Maximum demand, Please explain.
 

Have been trying to work this out and as much as i can get most of it. Some things still confuse me. Ok from the PEER workbook Appendix C worsheet D.

Determine the maximum demand of a single domestic electrical installation supplied with single phase having the following load.


19 lighting points
6 10A double socket outets
16 single socket outlets
1 15A socket outlet
1 20A socket outlet
3 50W exaust fans
3 1000W strip heaters
12.4kW range
1 4.6kW instantaneous water heater
4 500W lights for tennis court

Ok heres what i undertsand

Load group A(i) 19 lighting points= 3A
3X 50W exaust fans = 135? points going from an example in the regs
So 3+2+2+2=9?

Load group A(ii) 500W lights = non applicable?
Load group B(i) 6 double sockets+16 single sockets =22points?
3 x 1000W strip heaters = 3points(using another example in the book ie 1point for one 1000W heater.) where is this info?
Load group B(ii) 1 x 15A socket outlet = 10A?
Load group B(iii) 1 x 20A socket outlet = 15A?
Load group C 12.4kW range = _____ x 05=______Where do i get this info?
Load group F - water heater 4.6W = ____A?

I hope this makes sense to someone. Help please.

Re: Maximum demand, Please explain.
 

does this make sense

Re: Maximum demand, Please explain.
 

Hi ,

Please clarify where did you get 2amps for fan.

I assume that 19 lights plus 3 x 50w fan

total 22 lights = 3A + 2A.

is this correct.

please give a feed back

will be appreciated.
thanks

Re: Maximum demand, Please explain.
 

:fingerscrossed:

Re: Maximum demand, Please explain.
 

yes that is correct

Re: Maximum demand, Please explain.
 

Can neone plz tell that how many questions in total comes in wiring rule exam in peer

Re: Maximum demand, Please explain.
 

Thanks mate.:thumbup:

Re: Maximum demand, Please explain.
 

Sort of. I dont get this.

Re: Maximum demand, Please explain.
 

Its 4 X 500w = 2000/230 x .75 = 6.25.

hope that explains.

Re: Maximum demand, Please explain.
 

Ok. Before i move on to the next one in the book. I want to make sure i understand this and have it right. I have changed the above to what i think it has to be now. Sorry if it seems like I'm being stupid. But i just cant see it sometimes. Once its pointed out. Its the light bulb going on. :lol:

Re: Maximum demand, Please explain.
 

Ah! Ok. I forgot it was times 4. lol Does the rest look right?

Re: Maximum demand, Please explain.
 

Load group A(i) 19 lighting points= 3A
3X 50W exaust fans = 2A total 3+2 = 5A

Load group A(ii) 500W lights = 4 x 500W = 2000W/230 x 0.75 = 6.5A
Load group B(i) 6 double sockets+16 single sockets =22points?
3 x 1000W strip heaters = 3points= 22+3=25points so 10A+5A=15A?
Load group B(ii) 1 x 15A socket outlet = 10A
Load group B(iii) 1 x 20A socket outlet = 15A + base loading of 15A= 40A?
Load group C 12.4kW range = 12400/230= 53.9(54) 54x 0.5= 27A
Load group E - water heater 4.6W = 4600/230= 20A x 0.33= 6.66A

So overall total would be 100A?

Re: Maximum demand, Please explain.
 

The rest is right except, Group B(iii) is 1x 20 amps socket = 15amps

Total demand is about 85.15amps.

Re: Maximum demand, Please explain.
 

Ok thanks. will attempt the next sheet maybe tomorrow and post back here to see if I'm right.

Re: Maximum demand, Please explain.
 

The correct answer is 95.16 amps

Re: Maximum demand, Please explain.
 

Can you show us how you get that please?

Re: Maximum demand, Please explain.
 

19 lig point 3amps

6 10 a double skt outlt
16 10a singl skt outlt 15 amps
3 strip heater 1000 watt

1 15amps skt outlet 10 amps
1 20amps skt outlet 15amps
3 exhaust fans 2amps
1 12.4 kw range 27 amps
1 4.6kw instant water heater 6.66amps
4 500watt tennis light 6.50amps

total 85.16 amps

Re: Maximum demand, Please explain.
 

You gave 2 different amounts

Re: Maximum demand, Please explain.
 

old one was mistyped mate.

Re: Maximum demand, Please explain.
 

Ok have been working through the next few shets of MD. Will put up these sheet by sheet and lets see if I'm right or if you have the same answers. Ok.
Q2 Same category.

Determine the maximum demand of a single phase 240V domestic installation.

28 Lighting points 3A+2a = 5A

8m Lighting track 8 x 2A = 16A

13 10A single socket outlets
+
9 10A double socket outlets
+
2 50W exhaust fans
+
1 1200Watts strip heaters = 13+9+2+1=25points so 10A + 5A = 15A

1 14.5KW range 14500/230 = 63 x 05 = 31.5A

1 3.4kW storage H.W.S. 3400/230 = 14.8A

1 3.0kW clothes drier N/A



Total = 82.3A



Right or wrong?

Re: Maximum demand, Please explain.
 

exactly same answer,Thanx

Re: Maximum demand, Please explain.
 

Question 3

Determine the maximum demand of the heaviest loaded phase in a domesticv electrical instalation having the following load-

21 Lighting points 3 + 2 = 5A

28 10A single socket outlets
+
8 10A socket outlets = 10A + 5A = 15A

1 range(2 hotplates 6kW each and 6.8kW oven) 18800/230=81.73x0.5=40.86A

1 air conditioner- (single phase 4.8kW) 4500/230 = 19.56 x 0.75= 14.67A

1 clothes dryer - ( single phase 4.8kW) N/A

1 washing machine - ( single phase self heating - 3.2kW) N/A

1 3phase instantaneous water heater (5.3kW per phase) 5300/230 = 23 x 0.333= 7.67A per phase

1 3 phase motor rated at 7.5A per phase = 7.5A per phase



Total 90.7A


Right or wrong?

Re: Maximum demand, Please explain.
 

For question 2 Max Demand I have got, total 68.3.

28 Lighting points 3A+2a = 5A

8m Lighting track 8 x 2A = 16A

2 50W exhaust fans = 2

ie total points is 28+ 16 + 2 = 46points

3A+2A+2A = 7A
see egin reg C2.3.2.1 load group A(1)

7A+15A+31.52A+14.78A

Total 68.3Amps

Please let me know if this correct.

Re: Maximum demand, Please explain.
 

The 16 for the track is not points but amps.

Re: Maximum demand, Please explain.
 

Please read note d on pg 358 for lighting

Re: Maximum demand, Please explain.
 

Also note in the question the voltage 240 is used.

for lighting track read d pg 358,

2 points per metre of track
ie

8 x 2 = 16 points

final answer [B]66.41 Amps[/B].

please check, I already check with one of m:fingerscrossed:y mate same answer as mine.

Re: Maximum demand, Please explain.
 

Thanx for correcting us askar.yea i hve also chkd again u r right.

Re: Maximum demand, Please explain.
 

Determine the maximum demand of a single phase 240V domestic installation.

28 Lighting points
+
8m Lighting track + 2 50W exhaust fans = 28+16+2= 46 points. Which is 3+2+2=7A

13 10A single socket outlets
+
9 10A double socket outlets + 1 1200 watts strip heaters = 13+9+1= 23 points so that would be 10+5=15A

2 50W exhaust fans

1 1200Watts strip heaters

1 14.5KW range 14500/240 = 60.41 x 0.5 = 30.2A

1 3.4kW storage H.W.S. 3400/240 = 14.16A

1 3.0kW clothes drier N/A



Total = 66.36A

This is what i get after revising the above. Just wondering where you get the extra 0.5A from?

Re: Maximum demand, Please explain.
 

Yes your answer is correct.:thumbup:

Re: Maximum demand, Please explain.
 

What about this one?

Re: Maximum demand, Please explain.
 

Foe Maxmium Demand Question No 3.

I was looking at the example on pg 360.

You have to put in 3 phase load and balance it ,the answer they looking for is the max current in the phase.
The trick is ensure try to balance the load as close as possiable,
I wiil attempt later,

let me know if you had worked out.
thanks.

Re: Maximum demand, Please explain.
 

I did try and balance it.:thumbup:

Re: Maximum demand, Please explain.
 

Determine the maximum demand of the heaviest loaded phase in a domesticv electrical instalation having the following load-

21 Lighting points 3 + 2 = 5A

28 10A single socket outlets
+
8 10A socket outlets = 10A + 5A = 15A

1 range(2 hotplates 6kW/230v =13.04A

6.8kW oven) 6800/230= 14.78A

1 air conditioner- (single phase 4.8kW) 4500/230 = 19.56 x 0.75= 14.67A

1 clothes dryer - ( single phase 4.8kW) see reg pg360 = 10.43A

1 washing machine - ( single phase self heating - 3.2kW) = 6.96A

1 3phase instantaneous water heater (5.3kW per phase) 5300/230 = 23 x 0.333= 7.67A per phase

1 3 phase motor rated at 7.5A per phase = 7.5A per phase



arrange into 3 phase

RED YELLOW BLUE

5A

10A 5A

13.04A 13.04A

14.78A


6.96A

10.43A

14.67A

7.67 7.67 7.67

7.5 7.5 7.5


Total


Red= 50.17 Yellow= 43.64 Blue= 44.62


Max demand red phase= 50.17A

I hope this is right,can some one check this please.:fingerscrossed:

Re: Maximum demand, Please explain.
 

re balance red= 45.17 yellow = 48.64 blue = 44.62

total demand = yellow phase = 48.64A


is it right please any one

Re: Maximum demand, Please explain.
 

Hi Has any one done question No 3 on maximum demand.on peer work book

Re: Maximum demand, Please explain.

--------------------------------------------------------------------------------

re balance red= 45.17 yellow = 48.64 blue = 44.62

total demand = yellow phase = 48.64A


is it right please any one

Please reply.:fingerscrossed:

Re: Maximum demand, Please explain.
 

I got 69.03A , 42.84A and 43.82A

Re: Maximum demand, Please explain.
 

Question 4 i got 272.76A , 224.88A and 203.31A. Not sure if these are right. Views and opinions please.

Re: Maximum demand, Please explain.
 

BTW the last calulation was worked out a while back. So it may be totally wrong.

Re: Maximum demand, Please explain.
 

Q4 is not right,I think,please see example on pg361.

Re: Maximum demand, Please explain.
 

Is this not total 72,9A?

If got
Ai)28p+16+2=46p= 7A
B)13p+18+1= 15A
C)30,2A+6,5A=36,7A
F) 14,2A
total: 72,9A