Does this comply with 314?

[Octopus]

As already stated it's a non issue.
If the end user loses the loft conversion electrics he can run a lead from elsewhere until it's fixed. If it's just nuisance tripped then the rest of the house is still on so he can see to reset.

I disagree .........IMHO the designer of the loft conversion circuits has failed to comply with the regs......

 

[Octopus]

How much of the 45k, did the Electrician see though?

At a guess, maybe around £900

 

[Midwest]

As already stated it's a non issue.
If the end user loses the loft conversion electrics he can run a lead from elsewhere until it's fixed. If it's just nuisance tripped then the rest of the house is still on so he can see to reset.

Not easily done in the middle of the night, or if your elderly or infirmed or just a little bit squiffy. Not really a good design, if you have to faff around with extension leads (not everyone has one), when a couple of RCBO's is a simple but easy fix?

 

[Deleted member 9648]

You are of course entitled to take that view.....but really your objection makes no sense. If it was installed on 2x RCBO's and the lighting one tripped during the night, and your elderly /infirm/squiffy type does not have a light plugged in or cant reach it then your RCBO has not improved their safety one bit.....Of course RCBO's are always preferable but to suggest this is non compliant with just two circuits on a separate RCD and the rest of the house unaffected is incorrect IMO.
A job I did last week involved 4 new circuits for kitchen equipment which I supplied from a 4 way DB with an RCD main switch, the rest of the existing installation is split over two RCD's on the existing DB. I have an NICEIC visit next month and he'll probably see this job. I'll let you know if he pulls it up as non compliant.

 

[Midwest]

You are of course entitled to take that view.....but really your objection makes no sense. If it was installed on 2x RCBO's and the lighting one tripped during the night, and your elderly /infirm/squiffy type does not have a light plugged in or cant reach it then your RCBO has not improved their safety one bit.....Of course RCBO's are always preferable but to suggest this is non compliant with just two circuits on a separate RCD and the rest of the house unaffected is incorrect IMO.
A job I did last week involved 4 new circuits for kitchen equipment which I supplied from a 4 way DB with an RCD main switch, the rest of the existing installation is split over two RCD's on the existing DB. I have an NICEIC visit next month and he'll probably see this job. I'll let you know if he pulls it up as non compliant.

Well, I seem to recall someone on this forum arguing that a dual RCD set up, was non compliance with 314. I think that's a bit extreme. What someone does with an installation after you've installed it, you have no control over. But in the example given here, at least having two separate RCBO's would give some scope.

In the example you've given, a loss of complete power to a kitchen, is unlikely to cause danger as suggested in 314, although it may well cause inconvenience. However, the control of both lighting & power for a bedroom at night by one RCD, could cause danger, dependant on the end user (when I designed this, did I do all that was reasonably practicable).

You may be aware that the draft for the 18th, will make more demand of the designer to consider unwanted tripping, (proposed) reg 531.3.2. Limiting down stream current to 30% of the RCD rating. So perhaps you kitchen design may not comply with the 18th?

 

[Deleted member 26818]

Assuming it's a new build, it complies.
Could have been done better.

 

[Octopus]

Assuming it's a new build, it complies.
Could have been done better.

Not a new build. Loft conversion

 

[Deleted member 26818]

New build as in new room in the loft.
Or are you saying the loft was already converted?

 

[Deleted member 9648]

Well, I seem to recall someone on this forum arguing that a dual RCD set up, was non compliance with 314. I think that's a bit extreme. What someone does with an installation after you've installed it, you have no control over. But in the example given here, at least having two separate RCBO's would give some scope.

In the example you've given, a loss of complete power to a kitchen, is unlikely to cause danger as suggested in 314, although it may well cause inconvenience. However, the control of both lighting & power for a bedroom at night by one RCD, could cause danger, dependant on the end user (when I designed this, did I do all that was reasonably practicable).

You may be aware that the draft for the 18th, will make more demand of the designer to consider unwanted tripping, (proposed) reg 531.3.2. Limiting down stream current to 30% of the RCD rating. So perhaps you kitchen design may not comply with the 18th?

I am not aware of those proposals, are you saying it is proposed that a 63a RCD would be restricted to a load of 21a?.....then presumably a 32a RCBO would be restricted to under 11a?
So a 10kw shower would need a minimum 135a RCBO ?....Sorry if I'm having a blonde moment but that just doesn't make any sense.

 

[westward10]

Not sure if this will be legible but here it what it states.

 

[Rpa07]

That's surely relating to the residual earth leakage current, no? So they are saying that if you have appliances that have a heavy leakage then a 100ma RCD will have to be provided up from 30ma or division of leakages attempted?

 

[westward10]

Correct, the accumulated leakage of upstream circuit/s from an rcd should not exceed 30% of the rcds rated residual current. So for an rcbo it applies to the connected circuit, for a dual rcd board the accumulated conductor current and/or leakage applies to the sum of circuits protected by each rcd. So for 30ma that is 9ma if my math is correct.

 

[Rpa07]

I sense RCBOs in all our futures - @Murdoch is like a prophet, like!

 

[Midwest]

That's surely relating to the residual earth leakage current, no? So they are saying that if you have appliances that have a heavy leakage then a 100ma RCD will have to be provided up from 30ma or division of leakages attempted?

Nope, I think the suggestion is the designer must divide the circuits across RCD's, so that any anticipated earth leakage would be limited to 30% of the tripping current for the RCD, i.e. 10mA for 30mA RCD. So consideration of the appliances and loads connected to said RCD. Kitchen appliances and IT equipment come to mind.

Westy proceeds me. See why its important to read & comment on the draft. You've got 3 days left.

 

[Rpa07]

So RCBO boards would effectively negate leakage from other areas on other circuits -

Nope, I think the suggestion is the designer must divide the circuits across RCD's, so that any anticipated earth leakage would be limited to 30% of the tripping current for the RCD, i.e. 10mA for 30mA RCD. So consideration of the appliances and loads connected to said RCD. Kitchen appliances and IT equipment come to mind.

Westy proceeds me. See why its important to read & comment on the draft. You've got 3 days left.

Your kitchen leakage would be on that RCBO and your IT leakage on the downstairs ring or radial.

 

[westward10]

With rcbos you will not get accumulated currents from other circuits but rcbos are lawless things. It suggests correct division of circuits to avoid unwanted tripping so for example if you install a ring final circuit with ten points of utilization is there a likelihood accumulated leakage currents of connected appliances may cause unwanted tripping, if yes then two ring final circuits with five on each may be a better option.

 

[Deleted member 9648]

That makes more sense. It would not be an unreasonable proposal to design a low potential earth leakage into an RCD protected circuit.
Cue amended forms and earth leakage measurements on all RCD protected circuits.

 

[Rpa07]

Let's hope the prices of earth leakage clampmeters come down then - otherwise the results will be as fictional as the BS7671 is now!

 

[Midwest]

I clamped my own house the other day. PC running, few led lights on, tv on, appliance turned on but not running. Clamp meter's a cheap en, but I had 14mA leakage. But I've have that split across RCD & RCBO's. Went to a job in the afternoon, semi with 1 x lighting, 1 x RFC & electric cooker. 9mA eath leakage.

 

[Midwest]

That makes more sense. It would not be an unreasonable proposal to design a low potential earth leakage into an RCD protected circuit.
Cue amended forms and earth leakage measurements on all RCD protected circuits.

That's my pleasure, glad I've pointed it out to you