RCBO query

[pete01]

No not really.
Our basic design (with fuses) would be to allow a 13% overload and not trip. A 45% overload must trip. Anything in between then it depends. Please note it does not mean will trip instantly or near instantly, but "within the conventional time" (which is often 2 hours but could be 4 hours.
Follow the curves on a MCB and you will find more info on that particular MCB rating, you might be surprised.
I would never advise running anything over 32A on a 32A MCB as you will be running it on its curve - a big no.
Select your MCB (or RCBO) according to the cable rating max and your design current max and breach neither.

Thanks, I dont really know how it's got to this anyway , the thread was about a 40 amp rcbo on 5m of 6mm which is fine.

 

[morqthana]

Stop jabbering

I really refuse to put up with this.

I refuse to put up with people posting insults and abuse and then be the one criticised for doing things to spoil threads.

I refuse to put up with being told I'm jabbering for daring to ask someone why he agreed with someone else saying I was.

And why should I have to put up with it? Why should anybody have to put up with being treated like that?

So come on, Pete - using the dictionary definition of jabber, and fairly and rationally analysing what I wrote, show how that it was reasonable to call it jabbering?

 

[pete01]

I really refuse to put up with this.

I refuse to put up with people posting insults and abuse and then be the one criticised for doing things to spoil threads.

I refuse to put up with being told I'm jabbering for daring to ask someone why he agreed with someone else saying I was.

And why should I have to put up with it? Why should anybody have to put up with being treated like that?

So come on, Pete - using the dictionary definition of jabber, and fairly and rationally analysing what I wrote, show how that it was reasonable to call it jabbering?

Im just joking mate... I mean no offence

 

[morqthana]

Don't bring me into your row, all I did was agree with someone who knows what he's talking about.

What you did was to agree with someone who said that I was jabbering when I wrote this:

As in a time you'd more likely state in minutes than fractions of an hour? Yes.

As in only a few minutes? No.

So unless you're in the habit of thanking and liking posts with which you disagree, then please show how what I wrote was unintelligible, gibberish, or nonsense.

And if you don't think it was, what motivated you to like a post saying it was?

 

[morqthana]

Thanks, I dont really know how it's got to this anyway , the thread was about a 40 amp rcbo on 5m of 6mm which is fine.

It got to that because the thread was also about

If the 6mm cable's to remain in-situ, do you agree re dropping to 32A RCBO?

I would like to know if it's advisable to have the 32A RCBO fitted or just leave the 40A?

Which is why a discussion of a 40A shower on a 32A RCBO arose.

 

[pete01]

It got to that because the thread was also about




Which is why a discussion of a 40A shower on a 32A RCBO arose.

Im sure I said ages ago a 6mm on a 40 amp is fine.

 

[morqthana]

Im sure I said ages ago a 6mm on a 40 amp is fine.

You did.

And that's what the OP has, but he's also had an electrician say it should be a 32A, and in his opening question he asked "If the 6mm cable's to remain in-situ, do you agree re dropping to 32A RCBO?", and then asked again a few posts later.

 

[pete01]

You did.

And that's what the OP has, but he's also had an electrician say it should be a 32A, and in his opening question he asked "If the 6mm cable's to remain in-situ, do you agree re dropping to 32A RCBO?", and then asked again a few posts later.

So what's your answer?

 

[Harry Bloomfield]

I would never advise running anything over 32A on a 32A MCB as you will be running it on its curve - a big no.

Why?

On a cooker circuit, you allow for diversity, where you make an assumption that not all of the cooker/hob will be turned on at the same time, or it will not be all on for long.

A form of diversity, is applied to your cut-out main fuse - turn everything on, and you will exceed the 60 or even the 100amp fuse, at least for a while.

An electric shower, by their nature, and the sheer cost of running one, is not something most people will run for more than a few minutes. If it were accidentally left on for an extended period, then I for one, would appreciate a 32amp MCB eventually tripping, to shut it off.

 

[SUNRAY]

Genuinely interested in how this would work.

I presume that by "heater", you are referring to the element.

How did this caused overload manifest itself in these two quite different appliances?

A 2kw heater cant suddenly decide to be a 3kw.....can it?

Wire wound heater elements as used in fan heaters, tumble dryers etc can certainly distort and sections short out.

In the oven the 2 connexions were at the same end of the outer metalic sheath so I imagine a short formed within the enclosed element part way round.
In the shower heater I didn't get around to investigating much but at the time: One of the 3 elements was low resistanceend to end but the IR was ok. I haven't seen it for several years so sadly I think it must have gone for scrap.

EDIT: that reminds me, I thought I posted a pic of an over heated flex https://www.diynot.com/diy/threads/resistive-element-ocpd.578158/#post-5130268

 

[SUNRAY]

I requested:

But you had to, you just had to:

What you did was to agree with someone who said that I was jabbering when I wrote this:

Yes, for once you are correct.

View attachment 390375

So unless you're in the habit of thanking and liking posts with which you disagree, then please show how what I wrote was unintelligible, gibberish, or nonsense.

And if you don't think it was, what motivated you to like a post saying it was?

I agreed because in my opinion it's a valid question, as you have noticed there are 5 in that question. In case you haven't noticed that's 5 menmbers who are asking why you talk jibberish?

 

[SUNRAY]

I really refuse to put up with this.

Don't then - you don't have to.

I refuse to put up with people posting insults and abuse and then be the one criticised for doing things to spoil threads.

Don't then - you don't have to.

I refuse to put up with being told I'm jabbering for daring to ask someone why he agreed with someone else saying I was.

Don't then - you don't have to.

And why should I have to put up with it?

You don't have to

Why should anybody have to put up with being treated like that?

How many are?

So come on, Pete - using the dictionary definition of jabber, and fairly and rationally analysing what I wrote, show how that it was reasonable to call it jabbering?

Because - like you - he uses a dictionary then after that - unlike one member on here - fairly and rationally analysed what had been written and compared it with the dictionary definition.

 

[SUNRAY]

Quite simply, no one, but no one, will run a shower for in excess of one hour. In fact most will be in, and out within minutes - that is the point of a shower, speed for most people. The worst that can happen is that if you exceed the 'on time', is that the MCB/RCBO might eventually trip. Inconvenient, if you happen to still be in that shower, but perhaps a reminder to get out?

All MCB's/RCBO's, in the same range, are built with the very same internal components, able to carry the maximum current of the same range, all that varies is the sensing/trip components, suggesting that overheating due to overload, should not be an issue.

After decades of use of a our 9.5kw shower, supplied via a 32amp RCD, last year I decided it was time to upgrade our consumer unit with a larger item, including RCD's, and all new MCB's. Once that was done, out of curiosity, I took the opportunity to closely examine the old 32amp MCB, which had supplied our shower, and never once tripped. As expected, there was absolutely no sign of any wear, damage or any sort of issue at all.

I'll go further and say the same regarding the 10.5KW in my rental property. The only damage I found after correcting the circuit was some minor distortion of the 4mm² cable. I don't know which tenant changed the heater as the agent dealt with the last tenant change.

 

[morqthana]

I requested: View attachment 390389

Yes, you did, but that's a bit like punching someone and then "requesting" that they don't punch you back. It doesn't work like that.

You brought yourself into this row the moment you expressed agreement with Harry Bloomfield saying that I was "jabbering". It does work like that.

I agreed because in my opinion it's a valid question,

OK, so what, in your opinion, is wrong with what I wrote here:

The thing about a shower, is that they only run for a matter of minutes

As in a time you'd more likely state in minutes than fractions of an hour? Yes.

As in only a few minutes? No.

or here (which was another post where you agreed with Harry's categorisation of it as "jabbering"

You said "The thing about a shower, is that they only run for a matter of minutes."

I asked if you meant a time which would be stated in "minutes" rather than "hours" or fractions of hours, or if you meant just a few minutes.

If some examples would help, does your "matter of minutes" encompass, say, 20/35/50 minutes, or is it limited to 3/5/10. That sort of thing.

I didn't think it was that complicated.

which turns them into text which is unintelligible, gibberish, or nonsense?

as you have nociced there are 5 in that question. In case you haven't noticed that's 5 menmbers who are asking why you talk jibberish?

Indeed.

And I've asked them the same that I have asked you.

All of you are welcome, using commonly adopted standards of English comprehension, to show in what way these

• As in a time you'd more likely state in minutes than fractions of an hour? Yes.
  As in only a few minutes? No.
• You said "The thing about a shower, is that they only run for a matter of minutes."
  I asked if you meant a time which would be stated in "minutes" rather than "hours" or fractions of hours, or if you meant just a few minutes.
  If some examples would help, does your "matter of minutes" encompass, say, 20/35/50 minutes, or is it limited to 3/5/10. That sort of thing.
  I didn't think it was that complicated.

are gibberish, or unintelligible nonsense.

 

[morqthana]

Don't then - you don't have to.

I'm glad you agree.

Although that agreement appears to be at odds with your request in #58 and associated complaint in #71, which indicate that what you think is that when it is you dishing it out, putting up with it is exactly what you want me to do.

Because - like you - he uses a dictionary then after that - unlike one member on here - fairly and rationally analysed what had been written and compared it with the dictionary definition.

Do you think that's what he did? Do you think that he fairly and rationally analysed these:

• As in a time you'd more likely state in minutes than fractions of an hour? Yes.
  As in only a few minutes? No.
• You said "The thing about a shower, is that they only run for a matter of minutes."
  I asked if you meant a time which would be stated in "minutes" rather than "hours" or fractions of hours, or if you meant just a few minutes.
  If some examples would help, does your "matter of minutes" encompass, say, 20/35/50 minutes, or is it limited to 3/5/10. That sort of thing.
  I didn't think it was that complicated.

and decided that they were unintelligible, gibberish, or nonsense?

You agreed with Harry when he said they were, so clearly you think they are.

I await with interest your fair and rational analysis of my words which shows them to be unintelligible.