Discuss Max demand problem in the Periodic Inspection Reporting & Certification area at ElectriciansForums.net

Welcome to ElectriciansForums.net - The American Electrical Advice Forum
Head straight to the main forums to chat by click here:   American Electrical Advice Forum

J

jimzxcv

First post - be gentle.

Just changed a consumer unit and am struggling with the "max demand" bit on the paperwork. RCD is 100A, Main fuse is 100A, it has 2 showers (50 A each) no diversity allowed on showers. so, um, not much room for anything else. .....or am I being a moron?
Thanks
Jim
 
If your main fuse is 100amp, because it might just be the carrier rating, not the fuse inside, then that is what I would put on the certificate

Did a nice DNO chap come put and pull it for you and then look and tell what the fuse was because it might have been an 80amp or even a 60amp, but whatever it was that is what you put down ...........................
 
Thanks, but as I am a newbie I was going through the books to get it all right and the NICEIC book says this is the bit where you add up all the demand , do your diversity calcs and end up with the max demand; which sounds like a hideous amount of sums.
Is it this or do you just go for the main fuse rating??
 
Do you have a copy of the OSG by any chance?

Well if you do have a look at page 157 and you will see a completed EIC and you will see they have put put as maximum demand 60amps, which is remarkable similar to standard ratings of fuses you will get in a domestic head ........60 80 or 100amp

Then go to page 159 and you will see the SoTR and the circuits that were rewired and you work out and tell me with diversity what the laod is, I bet you a bottom dollar it will not be exactly 60amps.

Also have a read of section 311 in the regsa, and you will see that they mention diversity and "May be used"

As you progress in this industry you will come to see that the NICEIC seem hell bent in re-writing the regulations as per their take on them, and sometimes they get it right and sometimes they don't You maximum demand is the maximum size of the DNO fuse, you can't exceed that can you, if you put another 30 showers in and put the load up to 400 amps then the fuse will blow., and you have exceeded the maximum load or demand
 
Must admit that in this situation, very often I put on as much load as possible and measure the load at the supply after the EICR or cu change. This very often gives a lower value than the fuse rating.
What Malcolm says makes great sense but I struggle with inserting what is in effect the protective device characteristics for maximum demand. Though I could very well be wrong.
 
Ok get your point Murdoch but am I right can you not add the breakers up on a domestic consumer and use that value

Personally I think the "diversity and max load" calculations need a rethink.

40 years ago houses had 4 or 5 circuits. Now they have 10 plus - more for convinience - yes, we have more plugged in, but most "stuff" isn't energy hungry, unlike 40 years ago when many people used plug in electric heaters. 11KW showers do make a difference!
 
i thought so aswell malc taking things off but it is gone ive got an eic and eicr in front of me and it is most definitely gone.

farmer - i suppose its purely down to the reason of this OP to much discrepency theyve also added IT system to the type of earthing arrangement section
ill scan it in and post it up
 
Are they allowed to? I thought it was ok for a scheme to design their own cets, but it had to based on the ones in the Regs, and so they could put extras onto it, but omit things

But Malcolm, I thought that the NICEIC was god of the rules these days.... lol
 
Let's face it, how many times do 2 showers run at the same time? It's bad enough having 1 running and then flushing the loo!
Agree that the whole MD thing needs a rethink. For what it's worth, I always put the fuse rating on a CU change. The point of MD calculations is when you are designing a new system.
 
Last edited:
i thought so aswell malc taking things off but it is gone ive got an eic and eicr in front of me and it is most definitely gone.

farmer - i suppose its purely down to the reason of this OP to much discrepency theyve also added IT system to the type of earthing arrangement section
ill scan it in and post it up


:whatchutalkingabout.......................... IT now that is going to throw the cat among the pigeons

Can see it now ........................

" Just be asked to change the CU for a customer and there is this head that I've never seen before, it seems to have no fuse but there is a box with the cables going into it, a bit of electronics and a light with a buzzer attached............... and every time I do a Ze on it.....sets the light and buzzer off .......is it a ..............."
 

Reply to Max demand problem in the Periodic Inspection Reporting & Certification area at ElectriciansForums.net

OFFICIAL SPONSORS

Electrical Goods - Electrical Tools - Brand Names Electrician Courses Green Electrical Goods PCB Way Electrical Goods - Electrical Tools - Brand Names Pushfit Wire Connectors Electric Underfloor Heating Electrician Courses
These Official Forum Sponsors May Provide Discounts to Regular Forum Members - If you would like to sponsor us then CLICK HERE and post a thread with who you are, and we'll send you some stats etc
This website was designed, optimised and is hosted by Untold Media. Operating under the name Untold Media since 2001.
Back
Top
AdBlock Detected

We get it, advertisements are annoying!

Sure, ad-blocking software does a great job at blocking ads, but it also blocks useful features of our website. For the best site experience please disable your AdBlocker.

I've Disabled AdBlock