Clothes dryer fault

[Eric Oppel]

I have a clothes dryer with the older style loop shaped element which has developed the very common fault where it trips the standard household 30mA earth leakage circuit breaker on the house (or safety switch as it is sometimes known here in Australia) whenever the heater element starts to warm up. I can run the dryer on the cool (fan only) cycle with no problems. Obviously some sort of slight leakage to earth is going on here from the element itself? Can anyone please tell me what causes this to happen? Can someone who has repaired such things please tell me if replacing the heater element fix the problem or is there something else going on which causes it?

 

[davenn]

Hi there
welcome to EP

I have a clothes dryer with the older style loop shaped element

Make and model would be helpful

have you googled for the fault and cause, as you said it's a common fault, so surely it has been documented ?


Dave

 

[Eric Oppel]

HI Dave and thanks for the welcome.

I did already do a bit of a Google search but all I've found so far is fairly general advice from people who don't have electrical/electronics knowledge and of course they say things like get a technician in to fix it etc. hahaha
That's why I thought I'd try here where people know what they are doing as they have some knowledge and experience.

The dryer is a Simpson "Maxidry 457" which is very common here in Australia. It's very similar to the ones sold under the Hoover brand and I believe they are all made by the same company.
Most dryers sold in Australia regardless of the brand or model seem to get this problem eventually as they age.

Apart from the drum drive belts breaking as they age, this fault is the main reason people in Australia throw out and replace their dryers and it seems such a waste, when replacing the element may be all that is required to fix the problem. Most of these machines don't even have a pcb, but just a simple timer, element and motor arrangement.

I'm all for repairing and reusing things rather than throwing things out and constantly buying new things as our consumerist society would have us do.

 

[Bluejets]

Sounds like an old Simpson dryer.
These elements consist of a heater element wire encased in manganese dioxide powder inside a metal sheath.
Construction is similar to pyrotanex cable and the purpose is the same, to withstand high temperatures.

The problem of tripping the safety switch stems from the fact that a small amount of moisture has been sucked into the manganese dioxide powder which is usually sealed with a silicon end seal or a dab of silicone.

The fix is ....easy one, (well, used to be) find someone with a power circuit not protected by an elcb and allow the element to heat right up.

or 2. dismantle the element from the machine and , starting mid-point with a propane torch, warm up the sheath in each direction towards the ends in an attempt to force out any moisture. Usually requires the use of a megger to know whether you have succeeded or not and the element needs to cool before testing. Once a good test is established, seal the ends once again with silicone. (silastic)

Note that some households still operate under the old wiring rules where the refrigerator outlet in the house was not on a safety switch.

Edit:- Similar fault exists in anything with a similar heater element structure such as steam irons, frypans etc.

 

[Eric Oppel]

The dryer is a very common Simpson "Maxidry 457" which is similar to the even more common Hoover brand dryers. These are the two most common dryers in Australia by far.

As far as I know most Australian dryers get the same fault as they age.

 

[Eric Oppel]

Sounds like an old Simpson dryer.
These elements consist of a heater element wire encased in manganese dioxide powder inside a metal sheath.
Construction is similar to pyrotanex cable and the purpose is the same, to withstand high temperatures.

The problem of tripping the safety switch stems from the fact that a small amount of moisture has been sucked into the manganese dioxide powder which is usually sealed with a silicon end seal or a dab of silicone.

The fix is ....easy one, (well, used to be) find someone with a power circuit not protected by an elcb and allow the element to heat right up.

or 2. dismantle the element from the machine and , starting mid-point with a propane torch, warm up the sheath in each direction towards the ends in an attempt to force out any moisture. Usually requires the use of a megger to know whether you have succeeded or not and the element needs to cool before testing. Once a good test is established, seal the ends once again with silicone. (silastic)

Note that some households still operate under the old wiring rules where the refrigerator outlet in the house was not on a safety switch.

Edit:- Similar fault exists in anything with a similar heater element structure such as steam irons, frypans etc.

Many thanks for the advice!

How can I tell just by looking if my fridge outlet is not RCD protected? If it's not I could run a extension lead to the dryer (save me having to move it! haha) and dry it out that way perhaps.

The house was built in 2005 as far as I know.

I also have a double GPO in the meter box outside and am wondering could that be unprotected perhaps as my RCDs are mounted in a seperate plastic wall mounted box inside the house?

Now you mention it I also have one of those toaster ovens with twin hotplates on top that does the same thing. Was going to throw it out but maybe I can save that one too! Awesome!!!!!

 

[Tha fios agaibh]

It is important to mention to use extreme caution if hooking up to any circuit that is not rcd protected. The dryer will likely have leakage currents that can be deadly if come in contact with.

 

[Eric Oppel]

It is important to mention to use extreme caution if hooking up to any circuit that is not rcd protected. The dryer will likely have leakage currents that can be deadly if come in contact with.

Thanks. Yes very aware of that.

 

[kellys_eye]

Given that replacement elements are relatively cheap, why take the time, trouble and risk rather than simply replacing it. It's a 5 minute job.

 

[Eric Oppel]

Given that replacement elements are relatively cheap, why take the time, trouble and risk rather than simply replacing it. It's a 5 minute job.

That depends on your location. In country Australia it can be not so cheap especially once you pay the freight cost to have one delivered. Also there's no risk if it's done in a safe manner. Plus dismantling one with a front mounted element is a pain as you have to remove the drum and belt etc and then reassemble it all. Things here are not as they are in Europe unfortunately.

 

[kellys_eye]

Things here are not as they are in Europe unfortunately.

Ah yes, the old 'colonies'..... still 20 years behind the rest of us

 

[FuZZ1L0G1C]

A tried and tested (but also potentially hazardous) hack is to series the element with a high-wattage incandescent light bulb.
Disconnect the earth/ground, so the element is no longer protected, connect a light bulb of say 150W-200W in series.
While heating the element, the bulb's filament serves as a series 'dropper' resistor, so only partial mains voltage warms the element, without overheating it to red hot (if it gets that hot).
Then do the same from element tab to bracket / earth (danger - keep clear!).
This way, if there are any shorts, lamp absorbs the load rather than the outlet / DB.
Our company used this method to dry out calorifier elements. (Water / steam heaters).

 

[Bluejets]

It is important to mention to use extreme caution if hooking up to any circuit that is not rcd protected. The dryer will likely have leakage currents that can be deadly if come in contact with.

Not necessarily the case.
Earthing of the appliances is a common arrangement to divert any leakage.
It is still allowable by SAA to have existing installations run cooktops and ovens by this arrangement.
Power circuits were the first to changeover to elcb on existing installations followed by lighting ,the latter if any work carried out on the lighting system.

 

[Bluejets]

Given that replacement elements are relatively cheap, why take the time, trouble and risk rather than simply replacing it. It's a 5 minute job.

New elements have been known to have the same characteristic insulation resistance purely due to the nature of construction. Pryotanex can be the same straight out of the box.

 

[Eric Oppel]

Ah yes, the old 'colonies'..... still 20 years behind the rest of us

Yes, and thanks to our crazy right wing government we are heading further and further into the dark ages by the day. All they are interested in is mining fossil fuels. Whilst we have the biggest gas reserves in the world, we currently have a gas shortage as nearly all of it is exported while at the same time they are doing all they can to prevent the country from switching to renewables and having electric cars etc.

We are I think one of the few countries left in the world which doesn't have some sort of incentives to go electric which makes electric cars hideously expensive to buy. Plus very few have been approved for use on our roads anyway.

Then if you want to build your own you have the problem of there being pretty much no manufacturing left in this country so you have to again import all the parts at huge expense. Our postal service in recent years has also become one of the worlds most expensive as they milk it for all it's worth to try to get us to shop in bricks and mortar stores instead of online.

We used to be 20 years behind you but I think it's more like 40 now! What does a common dryer element cost over in Scotland I wonder? Or the postage if you had to have it delivered?

They are also currently building what they call the "National Broadband Network' which uses what they call their "multi technology mix". Basically it means that in city areas they run fibre optic cables to "nodes" at the end of neighbourhoods and then go from the node to your home using the corroded old failing copper wire telephone network. Most people I know who have so far been connected are lucky to get 25Mbps download with a max of 5Mbps up with many getting only around 7-12 down. They call it innovation! I'm currently trying to decide whether I should get two tin cans and a bit of string or maybe invest in a carrier pigeon for faster communications. Apparently the pigeon system works better in the rain?

Was considering using smoke signals but that's risky here in Australia with our summer bushfire problems.
Anyway, I'd better get back to fixing the clothes dryer in my cave now. ;-)

 

[Bluejets]

Many thanks for the advice!

How can I tell just by looking if my fridge outlet is not RCD protected? If it's not I could run a extension lead to the dryer (save me having to move it! haha) and dry it out that way perhaps.

The house was built in 2005 as far as I know.

Could be close to the "changeover" time but if you trip the power circuit safety switch by using the trip that is provided by the manufacturer on each elcb and the frig stays on then you will know.

The reason the frig was initially left off the elcb was, when safety switches first arrived, many would nuisance trip due to the collective nature of the leakage and many installations carried just the one unit. Frig off, people on a couple of days off somewhere, return to a frig full of spoilt food and possibility that a new frig was also required.

It was a common thing to have a neighbor or relative come to check "all was well" in the switchboard when people went away at any time.

These days most circuits are covered by combination circuit breaker/elcb units and in new homes, requirement for all circuits to be connected to same. There are exceptions but the protection of the cabling requirement makes it much more sense economically to fit the elcb.

 

[Eric Oppel]

A tried and tested (but also potentially hazardous) hack is to series the element with a high-wattage incandescent light bulb.
Disconnect the earth/ground, so the element is no longer protected, connect a light bulb of say 150W-200W in series.
While heating the element, the bulb's filament serves as a series 'dropper' resistor, so only partial mains voltage warms the element, without overheating it to red hot (if it gets that hot).
Then do the same from element tab to bracket / earth (danger - keep clear!).
This way, if there are any shorts, lamp absorbs the load rather than the outlet / DB.
Our company used this method to dry out calorifier elements. (Water / steam heaters).

That all sounds fun to do and sounds like it would work too.

 

[Eric Oppel]

Could be close to the "changeover" time but if you trip the power circuit safety switch by using the trip that is provided by the manufacturer on each elcb and the frig stays on then you will know.

The reason the frig was initially left off the elcb was, when safety switches first arrived, many would nuisance trip due to the collective nature of the leakage and many installations carried just the one unit. Frig off, people on a couple of days off somewhere, return to a frig full of spoilt food and possibility that a new frig was also required.

It was a common thing to have a neighbor or relative come to check "all was well" in the switchboard when people went away at any time.

These days most circuits are covered by combination circuit breaker/elcb units and in new homes, requirement for all circuits to be connected to same. There are exceptions but the protection of the cabling requirement makes it much more sense economically to fit the elcb.

Have checked now and you are correct. All my power outlets are protected. I just remembered though I do also have a small petrol generator which I bought to get me through our very frequent power outages here. Might try that!

 

[Bluejets]

Have checked now and you are correct. All my power outlets are protected. I just remembered though I do also have a small petrol generator which I bought to get me through our very frequent power outages here. Might try that!

Sure.....isolated supply.

By "small" I trust you mean more than 2.5Kva. Dryers pull close to 10 amp.

 

[Eric Oppel]

Sure.....isolated supply.

By "small" I trust you mean more than 2.5Kva. Dryers pull close to 10 amp.

Yes, I think it is something around that size but not sure to be honest as I bought it second hand and it has no brand, model or specs marked anywhere on it! Paid $50 for it as it wasn't running when I got it but all it needed was the carby cleaned out and a bit of Aerostart the first time and it runs great now.

Will try it on my leaking 2200W toaster oven first, with only the top (leaky) elements turned on first to see how it goes. Then switch both on and try again. The generator is fitted with a overload cutout so I'll see what happens. Will measure the generator voltage output while I'm at it.
If that goes well I'll try it with the dryer.