basic electric supply questions..

[Fil]

so far all my brews have been in a kettle element powered placky boiler.
Ive had my eye on building bigger kit for a while and am about to make the final decisions on elements.

so am i right in thinking that 3kw is the limit for an element plugged into a domestic ring main. and that a ring with a 32a mcb/breaker will support more than one 3kw element but not from the same dbl socket..

im a patio brewer currently and run a couple of extension leads(2.5mm coper wire) from the kitchen sockets to power my current elements.

for my bigger set up with 1 x 3kw element in the hlt and 2 x 3kw in the boiler, which will be in a shed, I plan to run similar extension leads out to feed the power. the extension leads will be about 30-35m long.

is this a viable plan? above the elements there will be small drains on power such as a light radio controller board and pumps, but no more than 1x3 kw element per extention lead, max of 500w? for anything else...

could i support bigger elements? the boiler and hlt volumes are 100l

tia

[darkonnis]

Well, I seem to remember kev was using a single 3kw element in a 100l set up. so no reason why you couldnt do this on 1.
Insulate the boiler and that'd probably make life much easier.

Currently I run 2 fridges and my 3kw element in the garage no dramas and I get a solid boil on an uninsulated 70L set up.
Of course, you shouldn't really exceed the mains maximum but as with all things. If you're careful and accept that you're pushing the limits of what the kits capable of and act accordingly there isn't much of an issue.

In summary, you don't need bigger elements and I don't think you could support them, not via extension lead atleast. 3kW would be enough.

[lord groan]

Make sure the extension leads are definitely 13A rated, There are an awful lot out there now that are only 10A rated, and have thinner conductors. I even spotted some in B&Q before christmas which were in packs printed "10A extension lead" I noticed they definitely had the thinner cable and on the plug it said fitted with 13A fuse! Fire hazard or what?
lg

[vacant]

im a patio brewer currently and run a couple of extension leads(2.5mm coper wire) from the kitchen sockets to power my current elements.

If you have a point for an electric cooker and there's a three-pin socket on that, it should be a separate circuit from the kitchen/downstairs power sockets.

[Fil]

cheers chaps, it would be ideal to run a 32a supply up to there but its about 50m round the perimeter to get there and i have plans for a workshop to sit in between so when that is up i will get a proper power supply hooked up via that.

extension leds that length are far and few between and dont come cheap so its probably a diy cable job.

it seems that 1.5mm flexible cable is rated for 16A,
so would this stuff be suitable for making 2 lengths up with?

http://www.screwfix.com/p/tower-arctic- ... _container

or should i be looking at this stuff in 2.5mm??

http://essentialsupplies.co.uk/acatalog ... tAodeikA4Q

i do not expect to leave the leads plugged in and left for periods longer than the brew takes

now to check out ebay elements again...

[darkonnis]

f its jsut a 3kW element, screwfix sell them too

[themadhippy]

Strange as it may sound we aint supposed to use arctic flex outdoors,and for the length of run at 3kw you realy need to be looking at 2.5mm,so HO7 RN-F,or if you can find it either HO5 RN-F or even HO3 RN-F,the difference is the maximum voltage,3 is still good for upto 300v

[Fil]

right 2.5mm cable for the extension leads and 3kw per lead is gonna work

thanks again. just dawned on me one line can run from the 16a supply to the garage, that will cut 5-6m off a lead length

My focus on elements is on the smaller access hole sort than the big immersion type..and the element choice is clouded by features of the candidate pots, i have 3 candidates fot hlt and kettle but one has bloody thick walls of hi grade SS, another is a long rectangular shape with a large open surface area, and limited clearence at the rear of element mounting point, and the smallest a standard french 98l stock pot has holes cut to the previous owners design, some could be used/enlarged but some will need plugging...

.

[Kev888]

Just to confirm some of the above:

Yes I do run my 100L garage brewery off a supply that can only run one element at a time. The HLT is no problem as that comes on by timer well before I get up, and is thermostatically controlled to stop it going too far, but the boiler can be a little tedious waiting to heat and if I had the choice I would use two elements. In both cases lots of insulation, and in the case of the boiler I need the lid covering much of the opening (though not fully on) to keep the heat in enough for a properly vigorous boil.

Yep, 13A/3kw is the maximum for a domestic plug, and (amazingly) a double socket is only required to be a 13A unit, not 13A from both at the same time. You can push the better quality ones occasionally but their ratings are related to heat build-up, so if you're intending (as we do) to run them full wack for hours then best avoided if you don't want to shorten their lives.

If you need an extension lead then 'at least' 1.5mm square and if its of the length you're suggesting then 2.5mm is definitely better - more of the power will heat your element instead of the cable. And (yet again as themadhippy says) HO7 RN-F is a good cable - aside from the outdoor suitability which I didn't know about until he mentioned recently, its a rubbery type of flex that IMO is actually more flexible than most plasticy stuff sold as allegedly 'arctic', which is quite useful with thick cables in the cold. Personally, being familiar with electrics, I make mine with a metal MK socket and back-box such as you may see in garage/workshop wiring (but with a cable gland/outlet), because many of the plastic extension-lead/trailing sockets aren't that good if they get warm - and most plugs/sockets do if you run them at max for ages. EDIT: and don't overlook the sockets already on the ring-main either; if they're some cheapo unbranded things they're unlikely to cope as well with really sustained high power as a quality MK socket, even if nominally within their rating. whether or not the ring main itself can take the load depends on what else is running on it - theres not much left if you have two 3kw elements on it.

I've got on very well with immersion elements and have also fitted one to a thick stainless tank (here) - it can take heat for hours has no cutouts (when you bypass the thermostat), is low enough watt-density to not burn stuff on too easily (though it can if theres a load of floury crudd in the boiler) and with the mechanical flange it can be unscrewed and withdrawn from outside. But yes they do need quite large holes; there have been a few people posting on smaller (non-domestic) ones recently. The backer/haden elements are probably easier to fit in some ways, though it sounds like they may have cut-outs in now - someone recently had the cut-out cause problems but I don't know if this was a one-off or not; it seems odd for the boil-dry to activate in normal use.

Some people have found pigtail elements which just need a couple of small holes, i've not heard of problems but they aren't as common as many (and its too early to recommend my currently unproven bendable rod elements). The flat tank is unusual in homebrewing, but many deep fat fryers and things use elements where the tails come up towards the rim before leaving the tank (like this), and I've always known them as Vat elements though I don't know if thats slang or not..

Cheers
Kev

[Fil]

cheers kev good point about the sockets.. that needs a bit more investigation, im happy with the sockets ive fixed all good kit, but i have little suitable for the other end at the moment my current lead terminating sockets do suffer with warmth when missused with 2 elements plugged into the 1 lead, the lead and end plug and socket remain cool however..

the HN07xxx stuff yes top notch but im not gonna be running wheels over the cable or putting it under lot of stress, leaving it in the wet and damp for extended periods or exposing it to massive UV doses so the plasticy 2.5mm stuff it will be... and i will just do the usual checks before plugging in... hopefully the extensions will have only a few uses by the time proper power is sorted later in the year.

well i took a punt on an ebay element.. if i dont dither too long before fitting it i will report if my prospective boil vessel is a success, or keep very quiet on the subject very soon...

[Underground Joe]

Make sure the extension leads are definitely 13A rated, There are an awful lot out there now that are only 10A rated, and have thinner conductors. I even spotted some in B&Q before christmas which were in packs printed "10A extension lead" I noticed they definitely had the thinner cable and on the plug it said fitted with 13A fuse! Fire hazard or what?
lg

Not a fire risk at all and conforms to BS 1363. Pretty much everything you buy in the UK now will come supplied with either a13 amp or a 3 amp fuse. A cable rated at 10 amps might get a bit warm but it won't catch fire if you slightly overload it, unless you've left it coiled.

[Fil]

had a ebay browse last night... Fatal!!
anyway reconsidered element choice and opted for smaller 2500w elements. to suppliment what i have. so my hlt will have a 2500w element, and the boiler a 3kw? and a 2.5kw element.

these are bottom mounted thru a 38.5mm 1 1/2" hole.. easy for the thick walled pot , and easy to sit at the opposite end of the longer rectangular pot.

and gives me leyway running a few hundred watts in lighting pumps extractors etc... without concerns of overloads..

[Belter]

had a ebay browse last night... Fatal!!
anyway reconsidered element choice and opted for smaller 2500w elements. to suppliment what i have. so my hlt will have a 2500w element, and the boiler a 3kw? and a 2.5kw element.

these are bottom mounted thru a 38.5mm 1 1/2" hole.. easy for the thick walled pot , and easy to sit at the opposite end of the longer rectangular pot.

and gives me leyway running a few hundred watts in lighting pumps extractors etc... without concerns of overloads..

Any chance of a link mate? I'm still totally stuck on elements

[DrewBrews]

Are you sure it's a 35 meter cable run?

Not including the cabling in the ring?

Resistance of cable
2.5mm copper = 7.4 mOhm/meter
1.5mm copper = 12.1 mOhm/meter

Assuming the spec of the element is accurate (2.5KW @ 240V)
P=IV, And I=V/R, so R=(V*V)/P
Resistance of element = 240*240V/2500W = 23.04 ohms

If cable is 35 meters of 2.5mm(sq)
Resistance of cable R(c) = 70*0.0074 = 0.518 Ohms
Total resistance = 23.558 Ohms
Current = V/R = 240V/23.558 Ohms = 10.187 A
Power in element = I*I*R(el) = 10.187 * 10.187 * 23.04 = 2391.27 W
Power in cable = I*I*R(c) = 10.187 * 10.187 * 0.518 = 53.76 W

If cable is 35 meters of 1.5mm(sq)
Resistance of cable R(c) = 70*0.0121 = 0.847 Ohms
Total resistance = 23.887 Ohms
Current = V/R = 240V/23.887 Ohms = 11.972 A
Power in element = I*I*R(el) = 10.047 * 10.047 * 23.04 = 2325.85 W
Power in cable = I*I*R(c) = 10.047 * 10.047 * 0.847 = 85.5 W

So using 2.5mm(sq) cable you'll be about 5% down on power
So using 1.5mm(sq) cable you'll be about 7% down on power

And that assumes that you have no voltage drop in the ring before the socket. The reality is the power will be lower still.

[Belter]

I was going to suggest doing it in 4mm. realistically though you shouldn't be running your brewery off an extension lead that long. get an armoured put in. I know its cost but it's worth it