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

[suffolkspark]

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!

1 yes on a property of that age i would 100% want to do an eicr first, it helps to manage cost expectations because there are most likely other areas which would benefit from upgrading, you may even have rubber cables, or at the least un earthed lighting circuits.

2 dp not required if its just a normal board and nothing to think about with selectivity on sub mains etc

3 yes a consumer unit change is notified to building control, usually by the electrician so make sure you get one thst can and is on the competant person register

4 gas and water does usually require bonding unless it enters the property as plastic, some qwerks here so electrician will advise during eicr

5 yes your supplier should come and fit you an isolator so the electrician can safely perform the consumer unit upgrade, but you can get the EICR done before this.

 

[mainline]

It only becomes necessary if there is an up-front delay RCD, then you need downstream ones to be DP switching or you have no selectivity on N-E faults. Typically that would be a more complicated TT set-up (e.g. main/sub-DB, armoured cable from cutout to CU so needs RCD protection for ADS, etc).

Given many of the cost-effective compact RCBO are now DP (e.g. Wylex/Crabtree, Fusebox) its not such a big deal.

An upstream s-type rcd can still trip in certain circumstances, so still doesn't give 100% selectivity.

The real point being that it's not a requirement to have DP rcbo.

 

[OLDBOY]

There is no requirement for a TT installation to have double pole circuit protection.

An upstream s-type rcd can still trip in certain circumstances, so still doesn't give 100% selectivity.

The real point being that it's not a requirement to have DP rcbo.

It is indirectly, there is a requirement for a single fault not to result in entire installation loss, therefore a tt installation with an upfront rcd would not be compliant where sp rcbo devices were used

 

[HappyHippyDad]

As you can see from the replies @i3_happy all of your electricians were right and all of them were wrong

 

[HappyHippyDad]

My thoughts for what they are worth..

1. Not always essential, but sometimes a good idea. Sometimes essential.
2. Not required as you will have a DP main switch.
3. Don't really understand this point. The electrician really needs to be registered and therefore they will notify the CU change to the building authorities. Smoke detectors are not involved here.
4. If there is no Main bonding in place then it is extremely likely you need it on the gas and 50/50 on the water (depending on if there is a blue plastic pipe entering the house from the ground).
5. I suppose so, but not many of us would insist on that. I can't argue with the electrician who said that though, as they are being professional and do not want to illegally remove the main fuse.

 

[i3_happy]

Thanks all for the advice and varying perpectives. So, bottom line is that none of this is really clearcut, but open to interpretation.

Given the various opinions and info, I've taken another look at all this....

1) EICR - seems the way to go, but a valid point that if a lot of testing is done upfront then the CU replacement costs shoiuld be lower.

2) DP RCBO - actually the DP & SP are not too different in price, so why not go with DP, besides I have an electic car charger and would need a DP RCBO for that, I believe.

3) Smoke/Heat alarms - on the positive side it got me to check the dates on my alarms and just added a Heat alarm to the kitchen.

4) No earth bonding to Gas currently. The Water Supply pipe is the blue plastic for the incoming mains, so gathering that means no earth bonding required for the water.

5) For the iolator switch the DNO was not interested unless it was to be installed prior to the main fuse, however, British Gas surprised me by saying they could do it for £109 + tails cost extra. Will determine if the isolator will go between the fuse and meter or between the meter and CU. Given it's a smart meter probably the latter.

 

[HappyHippyDad]

Thanks all for the advice and varying perpectives. So, bottom line is that none of this is really clearcut, but open to interpretation.

Given the various opinions and info, I've taken another look at all this....

1) EICR - seems the way to go, but a valid point that if a lot of testing is done upfront then the CU replacement costs shoiuld be lower.

2) DP RCBO - actually the DP & SP are not too different in price, so why not go with DP, besides I have an electic car charger and would need a DP RCBO for that, I believe.

3) Smoke/Heat alarms - on the positive side it got me to check the dates on my alarms and just added a Heat alarm to the kitchen.

4) No earth bonding to Gas currently. The Water Supply pipe is the blue plastic for the incoming mains, so gathering that means no earth bonding required for the water.

5) For the iolator switch the DNO was not interested unless it was to be installed prior to the main fuse, however, British Gas surprised me by saying they could do it for £109 + tails cost extra. Will determine if the isolator will go between the fuse and meter or between the meter and CU. Given it's a smart meter probably the latter.

Excellent update, thanks. We like clear, well written updates

 

[mainline]

It is indirectly, there is a requirement for a single fault not to result in entire installation loss, therefore a tt installation with an upfront rcd would not be compliant where sp rcbo devices were used

My point is that using dp rcbos with upfront
s type rcd still wouldn’t give 100% selectivity.

 

[OLDBOY]

My point is that using dp rcbos with upfront
s type rcd still wouldn’t give 100% selectivity.

Agreed.
But people tend to look for a specfic regulation for a particular scenario. There is no specific regulation stating that a dp protective device is required for a tt with an upstream s type rcd. But nevertheless an sp device would not be compliant.

 

[davesparks]

My point is that using dp rcbos with upfront
s type rcd still wouldn’t give 100% selectivity.

Not 100% selectivity no, but better than with SP.
Also DP or SPSN RCBOs would allow the upstream RCD to be reset after it trips on a N-E fault whereas with SP RCBOs you could be stuck with the whole installation being off.