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!

 

[SJD]

Re (1), the testing for an EICR is pretty much the same testing you should do for a consumer unit change. So in theory you can have an EICR done, and the CU change costs should reflect that most of the testing has already been done. Many people would want to do the testing first on an old installation in case it throws up lots of unexpected and potentially costly issues.

Re (2), for a TT installation (earth rod rather than supplier earth), using DP RCBOs is essential, but the cost of them has come down now to not much more than single pole RCBOs that it might be simpler for someone to just stock the DP ones that suit all types of installation.

Re (3), that is nonsense, smoke or heat or CO alarms don't come into notifying a consumer unit change. You do need to make sure whoever does the work is registered and able to notify to BC via one of the schemes (NICEIC, ELECSA), otherwise it won't get done.

Re (4), the bonding must be checked and may need replacing or even adding if missing. That is likely obvious on a survey and can be included in a quote.

Re (5), some electricians would require this. Some DNOs are rather unhappy about a fuse being pulled, some are more enlightened.

 

[littlespark]

To answer some of those questions.

1) Before changing a CU, its good practice to at least perform a "mini" EICR, just to make sure there are no undetected faults which could trip a more sensitive RCBO. Borrowed neutrals on lighting circuits are a common thing. For a near 100 year old house, its wise to have one done, if its all original wiring, with possible DIY add-ons here, there and everywhere. It should be done as part of the board change price. There should be an installation certificate produced after the board change.

2) Manufacturers wouldn't make single pole RCBO's if they weren't permitted... so its down to the electrician... Some do, some don't specify double pole.

3) Its covered under Part P of building control.... but as i am Scottish, i dont have to worry about it, but one of my English colleagues will know more about it.
You can check the dates yourself.... Not the responsibility of the electrician... They can only advise.
Renewal of house insurance may be another matter though, if they are indeed out of date, or not enough of them.
You can contact building control yourself to see what is required.

4) Not necessarily. Many supply pipes and pipes within properties are plastic now, so it could be that earth bonding is only covering a metal stopcock and nothing else.

5) Yes. Electricians are not generally permitted to cut seals on supply fuses and pull them. (although some are)
An isolator fitted by the supplier allows anyone else to safely change the board by simple turning the isolator off.

 

[westward10]

Re (2), for a TT installation (earth rod rather than supplier earth), using DP RCBOs is essential, but the cost of them has come down now to not much more than single pole RCBOs that it might be simpler for someone to just stock the DP ones that suit all types of installation.

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

 

[DefyG]

2 replies and somewhat contradictory advice! the poor OP is no better off coming to this forum!

 

[littlespark]

3 replies, I counted. And the TT mention was just an example. There was no mention of it in OP.

Not really contradictory advice that I can see….
And if OP wants to save money, move out of London, because even changing a lightbulb down there costs an arm and a leg.

 

[nicebutdim]

2 replies and somewhat contradictory advice! the poor OP is no better off coming to this forum!

OP might do better to ask each electrician who quoted for reasoning behind their proposals.

Some proposals make sense, although not mandated by regulation, while others seem to be borne of myth. I'd be wary of any electrician who invents regulations, or who unquestioningly accepts information, as it would lead me to believe they know little of regulatatory requirements beyond what they've been told at one time or another.

As a caveat I would add that some regulations are open to differing interpretation, such as precisely what constitutes double pole isolation in specific circumstances, but plenty are very clear or even non-existent.

 

[DefyG]

Not really contradictory advice that I can see….

I did say somewhat! The OP came here for some clarity on the situation but hasn't got it.
But we all know its not 'black and white' I've always thought if you get 6 or 10 sparks quoting for same job you will end up with 6 or 10 different ideas and prices but all could be compliant!!

 

[mainline]

Re (2), for a TT installation (earth rod rather than supplier earth), using DP RCBOs is essential

Can you elaborate please as to why it would be absolutely necessary


edit: Just noticed @westward10 post

 

[pc1966]

Can you elaborate please as to why it would be absolutely necessary

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.

 

[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.