Rcd vs distributors fuse

[telectrix]

praps he's got 2 mothers-in-law. :lol::21:

 

[Risteard]

Loading and diversity is part of regulations so you can't knock him for doing it by the book.

Figures quoted in the OSG are not part of the Regulations. Diversity requires an assessment of the load - there is absolutely and certainly no requirement to use the figures quoted in the OSG!

 

[DuncanS]

You need to do your maths again re the cooker as its wrong !

I challenge you on that, how is it wrong?

 

[Plonker 3]

Ok we've gone of subject a bit here I appreciate the diversity situation believe me, my question is not about diversity. I simply need to know if my sparky will need to upgrade my existing consumer unit from 80a RCD to a 100A rcd, bearing I mind uk network are upgrading their fuse to 100A because we are having a granny annex fitted with a shower and a cooker, uk network made the discussion to do this as when the annex is finished we will have 2 cookers, 3 showers, 3 ring final circuits which have significant demand due to the 2 living rooms with lots of gadgetry, a garage workshop, a summer House, we also have 3 lighting circuits, a jacuzzi and all manner of ponds and fish tanks all drawing a significant current most of the time.... Please enough about diversity.

and what readings did you get when you clamped the exiting installation?

 

[Risteard]

I simply need to know if my sparky will need to

Will he/she not know what he/she will need to do, or am I missing something?

 

[telectrix]

all your sparky will need to know is whether your good for the payment. he/she's been to college for 3 years so you don't need too worry about the technicalities. i managed to blow suppliers fuse with a new cooker and hob, but then again it was a 30A 3036, fitted in 1926.

 

[Risteard]

I challenge you on that, how is it wrong?

See post #16.

 

[DuncanS]

Oh but I can. Firstly, you never mentioned a socket outlet incorporated in the cooker switch!

Secondly, you never deducted the 10A before calculating 30% of the remainder. You just added it back on giving an excessively high figure!

Sorry mate but OSG doesn't say to do that, what it says 10a + 30% fl of connected appliances in excess of 10a + 5a if s/o is incorporated....

 

[DuncanS]

Oh but I can. Firstly, you never mentioned a socket outlet incorporated in the cooker switch!

Secondly, you never deducted the 10A before calculating 30% of the remainder. You just added it back on giving an excessively high figure!

But the on site guide doesn't say anything about 30% of the remainder it just says 10a +30% of full load + 5a if socket incorporated. I can read and here it is right in front of me Appendix A page 111.

 

[Risteard]

Sorry mate but OSG doesn't say to do that, what it says 10a + 30% fl of connected appliances in excess of 10a + 5a if s/o is incorporated....

Are you absolutely positive?

 

[KFH]

On my house I worked out diversity using the OSG at over 120A it has run successfully fo r > 30 years on a 60A fuse. This included a 9kW pool heater that was left on for long periods of time (Weeks unfortunately for my wallet) as well as 9kW shower, pond pumps, computers, the odd heater, oven, microwave, immersion heater and kettles.

If the 80A RCD has been working happily on a 60A supply fuse it will continue to do so quite happily on a 100A fuse as the load going through the RCD has not increased unless you change something.

Should you not be asking your electrician what he recommends and if you trust him/her taking thier advice. If you have worries get a clamp meter on the supply to see what you are actually using.

 

[DuncanS]

Are you absolutely positive?

Unless I've been stuck by selective blindness.... Check it out page 111

 

[Risteard]

Unless I've been stuck by selective blindness.... Check it out page 111

My OSG is nearly 100 miles away so I'm afraid I'll have to check later (or allow someone else to). Unless they have introduced an error in the most recent incarnation of it, however, I can assure you that it doesn't say that.

 

[GMES]

Page 110 osg household cooking appliances
1st 10amp of the rated current plus 30% of remainder plus 5% for socket outlet.

 

[Octopus]

Here is a little cunumdrum that is probably quite simple. Uk network are coming to upgrade their fuse from a 60A to a 100A so that we can put in another mini consumer unit for a new shower and cooker... The existing consumer unit which serves the house is protected by an 80A RCD with 30mA trip, my question is, should we replace the RCD with a 100A 30mA one or is it satisfactory as the load will be split once the mini consumer unit has been installed? My understanding is the existing RCD can only handle a load of 80A and if the distributors cut out is 100A then we run the risk of burning out the RCD.

So who is "we" then? I'm guessing that you are still sparking.

 

[Andy78]

Ok we've gone of subject a bit here I appreciate the diversity situation believe me, my question is not about diversity. I simply need to know if my sparky will need to upgrade my existing consumer unit from 80a RCD to a 100A rcd, bearing I mind uk network are upgrading their fuse to 100A because we are having a granny annex fitted with a shower and a cooker, uk network made the discussion to do this as when the annex is finished we will have 2 cookers, 3 showers, 3 ring final circuits which have significant demand due to the 2 living rooms with lots of gadgetry, a garage workshop, a summer House, we also have 3 lighting circuits, a jacuzzi and all manner of ponds and fish tanks all drawing a significant current most of the time.... Please enough about diversity.

Your thread 7 weeks ago quoting this exact situation made out you are using this job for your NAPIT assessment. Now you say you have a sparky in doing it for you. Which one is it ?

Also to get this element out of the way, table A1 on page 110 of the OSG says to use 10A + 30% of the remainder. Table A2 on page 111 of the OSG says 10A + 30% of full load.

 

[DuncanS]

Page 110 osg household cooking appliances
1st 10amp of the rated current plus 30% of remainder plus 5% for socket outlet.

I'm sorry but it just doesn't say that.... I tried to upload a picture of the page but Im not sure it worked. Here is the exact quote from the osg printed in 2013... "10a + 30% f.l. Of connected cooking appliances in excess of 10a + 5 a if socket-outlet is incorporated in control unit" I'm not sure how you guys interpret that as all the variations I've so far seen....

 

[Risteard]

in excess of 10a

And that, my friend, is where it says it. In excess of 10A means not including the first 10A.

 

[DuncanS]

And that, my friend, is where it says it. In excess of 10A means not including the first 10A.

No according to English in excess means, when more than, not not including.

 

[Risteard]

No according to English in excess means, when more than, not not including.

So what does 30% of the load exceeding 10A mean then? It means not including the 10A. The first 10A does not exceed 10A.