advice on 3.6 kw kiln

[sunshinewelly]

What did the manufacturer's fitted plug look like?

Which country was the supplier in?

it was a german manufacturer and was a standard EU plug - ie 2 prong plug (i did use an adaptor for the plug orignally but that started melting after one firing)

https://www.warm-glass.co.uk/images/pdfs/products/Nabertherm Kiln Operating Manual- F Range.pdf

http://www.nabertherm.com/produkte/details/en/artscrafts_toplader

its a eco 60

 

[JohnD]

i assume i need the kiln hard wired at the other end

If it is a big, heavy, fixed appliance, you can hard wire it.

If it is movable, you can have a plug and socket, of adequate rating, probably a blue one.

I don't understand if you purchased it from a UK supplier, or imported it from another country.

 

[Adam_151]

the manufactuurers of many kilns sugggest not to use an RCD as bisque firing casuses issues with an RCD. a quick look on ceramic forums also confirm the same

Its an old school thing, but there is at least a grain of truth it in it. Most heating elements consist of a coiled resistance wire inside a metallic casing, with the void between packed with magnesium oxide, very similar to micc/pyro cable, and the manufacturer's sometimes refer to them as 'pyro-bar' elements. The problem with MgO is its hydroscopic (readily absorbs moisure from the air) as an element ages, the seals on the end can become defective and moisure can start to enter, now if the element is used often then its kept dry, but for a kiln in a shed that might not be used for a few months, you might come back to it and not be able to switch it on because it keeps tripping the RCD... link out the RCD, run it upto temperature for an hour and the moisure is driven out and it can then be put back how it was and it'll be fine if its not allowed to absorb moisture.

There used to be a school of thought to keep cookers off RCDs for this sort of reason, but now its not really feasable, and it doesn't actually cause too many problems in practice.

Under the current regulations 30mA RCD protection has to be provided for any socket of 32A or less which might reasonable be expected to supply equipment out of doors (thats been a requirement since the early 90s), any socket of 20A or less for general use, and to any cable without mechanical protection which is concealed within a wall at a depth of less than 50mm, and to any circuit which serves points in a bathroom/shower room. As a result generally everything in a standard house goes on RCD these days, al;though it is possible to install in a way which doesn't need it.

Also note that any 'commando' type socket outlet would have to have an interlocked switch mechanism in a domestic environment

 

[flameport]

the general advice though with kilns is not to fit an rcd

If you don't want an RCD, then it is possible.

The kiln would be permanently wired to an isolator switch, and the cable for the circuit from the consumer unit will have to be installed using a method which does not require an RCD.
That also avoids the use of an interlocked 16A socket & plug, which will be far more expensive than a fixed wiring connection.

 

[stillp]

Isn't the problem due to the electronic control causing the current to be pulsating DC, rather than AC? That would need a Type B RCD.
http://www.doepke.co.uk/catalogue/Cat-pdf/rcds.pdf

 

[JohnW2]

Under the current regulations 30mA RCD protection has to be provided for any socket of 32A or less which might reasonable be expected to supply equipment out of doors (thats been a requirement since the early 90s), any socket of 20A or less for general use, and to any cable without mechanical protection which is concealed within a wall at a depth of less than 50mm, and to any circuit which serves points in a bathroom/shower room. As a result generally everything in a standard house goes on RCD these days, al;though it is possible to install in a way which doesn't need it.

Not for much longer, other than by hard-wiring. Assuming it stays 'per draft', the 18th ed. will, from next July, simplify the situation by simply saying that all (new) sockets (up to and including 32A) must be RCD protected.

Kind Regards, John

 

[Adam_151]

I wouldn't assume anything John, I understand there were quite a few comments made regarding that proposed requirement. If you remember back when the 17th edition was a DPC, it was proposed to allow unprotected cabling outside of prescribed zones as long as it was on a 30mA RCD, in prescribed zones we would have been able to carry on as we were before under the 16th. That got flipped completely around by the time it was issued! I am lead to believe that they were acting on studies that suggested if you were going to drill a cable, it ended better if it was on a 30mA and had to incorporate something along those lines into the standard

 

[sunshinewelly]

If it is a big, heavy, fixed appliance, you can hard wire it.

If it is movable, you can have a plug and socket, of adequate rating, probably a blue one.

I don't understand if you purchased it from a UK supplier, or imported it from another country.

Hi purchased from a UK supplier but the item was shipped from Germany to us

 

[sunshinewelly]

Ultimately I want the most cost effective safe solution. I also don't want to be ripped off by an electrician so this thread has been helpful in knowing what to ask for.

 

[winston1]

it was a german manufacturer and was a standard EU plug - ie 2 prong plug (i did use an adaptor for the plug orignally but that started melting after one firing)
O

Not standard. France, Italy, Germany, Denmark, and Switzerland all have different incompatible plugs.
It would seem yours was a German one, known as a Schuko plug. It does have an earth, two side contacts. Most probably your adapter did not provide the earth contacts so would have been dangerous anyway. Schuko plugs are rated at 16 amps and are on 16 amp circuits. But as we know UK plugs are only rated at 13 amps and the U.K. Post Office downgraded them down to 9 amps some years ago (don't know if this still stands).

But all of this shows the danger of using adapters for anything larger than a shaver. The various electrical standards around the world are generally safe in their own right but dangerous if mixed. Even worse most adapters don't conform to any standards.

 

[JohnW2]

I wouldn't assume anything John, I understand there were quite a few comments made regarding that proposed requirement.

There's obviously no certainty, but I'd be surprised if this one doesn't persist. After all, long before the 18th DPC was born, a good few of us were saying that it was "only a matter of time" before RCD protection was required for all sockets.

Anyway, we have not got to wait too long to find out! I also doubt that it will be 'too long' before they start tightening up the 'loopholes' whereby one can (if cable/routing does not itself require RCD protection) evade the need for RCD protection by hard-wiring things that might be expected to be supplied via a plug/socket ... and then, in the longer longer term, maybe RCD protection of everything??

Kind Regards, John

 

[sunshinewelly]

So putting aside future changes if I get an electrician to hard wire the kiln with an isolation switch I don't need a rcd. Is that correct. Again sorry for my ignorance

 

[JohnW2]

So putting aside future changes if I get an electrician to hard wire the kiln with an isolation switch I don't need a rcd. Is that correct. Again sorry for my ignorance

It's a bit more complicated than that. It depends upon what cable the electrician uses and what route the cable takes. If he uses 'ordinary' ('flat twin and earth') cable, if any of that is buried in a wall (less than 50mm deep), then the circuit would require RCD protection. That requirement could be lost by running the buried cable in metal conduit, or by using something like armoured cable. Ordinary cable not buried in walls (on surface, under floorboards etc.) would not create a need for RCD protection.

Kind Regards, John

 

[ban-all-sheds]

it was a german manufacturer and was a standard EU plug - ie 2 prong plug

So you removed a plug rated at 16A and replaced it with one rated at 13A.

 

[winston1]

So you removed a plug rated at 16A and replaced it with one rated at 13A.

Not a problem of course with most items rated below 3Kw, but in this case!