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After a New Consumer Unit, now I need EICR & 100A DP Isolation Switch

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Trying to organise a CU replacement at home. It's a 1930s property. It's got a 10way CU but with no RCD protection.

Was after a larger unit with full RCBOs. Every Sparky I've spoken to has varied in their suggested plans.

1) Some say do an EICR first, others happy to just go straight with a new CU. EICR seems to add a big upfront cost.
2) Some mention DP RCBO, others don't.
3) One said for Building control notification, I've have to check the date on your smoke/heat & carbon monoxide alarm (?).
4) One said gas/water pipe bonding would be required and it's extra
5) One said, I'd have to get an isolator switch fitted by my supplier before the CU can be replaced. Currently there is only a mains fuse for isolation. The CU and mains fuse are both next to each other.

Prices vary for 1, 2, 3 significantly, I mean the most expensive quote is literally double the cheapest quote!

Any advice would be appreciated as this is driving me nuts!
 
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mainline said:
A dual CU with a pair of rcds and sp rcbos would be compliant.

The use of Dp rcbos is still not a requirement, you can't call it a requirement or say it's needed if there are other ways of doing things.
Click to expand...

There's a strong argument against this position from the perspective of potential nusiance tripping. It's one of those areas I'd raised where regs can be considered open to interpretation. I'd be happy to defend my position and I'm sure you'd be happy to do the same. Where our positions differ is that you'd likely be happy to install DP RCBOs at the insistance of a client, whereas I might refuse to install a dual RCD board if I felt there was good reason to do so.
 
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nicebutdim said:
There's a strong argument against this position from the perspective of potential nusiance tripping. It's one of those areas I'd raised where regs can be considered open to interpretation. I'd be happy to defend my position and I'm sure you'd be happy to do the same. Where our positions differ is that you'd likely be happy to install DP RCBOs at the insistance of a client, whereas I might refuse to install a dual RCD board if I felt there was good reason to do so.
Click to expand...

I haven't fitted a dual rcd board for many years and am not likely to do so :)

I always fit dp rcbos :)
But I'm not required to do so :)
 
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mainline said:
I haven't fitted a dual rcd board for many years and am not likely to do so :)

I always fit dp rcbos :)
But I'm not required to do so :)
Click to expand...

You're not required to do so in the circumstances in which you fit them or you believe there's no circumstance in which they need to be fitted?


My limited experience has already involved a couple of faults in which N-E issues caused subsequent problems on other circuits. I like the idea of knowing a future problem should be isolated with the circuit on which it occurred, thus further avoiding the possibility of nuisance tripping.

Most customers have the means to cover an additional few % on the overall job cost and also have the ability to understand a basic explanation for those costs. Customers who have to shave every penny from a job often aren't going to like my proposals anyway (and I'll seek to avoid them) and for customers who are of limited means I'll obviously aim to find a sensible accomodation that involves keeping costs low, while incorporating as much future convenience as possible.

No customer is ever going to thank me for the power not going off on more circuits than necessary, but I'm content knowing my ears won't burn too much if only one circuit goes off.
 
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As this is in danger of going round in circles I will finish up. The usual and preferred arrangement with a small tt installation is a 100ma or above S type rcd main switch and rcbo's. With this arrangement dp rcbo's are effectively a requirement IMO . Other arrangements may be devised,as above,in which dp rcbo's would not be a requirement. ( A dual rcd board AND rcbo's..🥺.).Remember....main bonding is a requirement....except when it isnt.
 
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OLDBOY said:
As this is in danger of going round in circles I will finish up. The usual and preferred arrangement with a small tt installation is a 100ma or above S type rcd main switch and rcbo's. With this arrangement dp rcbo's are effectively a requirement IMO . Other arrangements may be devised,as above,in which dp rcbo's would not be a requirement. ( A dual rcd board AND rcbo's..🥺.).Remember....main bonding is a requirement....except when it isnt.
Click to expand...
Why would you have an rcd main switch with a full dp rcbo board ?
 
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Not a main switch in a db, I use a separate RCD main switch which provides back up fault protection in case of rcbo failure, and protects the metal frame of the db rather than relying solely on mechanical protection to the tails.
 
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OLDBOY said:
Not a main switch in a db, I use a separate RCD main switch which provides back up fault protection in case of rcbo failure, and protects the metal frame of the db rather than relying solely on mechanical protection to the tails.
Click to expand...
If the db isn’t remote from the cut out and tails are properly installed a main switch with dp rcbos is compliant adding an upfront rcd is going to reduce selectivity
 
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mainline said:
If the db isn’t remote from the cut out and tails are properly installed a main switch with dp rcbos is compliant adding an upfront rcd is going to reduce selectivity
Click to expand...
In that instance sp rcbo's would be compliant. I have never said otherwise, and I have always stated an s type rcd main switch which will give selectivity. But many, myself included prefer to have the added insurance of an up front(s type) rcd on a tt, and in that case dp rcbo's are required. I have never stated that is the only option.
 
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OLDBOY said:
Not a main switch in a db, I use a separate RCD main switch which provides back up fault protection in case of rcbo failure, and protects the metal frame of the db rather than relying solely on mechanical protection to the tails.
Click to expand...
If the db isn’t remote from the cut out and are properly installed a main switch and dp rcbos is compliant
OLDBOY said:
In that instance sp rcbo's would be compliant. I have never said otherwise, and I have always stated an s type rcd main switch which will give selectivity. But many, myself included prefer to have the added insurance of an up front(s type) rcd on a tt, and in that case dp rcbo's are required. I have never stated that is the only option.
Click to expand...
sp rcbos on a tt with a main switch would have no selectivity with a N to E fault.

I think the issue is making a statement saying Required or Needed means that there are no other options.
 
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OLDBOY said:
In that instance sp rcbo's would be compliant. I have never said otherwise, and I have always stated an s type rcd main switch which will give selectivity. But many, myself included prefer to have the added insurance of an up front(s type) rcd on a tt, and in that case dp rcbo's are required. I have never stated that is the only option.
Click to expand...
You just said it again “ dp rcbos are required”.

Dp rcbos are not a requirement they are an option.
 
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I think you are rather mis-interpreting. I have only ever stated that where an upstream s type rcd is used in front of a db with rcbo's single pole rcbo's would not be compliant and therefore by default are required in that situation.I stand by that.
 
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OLDBOY said:
I think you are rather mis-interpreting. I have only ever stated that where an upstream s type rcd is used in front of a db with rcbo's single pole rcbo's would not be compliant and therefore by default are required in that situation.I stand by that.
Click to expand...
Look at the definition of Required.

Your post @ 34 says sp rcbo with main switch would be compliant?
 
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A main switch....not an rcd main switch. A db with a main switch and sp rcbo's would be compliant. It is not the way i would do it though.
Add a s type rcd main switch and the sp rcbo's are no longer compliant.
 
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OLDBOY said:
A main switch....not an rcd main switch. A db with a main switch and sp rcbo's would be compliant. It is not the way i would do it though.
Add a s type rcd main switch and the sp rcbo's are no longer compliant.
Click to expand...
I wouldn’t add an upfront rcd at all

Dp rcbos with main switch would be much better although not a requirement 🙄
The use of an upfront rcd should be avoided if possible.
 
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And - just to throw a spanner in the works!

Regulation 411.5.2 (Just refreshing memory on TT systems) states;
One of the following i) RCD OR ii) Overcurrent Protective Device shall be used, with;

Note 1 "An appropriate overcurrent protective device device may be used for fault protection provided a suitably low value of Zs is permanently and reliably assured."

Now we know in the real world a 'permanently and reliably low value of Zs' is unlikely, but hyperthetically, installing a RCD is not necessarily a god given!
 
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DefyG said:
And - just to throw a spanner in the works!

Regulation 411.5.2 (Just refreshing memory on TT systems) states;
One of the following i) RCD OR ii) Overcurrent Protective Device shall be used, with;

Note 1 "An appropriate overcurrent protective device device may be used for fault protection provided a suitably low value of Zs is permanently and reliably assured."

Now we know in the real world a 'permanently and reliably low value of Zs' is unlikely, but hyperthetically, installing a RCD is not necessarily a god given!
Click to expand...
Irrelevant.
All I have stated is that where an up front rcd is used sp rcbo's would not be compliant. I have not suggested any of the above is required, only the requirements where they are used.
 
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OLDBOY said:
In that instance sp rcbo's would be compliant. I have never said otherwise, and I have always stated an s type rcd main switch which will give selectivity. But many, myself included prefer to have the added insurance of an up front(s type) rcd on a tt, and in that case dp rcbo's are required. I have never stated that is the only option.
Click to expand...
If something is REQUIRED then that would mean that you MUST use DP rcbos when using an up front rcd, but that's not the case as there are other options to having to use dp rcbos.

Meaning that it's not a requirement.
 
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[ElectriciansForums.net] After a New Consumer Unit, now I need EICR & 100A DP Isolation Switch
 
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mainline said:
If something is REQUIRED then that would mean that you MUST use DP rcbos when using an up front rcd, but that's not the case as there are other options to having to use dp rcbos.

Meaning that it's not a requirement.
Click to expand...
I have never stated dp rcbo's MUST be used where an upfront rcd is in service, if you read back through my posts I clearly agree other options are compliant such as a dual rcd board.
What I do state (very clearly I believe) and stand by is that wherre rcbo's ARE used......they must be dp where there is a upstream s type rcd and in that arrangement are effectively a requirement, you seem incapable of understanding that I am only refering to where rcbo's ARE used. I believe i have been quite clear that with other arrangements sp rcbo's are compliant.
Perhaps you would be good enough Mainline to answer this.

Lets say you have a job where the designer has specified DB's with rcbo protection to all final circuits. A main switch of s type rcd is also specified. Its a TT earthing system.
Would you install sp rcbo's and provide an EIC on completion?
 
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