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by livewire
Tue Aug 25, 2009 7:39 pm
Forum: Electrics Forum
Topic: electric motors
Replies: 6
Views: 2764

that's clarified it pretty much! Very interesting KB, thanks again... :)
by livewire
Mon Aug 24, 2009 1:53 pm
Forum: Electrics Forum
Topic: electric motors
Replies: 6
Views: 2764

[quote="kbrownie"]Please Google"allaboutcircuits.com/vol_2/chpt_13/9.html"[/quote] EDIT: Its the four core cable i'm trying to get to the bottom of. Does this Google "tpub.com/content/neets/14177/css/14177_88.htm" explain why we use four core for this kind of circuit? T...
by livewire
Mon Aug 24, 2009 1:42 pm
Forum: Electrics Forum
Topic: electric motors
Replies: 6
Views: 2764

[quote="kbrownie"]Please Google"allaboutcircuits.com/vol_2/chpt_13/9.html"[/quote]

thanks KB, complicated - i did ask i suppose. ;)
by livewire
Sat Aug 22, 2009 6:20 pm
Forum: Electrics Forum
Topic: electric motors
Replies: 6
Views: 2764

electric motors

hi I was helping someone fit electric blinds at Media cityUK in Salford yesterday and would just like to understand a little more on how they work basically. Ok, you may find a picture of the blinds: Google "levolux.com/L_products/internal_blinds.htm" here if you wish. They operate via an ...
by livewire
Thu Jul 30, 2009 8:33 pm
Forum: Electrics Forum
Topic: main tails
Replies: 11
Views: 6402

[quote="kbrownie"]Rarely a problem 180A should be fine on 100Amp main fuse, if the demand of the installation ever did become so high that the main fuse could not cope it's a three phase upgrade.[/quote]


thanks for all your help!
by livewire
Wed Jul 29, 2009 3:00 pm
Forum: Electrics Forum
Topic: main tails
Replies: 11
Views: 6402

[quote="kbrownie"][quote="livewire"][quote="kbrownie"]yep[/quote] So, if ive got this correct, just to repeat what you said in your first post, for a 80A or 100A supplier fuse we will only EVER need either 16mm or 25mm2 csa respectively. So, it doesn't matter if we had ...
by livewire
Tue Jul 28, 2009 5:43 pm
Forum: Electrics Forum
Topic: main tails
Replies: 11
Views: 6402

[quote="kbrownie"]yep[/quote] So, if ive got this correct, just to repeat what you said in your first post, for a 80A or 100A supplier fuse we will only EVER need either 16mm or 25mm2 csa respectively. So, it doesn't matter if we had 20 circuits with a max demand of whatever current (140A,...
by livewire
Mon Jul 27, 2009 7:06 pm
Forum: Electrics Forum
Topic: main tails
Replies: 11
Views: 6402

[quote="kbrownie"]The tails via your cut out will be rated to carry the supply current of the mains fuse this fuse is likely to be rated at either 80 or 100A so tails are likely to be 16 or 25 CSA. When we design an installation we calculated the design current for each circuit first and t...
by livewire
Sat Jul 25, 2009 6:53 pm
Forum: Electrics Forum
Topic: main tails
Replies: 11
Views: 6402

[quote="kbrownie"]Design current or maximum demand?[/quote] hi KB that leads me to another question: I know: Ib < In < Iz But in relation to which 'current' are the size of the main fuse and tails measured? In my previous post, I referred to design current (but am not sure to be honest). S...
by livewire
Sat Jul 25, 2009 9:44 am
Forum: Electrics Forum
Topic: main tails
Replies: 11
Views: 6402

main tails

hi

I know in a domestic environment we're used to a 100A main fuse generally with upto 25mm^2 tails. But what if you're design current Ib is > 100A, say 140A or even 200A? What then? How do we size the tails? Is this upto the supplier?
by livewire
Fri Jun 19, 2009 7:29 pm
Forum: Electrics Forum
Topic: 17th Edition question
Replies: 7
Views: 3564

[quote="kbrownie"]you won't need your OSG for 17th eds exam as that is purely going to ask you about the regulation and any calculations that appear are not as complex as the example you have given, they will be very basic. In reality all the answers should be available in the big red book...
by livewire
Fri Jun 19, 2009 11:21 am
Forum: Appliances in the Home Forum
Topic: 17th Edition question
Replies: 2
Views: 2904

[quote="kbrownie"]your circuit is peotected by 15A, as it's a socket circuit and load can only be assumed, I'd calculate Ib at 15A.
KB[/quote]


that's interesting, thanks KB
by livewire
Fri Jun 19, 2009 8:27 am
Forum: Electrics Forum
Topic: 17th Edition question
Replies: 7
Views: 3564

[quote="kbrownie"][quote="livewire"] I think the whole question is incorrect as it doesn't give enough information to calculate the voltage drop! (i.e. i would need length of cable) in order to work backwards to find the max cable length. if that makes any sense. The only reason ...
by livewire
Thu Jun 18, 2009 4:13 pm
Forum: Electrics Forum
Topic: 17th Edition question
Replies: 7
Views: 3564

[quote="sparx"]hi live wire, gotta be quick as web site KEEPS timing me out 1/2 way through answer... basically no such device as BS3036, 15A, type 2. could be BS3871, 15A, Type 2? you are doing a long winded calc. (incorrectly in your transposition, using 18 twice instead of 35- clue) as ...
by livewire
Wed Jun 17, 2009 8:34 pm
Forum: Electrics Forum
Topic: 17th Edition question
Replies: 7
Views: 3564

17th Edition question

hi A domestic consumer unit on a TN-C-S system uses a 15A Type 2 mcb, to BS3036 to protect a radial circuit wired in 2.5mm^2 two-core pvc insulated cable with a 1.5mm^2 protective conductor clipped directly to a surface. If this circuit supplies socket outlets for hand held equipment, the maximum le...
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