Premier Kettle

[CamdenP]

Hi all,

I'm new to this forum and fairly new to tinkering with vintage electrical items so I'd really appreciate your help!

Power supply isn't my area of expertise but I've done a bit of online research and wondering if I can get away with using resistors to reduce the voltage for my purpose.
I have acquired an electric kettle from circa the 1930s, the voltage is rated 200-220V. UK mains voltage is nominally 230 but I just measured and I'm getting about 248 at the moment. I'd probably be happy to give it a go if it was about 10V above the rating but I feel 30V is pushing it a bit. I don't want to destroy a kettle that has somehow survived for about 85 years. Can I use resistors to reduce the voltage or is this not advisable? If I were to get a transformer, what is the simplest one I can use and where can I get one?

Before anyone gets too alarmed, I have already tested the kettle and it isn't there is no leakage from the circuit to the body of the kettle. The kettle didn't come with a flex, so I have made one from an old extension cord and some bullet connectors that I found in halfords. I have added an earth which I'm pretty sure was never an original feature. Oh and I put a 5 amp fuse in the plug as it draws 3.1 amps.
Oh and the resistance across the heating elements is 62 Ohms combined.

I posted this on a forum called allaboutcircuits.com and was met with a barrage of "Don't do it" and "polish it and put it on a shelf" so I'd REALLY appreciate actual advice. I am fully aware that this kettle is a bit of a death trap, but I'd just like to see if it works, I'm unlikely to use it on a daily basis as it doesn't have any sort of thermal shut off device, originally no earth, made entirely of copper etc and I'll deffo switch it off and on at the wall when testing just in case.
I have also read the "Warning and Disclaimer" section of the forum rules and accept my fate

To sum up:

1. Will I ruin it if I plug it into the mains without any step down?
(My gut feeling is yes)

2. Resistor or transformer?

3. Can you recommend a place to get the required components?

[paulsherwin]

The advice from allaboutcircuits was spot on. What you are doing is extremely dangerous, especially as you don't have obvious expertise in this area.

Even if you somehow hook up the element to the mains without killing yourself or burning down your house, the leakage current between the element and the kettle body is likely to trip the RCD breaker in a modern installation.

[Ambientnoise]

I def do not recommend plugging it in! The power is proportional to voltage squared so very roughly a 25% overvoltage will give 50% excess power.
A resistor would have to take around 4A and drop say 40v, so 160 Watts. This would need a serious component with a large heat sink and suitably constructed for safety etc.
A transformer is the way to go. You would need one with a mains primary and a say 30v 4A secondary and connect it to reduce the applied mains to around 220v. Earlier threads will show how to do this. Such a transformer would cost £10s new but you might pick up a used one. Safety in connection, fusing, cabinet etc is imperative. A brute force voltage reducing transformer would work of course but would be much larger and more expensive to buy.
If you are unsure the pse ask here, mains is lethal you must know what you are doing. If all this sounds ott or goes over your head, please please just polish it and enjoy as an ornament.

[paulsherwin]

The element will get hot if you put voltage across it, but what's the point if you don't intend to use it as a kettle?

[CamdenP]

This item is deffo not safe for everyday use but is deffo worth restoring as a conversation piece.
There is no leakage current between the element and the kettle body, I have already tested that I'm just not au fait with stepping down power and was wondering if there was any alternative to spending 100s of pounds on a transformer, I've seen suggestions on some threads that a dimmer switch may be usable for this application but I'm a bit dubious about that.
I'm not worried about tripping an RCD and seriously doubt that the house will burn down but was planning to test it in the garden as the legs are brass and likely to scorch any surface it's on. If the switch it off and on at the wall, there isn't really any risk of me getting electrocuted. Thanks for the advice!

[The Philpott]

Adding to what has been said, a couple of additionals:

Further to what Paul has said, there is likely to be electrical leakage between the external elements and the kettle body, as the insulation sandwich cannot be trusted at this late stage. This makes it inherently dubious and it's insulating properties could change swiftly if any water weeps into it. (Incidentally I am just wondering if it could be asbestos based, or include a layer of asbestos based composite-which is less than ideal.)

The first thing i would do with this kettle is fill it with water, leave it overnight in the shed and see if some has leaked out- this could make your decision on how to (or how not to) proceed much easier. Adding a bit of blue food colouring and putting some newspaper underneath will make any weeps more obvious. I am not saying this to be offensive but the limit for this appliance may be a role as a retro watering can for the indoor plants or as an ornament. It's certainly a nice looking object.

Dave

[IanBland]

Contrary to the prevailing view, I would give it a go. I wouldn't hug it when I switch it on, but other than that so long as you're not leaving this unattended there is little danger. Of course, there is no guarantee that trying it won't cause something of this age to fail, even on its nominal voltage.

So, it's designed to draw less than 1kW (don't expect a quick cup of tea then), the element is heatsinked by the water, and as it heats up the resistance will rise so the power difference won't be the simple power law anyway.

I'd personally want to use it on a circuit not protected by RCD (annoyingly difficult in modern installations) as it may be a bit leaky electrically. If not physically. Or you could power it up without an Earth and see if you get any significant voltage on the casing.

So long as you're not touching it when testing it, there's no appreciable danger. If something shorts out you'll get a little fart as it takes out the breaker. It's not going to explode or anything.

So; extension lead, power socket some feet away for switch on, fingers in ears and see what happens.

[Paul_RK]

Looks pretty similar internally to two Premier kettles I have here, both of which I've had running, indeed one of them took over household duties for a fortnight or so when nothing else was to hand. Insulation on mine is partly mica and partly asbestos, but the asbestos doesn't look to be flaking at all and seems well contained within the base. One difference is that my two kettles both use a later form of connector, with two pins within a common sheath and a sprung earth contact to the sheath. Neither has ever troubled the household RCD, I wish I could say the same of our 1960-ish cooker.

I very much doubt the kettle would pop during the first minutes of being used on a higher voltage supply, but even so a transformer would be a better option to avoid its having a short but merry future.

Paul

[G6Tanuki]

Powering it up "without an earth" is the sort of suggestion which is likely to attratct swarms of lawyers should anything go wrong!

If you want to power it up do so through an isolating transformer; that way if things fail you're not going to end up directly connected to a few Gigawatts of Messrs Sizewell, Drax and friends.

[Ambientnoise]

Re post #5, a transformer (whether voltage reducing or isolating) is not going to be £100s. Tens of pounds, bought new was my guess for the 30v one.

Some very good points made in all the above.

Ken

[IanBland]

G6Tanuki-

Lawyers? Any electrical work is potentially dangerous if you touch the live bits, but very basic precautions will prevent this danger; those precautions being not touching the thing in question. Anyone not competent to do (or rather not do) this isn't fit to be doing anything experimental at all.

I would be genuinely amazed if anybody can get gigawatts of anything down domestic sized cables, let alone through the fuses. If genuinely concerned the OP could call their electricity supplier to warn them that they may momentarily be drawing a number of amperes.

Also, the kettle could be placed on plastic mat, with a layer of thin cardboard on top of it, and then he could declare it "double insulated".

[Refugee]

I was wondering if a couple of 4.7 ohm metal clad resistors would fit under the base so that they are pushed against the bottom by the base plate.
The heat would then be used as opposed to being wasted. A spot of heat sink paste would be needed between them and the bottom.

[Herald1360]

If it doesn't leak water, half fill it, connect it up with an earth to an RCD protected supply, stand away, switch it on and treat it as if it werelive. If it's electrically leaky, it'll take out the RCD with no drama and you'll know the score. If it doesn't trip off, it'll boil the water eventually. If it works, you can decide whether to invest in a bucking transformer (a 24V 5A one will do nicely and is readily available) and use it carefully or just to polish it nicely and use it as an ornament, with the knowledge that it could be used if you wanted to!

The insulating materials on the heaters (asbestos and mica) don't degrade with age although asbestos has its own problems if disturbed. It might be worth checking out what the feedthrough insulators on the power connections are made from and examining them for any signs of heat damage.

[Techman]

It's often said on here that there's no such thing as a silly question and that no one should be afraid to ask any question - which is true, and quite right. On the other hand it's also said that under certain circumstances that if you have to ask the question, then perhaps you shouldn't be doing, or contemplating doing what you're doing.

Having said all that, I note that a five amp fuse has been fitted and also an earth has been connected. Obviously connecting something like that to the mains breaches a lot of health and safety rules/advice, and if you did something like that in the work place, then you'd be in a lot of trouble.

None of us can advise you to do what you're contemplating, but if you do intend to connect it up to the mains, then make sure that no children etc. are around when you do it. Connecting this kettle up with a fuse and an earth is probably no more dangerous than most members do on here when working on an old radio or TV etc. Some members use isolating transformers and other safety devices to minimise risk. Many members will be a LOT more experienced than you are likely to be, so can do this sort of thing without the likelihood of any accidents.

So you know what to do, but I think the elements rated at basically 200 volts are at risk of going open circuit on the near 250 volt mains that most of us have these days.

I've also got a Premier kettle that I've had for quite a while now and never powered up - until tonight! Mine is perhaps slightly younger than yours and used to have some sort of 'cut-off' device which has been removed and bypassed. Mine is 220/230 volts at 4.4 amps. However, the elements measure just over 100 ohms, whereas they should work out at around 50 ohms, so there's an element down, probably due to it spending its last years of use on 240 volt mains. Anyway, after doing a few checks and tests and fitting a 5 amp fuse in the vintage plug, I put some water in it and plugged it in. Being on only one element it took a bit of a while to boil, but it did and I used the hot water to wash up some bits and pieces in the sink - the last photo below was of it actually boiling, but the camera didn't pick up the steam, note that I only ever got round to polishing the lid, now I need to get on and do the rest:-

[Techman]

As an additional note, I notice that your kettle looks like it has the elements in series, whereas my kettle has them in parallel, which means that if one of yours fails, then the whole lot will be open circuit.

I have got another kettle (not a Premier) that is older and rated at 200/210 volts and has three elements in parallel, if I remember rightly, and one of them was open circuit when tested with a meter, but that one has never been powered up by me - yet!

That kettle of yours with just the two sockets, no facility for an earth and rated for around 200 volts will likely have been for use on the old DC mains supplies of years ago.

It's certainly a very nice kettle that you've got there and I'm very jealous of it!

[The Philpott]

Further to post #13, a check with a 500volt Megger would be advisable here- I notice it's not specified how the electrical leakage test was carried out, it could just have been done at a few volts. The insulating rings for those Frankenstein style feed terminals on the base are probably made of very durable material, but it's not inconceivable that corrosion could have expanded and cracked them.

[Brigham]

It would be useful to find the right mains connectors for it. They are porcelain cylinders holding a simple brass tube type socket.
They are usually red and black, which suggests the DC era.
They are NOT designed to be handled when connected to the supply.

[Techman]

The series bucking transformer that Chris mentions in post 13 would be the way to go. It would have to be properly housed in an insulated, but ventilated case for permanent use. However, none of this conforms to any sort of regulations and if you do something like this, then you do it at your own risk.

If you plug it in with a 5 amp fuse in the plug as you've fitted and a securely connected earth, then the worse that can happen if there's any earth leakage is that either the fuse will blow or your house trip (if you have one) will trip.

[dglcomp]

Would there be any extra advantage in plugging it in via a plug top RCD commonly known as a power breaker, primarily as they seem to ave a lower trip/fault current and as such would trip sooner than a RCD/RCBO in a distribution board, plus it gives you the benefit of RCD protection even if there isn't one in the distribution board.

As for electrical leakage, if done using a PAT style machine that would be done at a few hundred volts even on a battery powered machine. The Fluke 6200 I used to use tests at 500V and the battery powered Seward Prime Test (that I jokingly refer to as my first PAT) I use now also uses 500V for the insulation test.

[McMurdo]

Worth saying that any heating appliance may well test fine when cold but develop electrical leakage when it's hot. One of my old day jobs involved fixing industrial flat irons and many times they'd run for half an hour and then take the RCD out, requiring a new element.