Fridge freezer tripping the 230V trip switch

[laimeduck]

I have a Thetford Norcold N145a Fridge Freezer fitted in my 2005 Benimar Perseo motorhome.

We always use EHU, and very rarely use gas. Whilst driving we switch the fridge to battery which only operates the fridge, and keep a few freezer blocks in the freezer to keep that really cold.

 

For the last few years when we hook up to EHU for the first time in spring and select 230V for the fridge, there is an audible "click" from the fridge and the trip switch in the van and garage are tripped.

This happens each time we try 230V.

 

If I then select gas, then the fridge freezer operates normally.

 

I have found over the years, that if I leave the fridge freezer operating on gas eg overnight, then select 230V the next morning, all is fine and the fridge works again on EHU.

There is obviously a relay or some electronic thingamyjig in the fridge which "sticks" and causes this, but once the fridge is cooled down by gas it sorts itself out?

 

Anyone know what is behind the front panel of the fridge freezer which is causing this? A relay? a PCB fault? Something else?

And is it fixable?

 

As long as I can get the fridge freezer working I'm not that bothered - it is at least 17 years old but if there is a fix, it would save a fair amount of hassle & jiggery pokery! It really only seems to happen at the start of the season, or after a long lay-up.

 

Thanks

 

Jeremy

[Keithl]

Damp?

 

Warming it up with gas dries it out. Try blowing a hair dryer or low power heat gun through the rear vent apertures with grilles removed before switching it on next time and see if that helps.

 

Keith.

[mikefitz]

The protective circuits are preventing possible electric shock and/or circuit overload and possible fire. If you are in a situation where the protection does not operate there could be serious injury or damage. Repairing or replacing the defective fridge would be the preferred course of action.

The most likely is the 230v element rather than the control pcb, parts cost around £35 for heater element and £150 for the pcb.

 

Mike

[laimeduck]

Keithl - 2021-04-25 6:58 PM

 

Damp?

 

Warming it up with gas dries it out. Try blowing a hair dryer or low power heat gun through the rear vent apertures with grilles removed before switching it on next time and see if that helps.

 

Keith.

 

Keith - Thanks for the suggestion, but it is easier for me to simply use the gas. Don't have a hair dryer!

 

Mike - I really don't think it's feasible to remove the fridge freezer which is well and truly shoehorned in, and unless it stops working totally I'm not going to shell out upwards of £1000 to replace it.

 

I have tested it over the last few days by disconnecting the EHU overnight then reconnecting and starting the fridge on 230V and it is once again working as it should.

 

I was really wondering what causes the audible click when it cuts out?

[Brian Kirby]

It would be useful to know what your "main switch" is. I've no idea what might have been fitted to a 2005 Benimar, but would guess it it is probably an RCD (residual current device). I'm assuming that it is only the main switch that trips (i.e. not any of the individual circuit MCBs)?

 

If the above is true, what it is telling you is that at the point you switch on the fridge on mains, there is an earth fault. That is to say that the current flowing through the + side of your main switch into the van's electrical system, is greater than the current flowing out through the - side of your mains switch from the vans' electrical system - meaning that some current has leaked, by some means, to earth. That fault could be anywhere after the fridge switch (which I assume is that on the fridge control panel), but it does indicate current leaking to earth, instead of all flowing back down the - circuit, as it should.

 

You also say this knocks out the trip in the garage. I assume this is in your garage, from which you rig your EHU cable to your van when at home?

 

These are (intentionally) sensitive switches, but that enough current leaks to knock out two RCD type switches suggests to me (not an electrical engineer or an electrician!) that you have a genuine problem that should be investigated and eliminated, rather than just being worked around. Have you tried contacting Thetford, as it may be a known problem? Even if it isn't, they should be able to put you in touch with someone who can test the fridge circuits, within the fridge as well as within the van, to see if there is an identifiable fault.

 

The problem may be in a junction box at the rear of the fridge, in which a wire has loosened with vibration and moved, or has an odd strand of wire that contacts, the earth wire or terminal, or within the fridge circuitry itself.

 

It might also be a good idea to get your EHU cable checked for continuity, but also both plug and socket wiring for tight terminal screws.

 

The click you hear may be no more than the sound of the Trip/s triggering as it/they register/s the leakage current. But, if you're using EHU when on site you will have 230V AC into your van, and until the fault on the fridge is identified and resolved it should not, IMO, be assumed that the electrics generally are otherwise safe.

[laimeduck]

Brian Kirby - 2021-04-26 6:40 PM

 

It would be useful to know what your "main switch" is. I've no idea what might have been fitted to a 2005 Benimar, but would guess it it is probably an RCD (residual current device). I'm assuming that it is only the main switch that trips (i.e. not any of the individual circuit MCBs)?

Brian

As always thanks for your considered reply.

In answer to your questions:-

 

The Benimar control panel is the same as in this MMM article from 2005, Page 8

https://tinyurl.com/2aebzswe

The switch that trips is the one on the far RHS.

 

There is no "Main" 230V switch, when the EHU is connected by plugging in the cable, then we get 230V supply in the van.

 

The pictogram of the fridge control panel shows:-

The fridge is turned on using switch "A" on the fridge control panel.

Switch B allows me to select "auto" battery, gas or 230V

(Auto selects the best source)

 

You are correct that the EHU cable is plugged into a 13A socket in the house garage

 

The tripping of the switches is random, sometimes just the van one, sometimes the garage/house one.

(trouble is I can't replicate this now, as once the fridge has been operated for a time - the fault no longer occurs!)

 

I will check the EHU cables and plugs, but I don't think they are faulty? Why would the problem go after the fridge has been operated on gas?

 

When it does happen there is a definite click from the fridge control panel, not just the Benimar control panel.

In normal operation, when the fridge is turned on ( to whichever of the 3 sources) there is also an audible click as the fridge selects which source to use.

 

As I said, the problem has now gone, but will recur after a long layup at the start of the season.

 

Electrickery!

 

Jeremy

[onecal]

Hi

As Keith has pointed out , dampness/condensation can play it's part when not been used, Sometimes the buttons feel just a little sticky and slow to respond , This can be a sign of dampness also dampness can also in the rear of the fridge on connections Are you using winter covers ?

Keep us posted

Hope you are keep well

Regards

[Ocsid]

Trace moisture in the ceramic infill within heating elements, is a known issue for tripping RCDs, with domestic cooker elements.

 

The mains heater in the fridge could be a candidate for the issue here.

[Brian Kirby]

John's (Ocsid) suggestion sounds at least feasible. I'd never have thought that a possibility, but a little web searching shows it to be a quite well-known phenomenon. Jeremy's comment that running the fridge on gas first cures the problem also points the same way. Brendan asks about winter covers. If not fitted they may help.

 

But, if I remember Jeremy lives somewhere on the Marsh? That being the case, and the Marsh being a misty, moisty, sort of a place, I wonder if winter covers would make that much difference. Besides, the covers would never keep the Marsh fairies out, and they're as like to be the problem as any normal moisture. So I reckon that's it Jeremy, the Marsh fairies have got into your heater insulation, and they won't come out until you turn on the gas to make them warm. Once they're away, the fridge should be fine! :-D

 

More seriously, it may be an ageing problem, giving early warning that the 230V element is beginning to fail. The insulant in the heating element has to be a good electrical insulant, but a also very good conductor of heat, so possibly, over time, it becomes more moisture permeable. It seems the best remedy is to heat the element from an alternative heat source before trying it on electricity. But, as a precaution, unless you have a multi-meter yourself, it may be worth getting the 230V electrics checked with particular reference to live to earth, but also neutral to earth, resistances.

 

I think your "main switch" is probably the one that shows top right of the control panel in the Perseo review, which seems to have a black blob above the switch toggle that looks as though it may be the RCD (RCBO?) test button. The other breaker is presumably for the lower amperage circuits. Unless, of course, there is another board somewhere with a bunch of ELCBs on it.

[laimeduck]

Brian Kirby - 2021-04-27 6:29 PM

 

John's (Ocsid) suggestion sounds at least feasible. I'd never have thought that a possibility, but a little web searching shows it to be a quite well-known phenomenon. Jeremy's comment that running the fridge on gas first cures the problem also points the same way. Brendan asks about winter covers. If not fitted they may help.

 

But, if I remember Jeremy lives somewhere on the Marsh?

Brian and Brendan, (Onecal) and & John (Oscid)

 

Yes Brian I am a Marshian!

 

The theory that damp is the cause, is my favourite, and I will endeavour to warm up the fridge after a lay up using the gas. I'll also have a look at making some winter covers for her vents. ( What size mesh will stop the fairies getting in?)

 

I also agree that age will be a factor, dear old Mabel is now getting to be an old lady - at least 16, and maybe 18 years old for the base vehicle.

I hope there will be a few more years life in her yet, she does everything we want of her and I doubt in the current climate that we will replace her.

 

I've just had a look at access to the fridge workings and as the pictures show, there is no access at all inside. Would I get access to the element through the lower vent outside should I need to replace the element?

 

And finally Brian - thanks for pointing out the test button on the Benimar control panel ... I never knew that was there!

 

Although the general perception of Romney Marsh is that of a damp dank place full of Owlers and scarecrows galloping off into the mist on a mysterious dark stallion on a blustery stormy night, the reality is markedly different.

We rarely get mists or fogs, and the weather generally skirts us on the old Saxon shoreline to the north running through Rye to Hamstreet to Bilsington, Aldington and Lympne.

 

While the rest of Kent (and often Brian, your neck of the woods in Sussex), is wet, we Marshians are in sunshine and dry! The very occasional fret is all we seem to get?

 

However we do find that the Marshian fairies are somewhat capricious and mischievous so could be involved in tripping the fridge if we don't keep them warm!

[Brian Kirby]

Jeremy, I don't think any vent or vent cover made by man could keep Marsh fairies out. They are, after all, not just any fairies, but Marsh fairies. I think you have to get the vent covers made by the fairies themselves. Perhaps, if you had a word in the right ear.......................but being a Marshian, you'll know who!! :-D

 

Superficially, if you have a close look at the actual vents you will find the word Dometic, or even Electrolux, somewhere on them, as they look very familiar. Our Hymer had a Thetford fridge, but the external vents were Dometic.

 

If so, all you'll need is two Dometic lower vent (the upper vent has provision for a gas flue that your van doesn't have) winter covers. The vents on your van are both identical, and are so close to the Dometic/Electrolux design visually it is difficult they are not of that make.

 

The covers still allow some air movement at the rear of the fridge, as they incorporate a single vent, to allow the fridge to be operated with the vents fitted in very cold weather.

 

If I'm right the Dometic code for the lower vent is WA130. Your problem is likely to be getting 2 lower vents only, as they seem mainly to be sold in pairs (1 x WA130 + 1 x WA120) but there are some outlets (Ebay) selling them singly. But, being pits of Dometic plastic they are a silly price in the region of £25 each!

 

But, you never know. Possibly a call to John's Cross at Robertsbridge or Caravan Tech at Hurst Green might be worthwhile? There doesn't seem to be much choice in accessory shops near you, or even nearer to Ashford.

[Derek Uzzell]

Jeremy’s fridge is a Thetford model and - looking at Jeremy’s photos - I’m pretty sure the external ventilation grilles are also Thetford products.

 

Thetford vent covers are described here

 

https://www.thetford-europe.com/gb/products/accessories/accessories-thetford-refrigerators/vent-covers

 

though the ‘winter covers’ for my Rapido’s Theftord fridge/freezer are just flat pieces of white plastic that fit behind the grilles.

 

http://www.swordcrowncaravans.com/index.php?route=product/product&path=113&product_id=427

 

Assuming that Benimar weren’t being too bloody-minded back in 2005, the ventilation grilles will have been positioned to allow sufficient access to the top and bottom of the fridge/freezer’s rear for cleaning the gas-burner assembly and (if one is lucky) sweeping the gas flue. I’m very doubtful that one could replace a 230V heating element while the appliance remained in situ.

[Brian Kirby]

Yes, I see what you mean. I think the winter cover you picked out is probably for a "squarer" grill than those on Jeremy's van. For what looks to me a grill of more elongated proportions in Jeremy's case, I think the cover would probably be one of either 40J, 40P, 40R, or 40S, but determining which winter cover goes with which of the various available grills might be fun! Good find that firm!

[laimeduck]

Just a post to update the situation. 2 items on this post.

 

1) I am still able to operate the fridge freezer on 230/240V now without tripping the switches. This seems to concur with the element becoming damp over winter. Dried out on gas a month ago, now all working fine.

 

2) Thetford Ventilation Grilles and winter covers.

The grilles, as Derek suggested, are Thetford, 2 simple slide catches and they come off easily. There is a custom made fly screen mesh behind the grilles. It will be a simple matter to replace this mesh with a home made solid cover for the winter out of correx currugated plastic sheet, which I have. A pair of scissors and job done!

 

Jeremy

 

 

[Brian Kirby]

Just a further thought, Jeremy, but is your van usually parked with the fridge ventilation grills facing the prevailing wind (do we still have one??). If so, would it be practical to change its orientation so that the the fridge is on the lee side? Might help.

[laimeduck]

Brian Kirby - 2021-05-28 7:46 AM

 

Just a further thought, Jeremy, but is your van usually parked with the fridge ventilation grills facing the prevailing wind (do we still have one??). If so, would it be practical to change its orientation so that the the fridge is on the lee side? Might help.

Brian thanks.

 

The van is actually parked facing NW with the grilles on the offside facing NE. The prevailing wind is SW. The offside (NE) is always much more prone to algae than the other sides, presumably because the wind rolls around that side of the van like a slipstream and is therefore more still than on the windy side.

 

(Same effect as sheep lying along a wire fence on the leeward side! They ain't stupid these Romney Marsh sheep!)

 

I guess in a humid atmosphere, the humidity is therefore greater or more concentrated on the leeward which is why there is more algae?

 

Luckily I can park to any compass point so I might experiment next winter.

 

Jeremy