the line and neutral conductors are supposed to cancel themselves out so maybe thats not the reason or there is is some residual current left and because of the many items connected to the circuit all these currents might add up to a small current that the RCD could detect.

Does anyone have any idea's on how these protective conductor currents are being generated as refered to in BS7671?