sparky Paul wrote:There's a few issues going on here.
Whilst the nominal voltage for the UK dropped from 240V to 230V, it's not quite that simple. The permissible range also changed from 240V +/-6% to 230V +10%/-6%, so you can see that the medial value is still around 235V. In reality, most UK supplies hover around 235-242V, but 253V is permissible, and on rare occasions even this is exceeded. You can see why care is needed when operating near to the limits.
My domestic mains voltage, measured at 9pm Saturday, was 242V.
All that happened, when we got "Europed", was that the British specification of 240V +/- 6% got changed to 230V +10% / -6%. The change in the upper tolerance to 10% craftily encompassed the UK nominal of 240V. Nothing really changed in practical terms. According to one source on the net, it is changing again this year to 230V +/- 10%. Apparently the European 220-volters are finding it difficult to keep within the low limit (they only have 3.8 Volts to play with).
Someone else on the net, talking about the same subject, sums up the reality quite well:
"...This sounded fine in theory but when the costs of replacing all the supply equipment to deliver 230v was calculated it was decided that it was uneconomic (there being no advantage whatever in changing, other than ‘harmonisation’). However, to avoid accusations of failure to harmonise, they simply fiddled with the legal voltage limits. The law now states 230v +10% -6%, thereby allowing the European 220v system to stay at 220v and UK to stay at 240v, yet both appear to be harmonised!"
What the EN thingy really means is that as long as equipment is designed to work reliably between 216V and 253V (perhaps soon, 209V to 253V) without exceeding its specifications, then it will work reliably throughout Europe, which is what the spec is all about.
Anyway, most of that is immaterial, it is the spec of the element that is important.
sparky Paul wrote:
P2 is right that whilst UK BS1363 plug and socket outlets are rated at 13A, operating on or near 100% load for long periods will reduce the service life of these components. Feel how warm a plug gets after supplying a 13A load for an hour or two.
'Tis true that increased loading reduces life, but to me, 13A rating means 13A. Any de-rating factors should be accounted for in the B.S specification and the fundamental design of the thing. A certain amount of temperature rise would be permissible, but a newish, good-quality plug with untarnished pins and tight fuse clips should be within specification. If heating is excessive then a replacement plug or wall-socket should solve it.
sparky Paul wrote:
As I said earlier, it is physically possible to use immersion heaters from 13A sockets with care, but I still would not advise (or condone) it.
It depends upon how the heater is specified. It is pointless specifying a wattage unless the voltage at which that wattage applies is also stated. Heatrae Sadia specify theirs as 3kW@240V, so theirs at least seem okay. It is no different to people using their 3kW Burco's or old-style 3kW kettle elements in their boilers, or, indeed, my kitchen kettle, which is 3kW @240V.
However, the fact remains that we are using a cylinder immersion heater for something that technically it isn't sold for, even though commercial versions are just the same, but probably sold at commercial prices too. I do not have any particular problem with that in principle, home brewers and home-brew suppliers have been doing the same thing with kettle elements for years; except that kettle elements are meant to be plugged in, whereas immersion heaters apparently are not. The
possible high temperatures within the terminal housing can be dealt with using easily obtainable parts, and is no different to any other type of heater that might be employed for the same application. Indeed, Heatrae state that their heaters have a "cold-zone" like commercial ones do, to prevent the terminal box overheating. In fact, most makes must have a cold zone, otherwise the solder would melt on the terminals, which seems to be apparent in the previous photograph. Nevertheless, the temperature in the terminal housing could be expected to reach 100C, so ordinary cable and connectors are inappropriate.
My biggest concern is that the housing isn't water tight. It would be a trivial matter to seal the housing if it wasn't for the ruddy great cable-entry hole in the cover. A gasket would probably do it; indeed, it looks as if a spare sealing-washer for the thread would fit - if it wasn't for that hole. That housing must be water-tight, or housed in a secondary water-tight container, for the thing to be intrinsically safe. Particularly in the home-brew situation where boil-overs are common.
It would be a great shame if immersion-heater elements cannot be made 100% compatible with home brewing. Not only will the supply of kettle elements dry up, but immersion heaters are, in many ways, superior to kettle elements, apart from being cheaper these days. 3kW is a useful size; the energy is dissipated through a large area of element tubing, which gives much reduced wort darkening (compared modern mini kettle-elements which darken the wort considerably). Heck, they even have a convenient thermopocket or thermowell, into which the high-techs amongst us can stick their PT100's, should they be so inclined.
In truth both have equal significance. Although I think with some heleman(SP?) sleeving there MAY be a way to get there to offer splash proof protection.