Dual RCD CU?

[andy_spark]

It was probably a term devised by rcd & cu manufacturers in conjunction with the IEE to make the sparky spend more money on equipment to sell to the poor un-suspecting customer!!

 

[Andy™]

thought that was the entire reason behind 7671?

 

[martinxxxxxx]

I would normally advise that RCBOs are fitted to the lighting circuits. But then I deal with a lot of student houses and while some may see this advice as a way of me generating work for myself. I justify it by my risk assessment of the normal users of the houses (ie daft hard drinking students). I am upfront that the regs don't require the work but normally landlords go for it. I do the same if other circuits such as showers have been added.

I see a lot of split boards, I never fit unless specified to do so the so called 17th ed boards as I see them as a cop out. Instead I follow the spirit as well as the letter of the regs and fit all RCBO boards. I compete with others fitting 17th boards on price as I am not greedy and am prepared to give the customer the best solution rather than me the greatest profit

 

[Zeespark]

RCBO's are fine for TN installs Martin but not TT, something to do with DP apparently, there is a thread on this.

AndyGuinness

 

[M107]

DP RCBO's are not required on a TT install......but as we decided at the time it is each to his own as to DP or not.

Covered back in May mate....http://www.talk.electricianforum.co.uk/your-pictures/14897-todays-work-3.html

 

[Zeespark]

I sincerely apologise M, I was just bringing up things that may come to bear on RCBO installs is all.

AndyGuinness

 

[batty]

Certain TT installation do require DP Rcbo protection ie caravan sites and jetties though.

 

[Sidewinder]

Amongst others Batty, but in general not domestic dwellings at this stage.

 

[steptoe]

I would still 'unsatisfactory' a TT with only SP protection.

I know others may well disagree with me, but,

thats just the way I see it.

 

[Sidewinder]

Steps,

We've been through this mate you have not convinced me sorry.

I have posted all the regs and their cross references and at the moment, right or wrong on a "normal" domestic TT install there is no requirement for double pole RCBO's.

This is as per the link in M107's post above.

 

[steptoe]

Canoeboy,

this is a VERY GREY area,

as discussed previously,

SW is of the opinion that they are not required as there is no reg stating they are,

I am of the opinion they are required as there is no reg stating they are not

read and interpet the reg however you feel you can win the argument against the coroner is MHO

 

[Sidewinder]

Steps,

The thing is IF you have complied with 7671, then it is EXTREMELY doubtful that you would ever end up in front of the coroner as you have a robust defence already provided and endorsed by HSE & the LA's, i.e. 7671!

I do understand where you are coming from, and I agree with you, totally!

My disagreement comes from the requirement to comply with 7671, you cannot "fail" an install on personal opinion on a PIR, I wish we could.

If you put an observation on a PIR you must be able to back that up with a Reg. No. which gives the non compliance and, I have not been able to find "that" reg. no.

To have an issue with a single pole solid neutral RCBO even on a TT would require more than 1 fault/defect, does 7671 allow for multiple simultaneous faults each of which creates a cascade effect to a more dangerous situation...

---------- Post Auto-Merged at 22:45 ---------- Previous post was made at 22:44 ----------

Canoe,

Shame I'm not with ELECSA as I would have turned the inspector grey!

 

[batty]

Amongst others Batty, but in general not domestic dwellings at this stage.

Just stating this for the learners on the forum.

 

[steptoe]

Steps,The thing is IF you have complied with 7671, then it is EXTREMELY doubtful that you would ever end up in front of the coroner as you have a robust defence already provided and endorsed by HSE & the LA's, i.e. 7671!

I do understand where you are coming from, and I agree with you, totally!

My disagreement comes from the requirement to comply with 7671, you cannot "fail" an install on personal opinion on a PIR, I wish we could.

If you put an observation on a PIR you must be able to back that up with a Reg. No. which gives the non compliance and, I have not been able to find "that" reg. no.

To have an issue with a single pole solid neutral RCBO even on a TT would require more than 1 fault/defect, does 7671 allow for multiple simultaneous faults each of which creates a cascade effect to a more dangerous situation...

---------- Post Auto-Merged at 22:45 ---------- Previous post was made at 22:44 ----------

Canoe,

Shame I'm not with ELECSA as I would have turned the inspector grey!

sometime, when I get a chance, (and I dont know just when ATM), although I have a load of other stuff going on just now,

Im going to sit down with the comic a try and make a reasoned argument with regs for why DP are deemed necessary protection on a domestic TT,

I know where you are coming from on the PIR as regards a personal opinion,

but I dont feel it is an opinion, more an interpetation, as is too much of 7671 left to.

 

[Zeespark]

What can of worms have I reopened here? :C ? :| :coat :innocent

AndyGuinness

 

[Theorysparky]

go and stand in the corner Zee.

good stuff though.....i dont do much TT

......

 

[tonyyoung]

Or the new fangled word for energising RCD protected circuits without prior testing for any shared neutrals or low insulation resistances due to damaged cables. Nuisance tripping would be a faulty oversensitive RCD, which should be easily rectified by replacing the faulty RCD, after checking all the standard operating trip times and preferable with a ramp test as well. Doc H

Ok forgive my use of the phrase nuisance tripping ! i just imagined water had gotten into my system somehow and the blasted RCD had tripped. If i were on holiday that would be a nuisance . lol

 

[steptoe]

the easy one is the disconnection of live conductors for isolation/maintenance, without causing inconvenience.

TT requires all LIVE conductors to be disconnected, so turning off a SP device isnt adequate,

IMHO this also blends into isolation under fault conditions, both LIVE conductors should be isolated.

 

[wozz]

You wont find a reg for or against, no where it says you must have DP fault protection, therefore SP complies.

I have never seen a reg saying disconnection of live conductors without causing inconvenience.

SP fault protection, DP isolation, they dont have to be the same device.

 

[Sidewinder]

If you search out there is a thread that I wrote all the regs up on, both M107 & myself went through the regs and drilled down through all the cross references.

I can't remember when, and I never seem to find anything with the search function.