Maximum demand

[green-hornet]

1 x 32a cooker

2 x 32a sockets

1 x 16a imm heat

2 x 6a lights

1 x 6a smoke detectors.

add 32+32+32+16+6+6+6=130x0.42=54.6

Now round that up and you get a realistic value for maximum demand on a small installation.

 

[SPECIAL LOCATION]

1 x 32a cooker2 x 32a sockets

1 x 16a imm heat

2 x 6a lights

1 x 6a smoke detectors.

add 32+32+32+16+6+6+6=130x0.42=54.6

Now round that up and you get a realistic value for maximum demand on a small installation.

tis what I just said Mr H!

0.42x(130a)=54.6a Maybe not far off?

I think one area where the totalling of MCB's could become a bit out of step is say if you split a few more circuits to provide a bit more discrimination on 17th ed boards... or to ensure Volt drop ok..

e.g. I may quite often add another lighting circuit for outside lights, which will obviously be on a 6A MCB..

or put two downstairs rings.. one kitchen & util (32A) another lounge, dine, conservatory, hall (20A)

so extra MCB's BUT no extra REAL load?

This is where the 'competent' person will make reasonable assessments of demand using a suitable method,

As GH says... there are plenty of documents to assist with these calcs if you have any doubts!

 

[0151]

2. Clampmeter on tails. Yeah - cool. IF you could stand there for an "average" day, and read the peak usage. M.D. doesn`t change with seasons - usage does. Is the customer having a shower whilst you`re there? (You wish!). NO? then you are not reading the Maximum Demand.

QED again (sorry)

nobody has to get into the shower you can just turn it on along with all other appliances and that will give you a damn good idea. plus I have just scrolled thru a few test certs and compared to my clamp readings the 0.42 method is actually quite close within 4 to 6 amps

thanks

 

[Voltimax]

No method is written in stone.

Anyone designing installations or indeed adding to them uses their experience. I do believe that is written in the diversity section of the OSG.

 

[SPECIAL LOCATION]

nobody has to get into the shower you can just turn it on along with all other appliances and that will give you a damn good idea. plus I have just scrolled thru a few test certs and compared to my clamp readings the 0.42 method is actually quite close within 4 to 6 ampsthanks

or just read the power rating and divide by voltage.

current = power/voltage!

e.g.

9k shower 9000/230 approx 40 amps

2.2k kettle 2200/230 approx 9.5amps

allow rough guide..

8.5amp for 2.0k appliance

11amps for 2.5k appliance

13amps for 3.0k appliance

 

[batty]

Its just a case of using your loaf. If you install a 10.8kw shower and the main fuse is only 60 amp there is a good chance at some point the main fuse could blow probably at christmas time. If you install a large current drawing load on an install and it only has a 60 amp fuse it would be a good idea to get it upgraded.

Batty

 

[Andy™]

Its just a case of using your loaf. If you install a 10.8kw shower and the main fuse is only 60 amp there is a good chance at some point the main fuse could blow probably at christmas time. If you install a large current drawing load on an install and it only has a 60 amp fuse it would be a good idea to get it upgraded.Batty

not always... i have an 9.5KW shower, electric oven and hob. along with all the other usual stuff plugged in. and its never blown the 40A fuse.

 

[batty]

not always... i have an 9.5KW shower, electric oven and hob. along with all the other usual stuff plugged in. and its never blown the 40A fuse.

But your a tight wad and only have one on at a time.

 

[Andy™]

But your a tight wad and only have one on at a time.

not very often shower and cooker are used at same time, but does happen every so often. fuse probably gets hot, but shower isnt used long enough for it to blow

 

[avinalarf]

I'm a bit late in the day catching up with this thread. I happy to say I had done my MD using diversity etc and came up with 76A.

My confusion now is how do you know what the rating of the main fuse is when it says 60/80A.

 

[Andy™]

My confusion now is how do you know what the rating of the main fuse is when it says 60/80A.

you dont know unless you remove it

 

[avinalarf]

Andy, do you mean "you don't know unless you remove it"? Then what???

 

[Andy™]

Andy, do you mean "you don't know unless you remove it"? Then what???

yes, i do mean that (post edited)

 

[Evans Electric]

assuming... Demamd is demand?{dont you just luuuuv Typo's?}Applaud Smiley:x

with an abacus or slide-rule....

oh bum!!Blushing

Am i showing my age again?

Deke remembers Abacus's & slide-rules?

and log-tables probably?

:coat

I refuse to answer this , this is agism this is, log tables indeed, anyway they were no good without the anti-logs ( or so I am told) .

I remember Abacus's records were always hits, Dancing Queen, Winner takes it All, etc

I,m not an old phart, in fact I,m shopping tomorrow for a baseball cap , but can't seem to find the ones with the peak at the back, any ideas.

Oh the thread... yes .. some good comments, TBH I've been taking an educated guess at it for years , I await the flak.

Deke

 

[SPECIAL LOCATION]

I refuse to answer this , this is agism this is, log tables indeed, anyway they were no good without the anti-logs ( or so I am told) . I remember Abacus's records were always hits, Dancing Queen, Winner takes it All, etc

I,m not an old phart, in fact I,m shopping tomorrow for a baseball cap , but can't seem to find the ones with the peak at the back, any ideas.

Oh the thread... yes .. some good comments, TBH I've been taking an educated guess at it for years , I await the flak.

Deke

we can get you to answer Deke!

I shall get one of Apaches tranquiliser guns wot can subdues a whole horse!

then you will talk ] ] ]

anti logs AND uncle logs...

and don't forget great nephew logs!!!! ; \ ; \ ; \

:coat

 

[Andy™]

t can subdues a whole horse!then you will talk ] ] ]

use the tranq and i dont think they will be talking even if they wanted!

 

[Evans Electric]

They were a bloody nightmare, I wonder if I could have attained an ONC or HNC if calculators had been invented. No I'm being over ambitious , I was never going past the C&G,s I'm afraid.

Log tables went the way of the old currency, 12 pennies = 1 shilling, 20 shillings = 1 pound, 240 pennies = 1 pound ,2 halfpennies = 1 penny, 4 farthings = 1 penny, half a crown = 2/6d or half a dollar, 2 x 2/6d = 5 bob a guinea was 21 shillings , two threepenny bits to a tanner, bloody hell what a system !!

Welcome to the metric system.

Specs will remember all this because he is really ancient and remembers rawlplugging tools and Dixon of Dock Green.

Deke

Deke

 

[Apache]

Specs will remember all this because he is really ancient and remembers rawlplugging tools and Dixons of Dock Green.

Deke

Deke

They are all over the counrty now. They sell TV's and stuff............

:coat

 

[Evans Electric]

Oh very funny Patch !! Just a minute , how did you edit my post to make the name plural ? Didn't know you could do that .

deke

 

[Andy™]

Oh very funny Patch !! Just a minute , how did you edit my post to make the name plural ? Didn't know you could do that. - I can edit your post. at least in the quote, like this, but not the original .deke

?:|