Max demand and diversity

[telectrix]

provided that you can access the fuse to see the rating. otherwise, base it on the size of the tails.

 

[ackbarthestar]

Not sure i would agree with sizing the Max. Demand on the size of tails. Its not uncommon to see 100A Service fuses (well that's what it says on the packet) and 16mm2 tails.

 

[telectrix]

Not sure i would agree with sizing the Max. Demand on the size of tails. Its not uncommon to see 100A Service fuses (well that's what it says on the packet) and 16mm2 tails.

my thinking there is that the max. CCC of the tails would limit the demand. e.g. if 16mm tails, max. demand 80A, irrespective of the fuse rating. just throwing the idea out.

 

[Brightspark2]

its rule of thumb just for domestics.
if you break it down for each circuit sperately you can get the final figure down even lower.
but commercial / industrial diversity is a whole different ball game lol

Domestic x 0.4
Commercial x 0.6
Industrial x 0.8

Seen that recommended somewhere, wiring matters maybe...

 

[ackbarthestar]

my thinking there is that the max. CCC of the tails would limit the demand. e.g. if 16mm tails, max. demand 80A, irrespective of the fuse rating. just throwing the idea out.

I suppose its a possibility, Anyway, domestically speaking, Its quite difficult, and expensive, to consume 80A on a continuous basis unless you have tropical plants in the loft :39:imp2:

 

[telectrix]

mmm... pass the dutchie.

 

[Knobhead]

You cooking Tel?

 

[Engineer54]

Domestic x 0.4
Commercial x 0.6
Industrial x 0.8

Seen that recommended somewhere, wiring matters maybe...

I wouldn't just go applying those factors to commercial and industrial installations. Now your in the realms of real electrical installations and as such, need to be assessed far more stringently than a typical domestic installation....

 

[Knobhead]

Where did 0.8 for industrial come from? That’s got me curious.

 

[johnboy6083]

There Are diversity figures suggested in the Electicians design guide by the IET. It has paper mills, rolling mills ect. I'm not sure i would 100% go with it though!

 

[ackbarthestar]

Where did 0.8 for industrial come from? That’s got me curious.

Me too....

There's all sorts of things to take into consideration which are often specific to the installation

 

[Guest55]

anything bigger than domestic and i apply diversity on a circuit by circuit basis , trying to use a single generalised figure on a large commercial install will end in tears and lighting wired in 25mm lol.

 

[Engineer54]

There Are diversity figures suggested in the Electicians design guide by the IET. It has paper mills, rolling mills ect. I'm not sure i would 100% go with it though!

It's a good job then, that the larger commercial and industrial installations aren't designed by electricians then!! lol!!

 

[Guest55]

It's a good job then, that the larger commercial and industrial installations aren't designed by electricians then!! lol!!

why are you saying we're not capable ?
i've just recieved the elec drawings for the next stage of the project im working on now , designed by some big shot consultancy - they're a load of pants , completely ignoring the concept of positioning db's at the geographical load centre to reduce final circuit lengths.
;-)

 

[Engineer54]

I'm not getting into an argument on this issue, because their is good and bad in most areas on the design side of things.. But generally speaking an electrician would not be capable on designing the complete electrical installations for a large commercial or industrial project, and would never be asked too either.

Having been in and experience of working in a design office, i can't tell you how often it is, that the Engineers are working initially without the full details, so will generally often submit a concept drawing as a 1st issue. The Resident Electrical Engineer, or manager will then conduct a design review, marking/clouding the drawings up, complete with comments and return to the designer. REV 1 will then become the first ''working/installation'' drawing... But due to continuous changes, the final ''As Builts'' could be up to REV 6, 7, 8!! i've known one drawing to have 19 revisions!! ...lol!!!

Design review is initially my biggest element of work on all my projects, and were talking about literary 100's if not thousands of drawings covering everything from basic final circuit layouts, ELV systems, mechanical plant and controls, to external/internal MV and LV main distribution...