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

[i3_happy]

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!

 

[OLDBOY]

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.

 

[newfutile]

I guess your mean a s type (RCD) Residual Current Device in a tt system,otherwise there in no selectivity and little point in having rcbos,I have never had an rcbo fail only the rcds seem to fail for some strange reason

 

[mainline]

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.

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

 

[OLDBOY]

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

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.

 

[mainline]

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.

If the db isn’t remote from the cut out and are properly installed a main switch and dp rcbos is compliant

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.

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.

 

[mainline]

edited double sent

 

[mainline]

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.

You just said it again “ dp rcbos are required”.

Dp rcbos are not a requirement they are an option.

 

[OLDBOY]

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.

 

[mainline]

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.

Look at the definition of Required.

Your post @ 34 says sp rcbo with main switch would be compliant?

 

[OLDBOY]

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.

 

[mainline]

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.

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.

 

[DefyG]

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!

 

[OLDBOY]

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!

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.

 

[DefyG]

Its all totally irrelevant to the OP's original post!

 

[OLDBOY]

Its all totally irrelevant to the OP's original post!

True, so what was your thinking posting something totally irrelevant?