Workshop power

[DefyG]

But in any event if you use the correct value of U0 it is less than 2kW.

The 2kW is only a nominal value at a nominal voltage, quoted by manufacturers as with voltage fluctuations or volt drop the output power could be less but could also be more if manufacturers base it on a nominal 230v and actual is 234volts!

 

[Soi disant]

The 2kW is only a nominal value at a nominal voltage, quoted by manufacturers as with voltage fluctuations or volt drop the output power could be less but could also be more if manufacturers base it on a nominal 230v and actual is 234volts!

But it's always been that way for resistive loads - they are quoted at a particular voltage or voltage range.

The correct voltage to use in calculations is 230, so loads should be evaluated on the basis of what they are at that voltage.

new electric oven installed which is 240v 2075w.

So it should be viewed as 1906W.

I don't think you'd get many takers for the view that a 1700W appliance should be put on a dedicated circuit as it would be over 2kW at 253V.

 

[David Anthony]

Was planning to put a separate small consumer unit in the shed, but even so I think a separate feed is probably the only way to go. Just have to explain to the Mrs why I am knocking out the under stair area ?

Only thing you need to tell the missus is the microfangula is condified and her eyes will cross and she'll go away

 

[David Anthony]

Agree but many Electricians want the rules and regulations in black and white, it wouldn't be to much to ask to point this out to the less educated newbies amongst our community would it?, maybe those that think they know it all will disagree. What do you think? I'm not including you in the know it all statement by the way.

Some counties have Regs imbedded in the law and their Regs are very specific about compliance with prison sentences for when it goes wrong. I was working in one such country when I took their Regs course and we were told at the time there were 4000+ electricians facing prosecution.

 

[Soi disant]

In most cases, a 2kW+ fixed load shouldn't be connected to a RFC, but occasionally (e.g. very short duration load?) it may be acceptable.

Phew - I can carry on plugging my kettle, my tumble drier, my washing machine...

Although #2 on that list doesn't run for "very short" durations.

 

[Soi disant]

Agree but many Electricians want the rules and regulations in black and white,

Ah - but what's to be done when you show them black words on white paper and they can't tell the difference between "must" and "should", or "normative"and "informative"?

 

[David Anthony]

Ah - but what's to be done when you show them black words on white paper and they can't tell the difference between "must" and "should", or "normative"and "informative"?

Send them off to get a left hand screwdriver and a tin of current

 

[DefyG]

Send them off to get a left hand screwdriver and a tin of current

Dont jest, this website has 3922 of them apparently ?

 

[David Anthony]

Dont jest, this website has 3922 of them apparently ?

View attachment 84449

Found this

https://img1.accu.co.uk/news/Right-Hand-Left-Hand-Thread.jpg

 

[pc1966]

Found this

Or some cool, but slightly pointless, example of Russian engineering curiosity:

 

[pc1966]

I sometimes wonder why folks get so worked up about the "2kW fixed load" thing.

We all know the RFC is quite robust and tolerant of most things and many houses have (or had) practically everything bar the lights & cooker on a single RFC. Quite often folks would have a couple of 3kW heaters and the usual washing machine, tumble dryer, etc, in use and no problems.

Putting significantly more than 13A on at a point on the RFC is getting in to suspect territory as you can't be sure of how well the currents in the two "legs" are going to balance, but we have few loads that come in to that area. Probably just wired-in cookers, heating showers, or an EV charger in recent year or two, and they would normally be on separate radials anyway.

The only odd one I can think of is the old immersion heater, less popular these days due to combi boilers and instant-heat showers, as they would typically be around 3kW and could be heating for an hour or more easily. So were they the motivation for saying fixed loads above 2kW, and not the 3kW of a 13A socket?

Also the argument for putting something on to a separate circuit goes beyond the basic aspect of circuit protection alone, there is also the "good engineering" aspect of minimising inconvenience/risk under fault conditions to allow the fault to be isolated with the least collateral damage. I guess a number of "fixed loads" come in to this sort of territory, especially water heaters, where you would want to be able to keep any faults from taking out all/half of the house socket outlets as well.

 

[brianmoooore]

I sometimes wonder why folks get so worked up about the "2kW fixed load" thing.

Quite often folks would have a couple of 3kW heaters and the usual washing machine, tumble dryer, etc, in use and no problems.

This is exactly why! The above may well work on a single RFC with no problems in practice, but if there's a 2kW+ fixed load as well, that will likely take it over the edge.