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Topic Title: Maxmum demand
Topic Summary: Calculating
Created On: 19 January 2013 11:30 AM
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 19 January 2013 11:30 AM
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Nedd

Posts: 9
Joined: 18 February 2012

Hi all
I was told by a lecturer an acceptable method of calculating maximum
demand as required on EIC. I think it was, add all fuses or mcbs at the
db together then divide the total by 40 the remainder is the demand
is this right or not. If not which is the best way to calculate the load
Thank you .
 19 January 2013 12:35 PM
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rocknroll

Posts: 8881
Joined: 03 October 2005

Not quite, the demand factor is less than 1, the diversity factor is greater than 1, the most common method used by the DNO's for estimating the demand was multiply by the factor 0.4.

regards

-------------------------
"Take nothing but a picture,
leave nothing but footprints!"
-------------------------
"Oh! The drama of it all."
-------------------------
"You can throw all the philosophy you like at the problem, but at the end of the day it's just basic electrical theory!"
-------------------------
 19 January 2013 02:22 PM
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kj scott

Posts: 2144
Joined: 02 April 2006

Maximum demand will vary for different types of installation, and should be based on experience. A factor of 0.4 is not suitable for the consumers installations, even if it was appropriate for the distributor.

There is some guidance in the IET publications, GN1 and the On site guide, but prior knowledge is the key to economic assessment.

-------------------------
http://www.niceic.biz
 19 January 2013 03:28 PM
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rocknroll

Posts: 8881
Joined: 03 October 2005

You will find the estimation method for maximum demand of an installation in your IET Electrical Installation Design Guide with the appropriate IEC curve, fairly basic stuff really and perhaps show it to your lecturer.

regards

-------------------------
"Take nothing but a picture,
leave nothing but footprints!"
-------------------------
"Oh! The drama of it all."
-------------------------
"You can throw all the philosophy you like at the problem, but at the end of the day it's just basic electrical theory!"
-------------------------
 19 January 2013 05:57 PM
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ebee

Posts: 5743
Joined: 02 December 2004

I disagree about adding all the fuses together for a start.

Just for example.

Two exactly equal installations with exactly equal usage at all times.

One has 10 circuits total.
The other has 20 circuits total (half as many points on each circuit).

The Max demand should be the same.

OK potentially the one with twice as many circuits might be capable of becoming twice as overloaded at any time but the maximum demands should be similar.

-------------------------
Regards,
Ebee (M I S P N)

Knotted cables cause Lumpy Lektrik
 19 January 2013 06:37 PM
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Nedd

Posts: 9
Joined: 18 February 2012

Originally posted by: rocknroll

You will find the estimation method for maximum demand of an installation in your IET Electrical Installation Design Guide with the appropriate IEC curve, fairly basic stuff really and perhaps show it to your lecturer.



regards

Just found an earlier post of yours back in 2010 on the same subject A good in-depth post, told me all I wanted to know and more. Thanks
 20 January 2013 10:41 PM
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Westonelectrical

Posts: 85
Joined: 26 November 2012

VxI divide by 1000 done..
Statistics

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