max demand peer workbook question help please!
 

if i have a block of 40 units how do i determin the value of 32 units with 2.0kw permenently connected strip heaters?
Max demand table c1 columb, 5 B1. STATES 21 OR MORE LIVING UNITS PER PHASE = 50A + 1.9A PER LIVING UNIT so is that 50A straight off plus the sum of 32 units multiplied by 1.9A?
Same problem with the 10A socket outlets for all 40 units. Is it 50A straight plus 40 units by 1.9A or 50A for the 21 units and 1.9 by the remaining 19 units:confused:
Cheers lads. its on page 27 of the peer workbook if anyone has it
Also how do i get the value of 1 3phase pump motor 4.8kw(7.5A per phase) communal loading, why does it say 7.5 amps per phase? im an hour at this one, now very confussed, wish i had of been a chippy

Re: max demand peer workbook question help please!
 

This is the solution form the answer sheets peer gave us to check our work.

Re: max demand peer workbook question help please!
 

Cheers pal Ill have a look at it again on monday! have you got the correct answers to alot of the calculation questions? Would be a great help so I can tell if my answers are correct. The examples in the books are not the best.
Cheers

Re: max demand peer workbook question help please!
 

yeah but you would have to wear a hat 24/7 to cover the labotomy scar :rofl:

Re: max demand peer workbook question help please!
 

that's your nameplate rating for the motor.

Re: max demand peer workbook question help please!
 

Bugger just got to this part, it was all going so well

Re: max demand peer workbook question help please!
 

Think you have to divide the units by 3 to give you units per phase

= 13, 13, 14. so youd be using the 6 to 20 living blocks per phase column.

Re: max demand peer workbook question help please!
 

me too mate i was flying tru this unil now. Ill post my answers for all the max demand questions so we can confirm if we got the same answers. I need this license fast Im tired of labouring

Re: max demand peer workbook question help please!
 

Hi all

It is a worry when you are sat at home trying to do it on your own but I attained my licence the PEER route back in Feb and I can promise you if you have a fair go at the work book and do as much as you can, the guys at PEER will go through the things you are stuck on when you do your revision day.
Maximum demand is a big part of the exam and they go over about 4 examples with you on the revision day, they show you how they like it setting out and everything.

Jon is right though when you are working out living units before you start doing any calcs split the units up over the 3 phases and set it out on a spare piece of paper.

For example 40 units and then list the loads

13 13 14
Equipment load group calc Red White Blue

Lighting A1 14 X 0.5 7A

Note remember to read the question alot of the time they are only asking for the heaviest loaded phase.

Hope this helps guys, feel free to send me a message and ill do my best to help

Mike

Re: max demand peer workbook question help please!
 

Just dug out my workbook for you Paul the calc for the socket outlets is
50 + (14 x 1.9) = 76.6A the 14 being because you have split the units across the 3 phases like i showed in the example of the above post.
Strip heaters- 2000 / 230 = 8.7A

12 x 8.7 x 0.75 = 78.3A the 12 being the number of units ie 10, 10, 12 and the 0.75 being 75% of the connected load.

For the motor question no calculations are required simply add 7.5A to the heaviest loaded phase.

Mike

Re: max demand peer workbook question help please!
 

Nice one Mike, thanks for your help

Re: max demand peer workbook question help please!
 

Yea cheers mate thats great stuff, fair play

Ambient Temp Question
 

P68 OF THE WORKBOOK

Question 13: It is intended to install 120mm 3phase and earth .6/1 kV, copper, sheathed, V-75 insulation cable, enclosed in non metallic wiring enclosure in air, together with other 4 circuits. Ambient Temperature of the location is 50 degreesC, conductor temp. 75deg.C

What will be the resulting value of current carrying capiacity of this cable?

I can do the first half but im lost with the ambient temp part of it, could be that its mid 30s today and the sun is beaming in my window!
Any help would be great lads
thanks

Re: Ambient Temp Question
 

Hi Paul,
Im struggling a bit with these cable calcs, have you got an anwser for Q13, id like to compare!

Cheers, jon

Re: Ambient Temp Question
 

My answer is dont worry about it, ive sat and passed the exam last week, they dont check the work book just flick tru to see that youve made an attempt. Same goes for the ETSU section at the back of the workbook they know its impossible and will be removing it from the workbook soon. They go tru anything your stuck on the day before the exam. its not too bad but alot of people struggle on the zint and zext formulas for calculating impedance, well worth looking at we got 4 questions on it. Glad ive got it now but i cant afford the $350 for the SA licence or the $350 for the Vicv License:frown: