maximum demand.

[madeinengland]

hi guys. this is gonna be a long question so please bare with me.

i have my 2392 practical coming up.i'm fairly confident of the testing to be done on the board. the problem i'm gonna have is the three certificates to fill in. schedule of tests i'm fine with. schedule and inspections i'm ok with. but the certificate itself i haven't even seen and we've been doing this course for 8 weeks with my exam in two weeks time but i won't get a chance to see one cos next week half the class are in their practical exam and the rest of us won't be allowed in. anyway on the certificate it asks for maximum demand. i believe this is done using diversity.

here's what we have.

1)1x16 amp radial circuit with 1 socket.

2)1x6 amp lighting circuit with 2 way 1 lamp.

then rcd protected circuits of

3)1x40 amp cooker point with 1 socket

4)1x32 amp ring circuit with 4 sockets and 1 spur.

now i make the maximum demand this

1) 100% of 16 amp =16A

2)66% of 6 amp =4A

here's where i have problem on cooker

3)1st 10A then 30% of remainder over 10A so 30% of 20A=6A then add 5A for the socket outlet making the cooker circuit 21A

4)100% of 32A=32A.

i make it 16A+4A+21A+32A=maximum demand of 73 amps.

help me guys is this correct??????????

 

[bulmer]

I make it 64.8 amps.

 

[meerkat]

Hi Madeinengland, I thought it was

lighting 66 % of demand (6) = 4 Amps

cooker (40) 10A then 30 % of remainder plus 5 Amps for incorporated socket 10 + 9 + 5 =24Amps

Ring 100% (32) = 32Amps

Radial 40% (16) = 6.4Amps

total 66.4Amps

Page 97 OSG column 2 individual dwellings

hope this helps, (Meerkat)

 

[NozSpark]

As the meercat says, but...

66% of lighting ------ @ 100w per fitting unless it's a fixed load (in which case it's the stated wattage)

 

[Andy™]

As the meercat says, but...66% of lighting ------ @ 100w per fitting unless it's a fixed load (in which case it's the stated wattage)

shouldnt we change 100w to 60w... after all, you cant get 100w bulbs anymore...

 

[philbas]

OK, my first stupid question, I did promise some.

2)1x6 amp lighting circuit with 2 way 1 lamp.

Only one lamp.

How can you apply diversity to it, its on or off.

Sorry if this is obvious to you all but I haven't even done the "what colour is a fire extingusher exam yet"

 

[Andy™]

OK, my first stupid question, I did promise some.2)1x6 amp lighting circuit with 2 way 1 lamp.

Only one lamp.

How can you apply diversity to it, its on or off.

Sorry if this is obvious to you all but I haven't even done the "what colour is a fire extingusher exam yet"

then you would not apply diversity to that circuit....

... and for fire extinguishers.... they are now all red, with a little coloured bit to ID what it is.... just to make it harder for you to get the right one in case of emergency

 

[philbas]

So would I be correct in thinking the 66% doesnt apply here and it should count as 6A ?

 

[Andy™]

So would I be correct in thinking the 66% doesnt apply here and it should count as 6A ?

no. you max load on that circuit would be your light... i.e if it was a 150W light, your max demand would be 150w. or 0.65A

 

[philbas]

[quote name='Andy

 

[Taofeek]

Hello guys!! am new on here, but i have a questions please,am on my level 2 and just did my 203 exam last night whice i got pass,my main question is all my exams that i did i got pass for them all,is pass good? coz am not happy at all.....

 

[madeinengland]

Hi Madeinengland, I thought it waslighting 66 % of demand (6) = 4 Amps

cooker (40) 10A then 30 % of remainder plus 5 Amps for incorporated socket 10 + 9 + 5 =24Amps

Ring 100% (32) = 32Amps

Radial 40% (16) = 6.4Amps

total 66.4Amps

Page 97 OSG column 2 individual dwellings

hope this helps, (Meerkat)

cheers meerkat. i guess you'd say simples.

i did it in class 2 weeks ago and got 67amps. but every time i've looked at it since i get 73. i wasn't sure on the cooker cos (don't have osg on me at the mo) it says "take 1st 10 amps then 30% of remainder over 10 amps." i wasn't sure if you took the whole of the remainder (30A)or take 30%of the remainder over 10 amps meaning 20A.the thing thats got me confused is that in 2330 L3 we did this alot but it was always on design of the circuit where you know what appliances your using. i.e 12KW cooker what CB do you need using diversity.but if you don't know what cooker is gonna be connected how can you use diversity on that circuit?

 

[ianmacd]

Hi Madeinengland, I thought it waslighting 66 % of demand (6) = 4 Amps

cooker (40) 10A then 30 % of remainder plus 5 Amps for incorporated socket 10 + 9 + 5 =24Amps

Ring 100% (32) = 32Amps

Radial 40% (16) = 6.4Amps

total 66.4Amps

Page 97 OSG column 2 individual dwellings

hope this helps, (Meerkat)

Hmm just answered this same question in another thread. Wierd.

I did get a different answer for cooker though as I read app1 as 10A + (30% of f.l.) which to me is 10A + (30% of 40A) (+ 5A for socket) so I got an answer 3A higher than yours.

 

[sparkytim]

Page 96 OSG

TABLE 1A

household cooking appliance

The first 10A plus 30% OF THE REMAINDER OF THE RATED CURRENT + 5 A for a socket-outlet if incorporatedin the control unit

 

[ianmacd]

Page 96 OSGTABLE 1A

household cooking appliance

The first 10A plus 30% OF THE REMAINDER OF THE RATED CURRENT + 5 A for a socket-outlet if incorporatedin the control unit

Which contradicts 1B on 97.

10A +30% f.l. of connected cooking appliances in excess of 10A + 5A if a socket-outlet is incorporated in the control unit.

 

[madeinengland]

Hmm just answered this same question in another thread. Wierd.

oh yeah. that would be me. :red card double threading

 

[Andy™]

OK that makes sense, thanks.But it does raise another question in my mind.

1)1x16 amp radial circuit with 1 socket.

Given that we only have one socket, and whatever is plugged in should have at a max a 13A fuse, Is not the max load 13A rather than 16A ?

Edit: No It doesnt, unfused adapter pluged into socket headbang

max demand would be 13A, which is the max load on a socket.

but in some cases, your MD could be 0.5A (i.e radial to loft for TV amp)

 

[ianmacd]

[quote name='Andy

 

[Andy™]

What if its a double socket?

go read the rating on the back of any double socket - 13A (although many are capable of more without overheating, but the cheaper ones are not)

 

[ianmacd]

[quote name='Andy