Cable Length

[BrotherMalice]

I am in the process of finalising my boiler & am wondering about cable lengths, I have yet to make up the power cables and was wondering what length cables I can use, I am hoping to run 1 cable from upstairs and one from downstairs to be on seperate rings to reduce the risk of melting something :)

 

[calumscott]

If you are going to those lengths, do you not have a spare breaker slot in your distribution board?

Pop it behind an RCD and build your brewhouse into it's own protected ring?

 

[BrotherMalice]

Sadly renting so cant play with the electrics hence wanting to run 2 cables from different rings

& for me, brewhouse equates to kitchen/garden at the moment

 

[calumscott]

Ah, got you!

In that case it sounds like a sensible plan.

Do you actually know the layout of the sockets on the ring? It's always best to take spurs with heavier load from the middle of ring so if you knew the layout you could have one running from roughly the middle of each ring which makes it the least stress possible.

 

[BrotherMalice]

not a clue at all sadly, hading seen some of the wiring in the house it could be anywhere, I think I would run 1 wire from the back bedroom upstairs and 1 from the kitchen, I need to find a way of getting a switch inline though so that I can switch them off locally rather than having to run around trying to find the switches.

When I was testing in the kitchen with 1 element, I had it on for about 1/2 hour and when I switched it off at the socked I saw a spark/flash behind the socket - I assume that is not a good sign?

 

[calumscott]

Get yourself a couple of switchable 13amp extension sockets and take the socket ends off.

Use the cables and plugs as the tails from your elements.

Then get a roll of 13 amp cable and a couple of plugs and make yourself suitably long switchable extension leads from those and the socket ends from before.

Job done. :thumb:

 

[calumscott]

Oh, and don't worry about sparks inside sockets, perfectly normal, just the lecky arcing as the switch contact is broken...

Watch what happens in light switches and appliances and what not... Sparks everywhere...

 

[BrotherMalice]

struggling to find single socket switched extensions atm, will look further

 

[BrotherMalice]

single is definately the challenge can find seperate sockets but not extensions

 

[BrotherMalice]

Do you think this would work?

http://www.wilkinsonplus.com/extension- ... r8RA%3D%3D

keep the other sockets switched off?

 

[theboytony]

What size batches are you planning on making. If it is five gallon why not just start with one element, will just take a bit longer to come to the boil but when it is a rolling boil one is more than enough, in fact one element uncontrolled can be a bit to powerful for a five gallon batch

 

[BrotherMalice]

I was aiming for 23l but being more realistic I think I am going to go with 20l Got the elements fitted now but you make a valid point about only using the one element it is something that I will think about, still need a switch near the boiler though for control, hoping to brew outside if possible to avoid steam/condensation issues in the kitchen.

 

[miker7301]

still need a switch near the boiler though for control, hoping to brew outside if possible to avoid steam/condensation issues in the kitchen.

Please can you tell me the cable lengths you'll have to use, as this will affect the voltage drop along the run, then you can factor in the rise in current needed to run the kettle elements.

Just using a 13 amp extension may not give you the result you expect.

Running high ampage kit over a long distance requires bigger cable, I'm about to embark on a AG kit in my new garage, and am putting in a 10mm cable to cover the kettles. That is much thicker than the 1.5mm cable you are considering on your 13amp extension. (but I'll run stage light tests as well) I'd say 2.5 mm is necessary as a minimum (but this depends on your length of cable runs)

Understand that electricity loses it's power (so to speak) with the resistance of the cables, and more quickly than you think. The regs (17th edition) list safe allowed voltage drops over distance. Here is a calculator to help.

the regs also state that outdoor temporary power supplies should use H07-RNF for cable runs. This cable is very robust, and is used widely in outdoor rigs for concerts, events, and festivals.

Correctly rated RCBO's are also a must IMHO, not just a fuse...

I'm all for home brewing, but be safe with electricity. You can fu3k up a brew many times, but fu3k yourself up, and you'll never brew again..

The cost of my advice is free, but you should check, and recheck your calculations depending on your circumstances. I freely give advice, but do not take any responsibility if you hurt (or worse) yourself. If in doubt, consult a qualified electrician (which I am not)

 

[BrotherMalice]

I appreciate your help there, really good info!

I am looking ar maximum run of 10m for each one, one of them should be far shorter, I will look into it in more detail at the weekend.

Thanks!

 

[miker7301]

Sorry, I am in work mode....
Your a home user, brewing in your private property, not opening up to the public.
H07 RNF is probably overkill, as your using domestic plugs. Look at H05 RR, aailable from DIY shops, and a fraction of the cost. I'd still advise 2.5mm to be safer, have you guestimated your 10m run, or actually measured it. From experience, I've guestimated 10 m in the past, and been way off!

 

[BrotherMalice]

definate guestimate - will measure at the weekend

 

[calumscott]

+1 on the 2.5. Apart from the physics bit it's really nice to work with.

 

[BrotherMalice]

Got this stuff to have a go - had the boiler on for about 2 hours today (closely monitored) and no problem with the cable at all although the plug did get noticably warm?

http://www.diy.com/nav/fix/electrical/c ... 5m-9290557

 

[Andyhull]

Your houshold socket cables should be a minimum of 2.5mm for use of upto 13amp and your lighting should be 1.5mm for the use of upto 5amp.

You would be absolutely fine using a double socket from your wall as it will probably be part of the downstairs ring main.
Think of it this way, would you use your kettle and toaster at the same time?
I know i certainly do and together they draw the same power amps as each other hence the same as running 2 kettle elements.

Think of what your down stairs ring main supplys, multiple TV's DVD's Sky boxes, extra plugged in lighting toaster kettle (etc) (etc).
You don't have to run long lengths of cable as the long lengths as stated previousely demand a certain amount of amps to push the current to it's desired location.

I have ran my boiler around 10 times now on a full rolling boil for an hour each time trying to calculate evaporation rates and have had no problems, i start with both elements running until i get to a rolling boil then turn the second element off as i only need the 1 running to sustain the boil.

Andy

 

[miker7301]

Andy,
A domestic ring main is 2.5mm that is correctbut it is a ring main, The clue is in the name
Long cable runs like the OP enquired about is an extension, and not part of the ring main.
Any fool knows that the longer the cable run, the higher the resistance. However, when a long run is needed, you need to specify the correct size cable. Your analogy of the kettle and roster has many holes.
Check the power rating of both the kettle and toaster. I bet your toaster draws a much lower current (thats amps) than your kettle. Both the toaster and kettle use separate cables, and whilst they are plugged into the same double socket, the cabling behind is a ring main.
So, the 2.5mm ring main has an easy theory behind it, resistors in parallel so, total resistance=(1/R1)+(1/R2)+(.....) Therefore, in a ring main, the total resistance in the ringmain from mcb to socket is less than lowest resistance of one of its component parts.
The kettle elements the OP asked about are to be run at a distance from the ringmain on a single cable. 10 metres does not sound much, but in terms of maximum voltage drop (and therefore current rise) is significant, especially when you factor in the load demand.
Bigger cables have less resistance, and therefore, the losses to the cable are lessened (back to the ring main - there is 5mm CSA cable to your socket) so, to reaffirm, I still advise 2.5 mm cable, not to be funny, or to make someone pay more than they should, but to be safe, and legal with regard to the electrical regs in this country.