Consumer Unit I would be interested in your sage comments

[sheppertonspark]

Hi, a quote I just sent out to a customer. Have I interpreted the regs correctly ? You're welcome to use it if you think it's ok. P.S.it's meant to get the point across in laymans terms.

 

[Lucien Nunes]

I don't have time to comment fully but beware of presenting your opinion as fact. E.g.
Para. 1: 'In practice it will...'
para. 2: 'Manufacturers are stuck...'
para. 3: '...the cost is prohibitive...'
para. 4: 'The best future-proof option is...'

Beware also of simplifying things to the point that they become incorrect.
E.g. a risk assessment or cost/benefit decision on the advantage of fitting SPDs is rather more than noting whether the cost of the connected equipment exceeds that of the SPD. For that to be a valid criterion, one would have to assume that all vulnerable equipment in an installation would certainly be damaged within the expected service life of an SPD, if the SPD were not fitted.

Likewise, I am not sure your explanation of the change in RCD preferences is valid. Type A devices have been around for a long time and the limitations of type AC have always been known. Type A is recommended due to the increasing usage of loads that can produce a pulsating DC residual current. It is not true to say that type A is sensitive to both AC and DC without further qualification; only a type B fulfils that description.

I've ignored spelling and grammar as I'm sure you'll be proof-reading it again.

 

[pc1966]

As already mentioned by Lucien Nunes you need to make sure you clearly separate statements about the wiring regs from your opinion. There is nothing wrong with giving your opinion, but it must be clear what is needed and what you recommended. Also you have to remember that most customers, even those with a little knowledge from school physics, etc, will need a clear "plain English" explanation of things so your argument makes sense.

For example, on the SPD aspect you might want to phrase it something like:

The current standard introduced a requirement to always fit Surge Protection Devices (SPD) in situations where there are significant consequences arising from lightning-induced or other surges (e.g. loss of life, risk to business operations, etc), and for all other cases a risk assessment shall be performed to decide if the financial risk of damage to equipment (e.g. to televisions, computers, etc) is greater than the cost to fit the SPD. My recommendation is to always fit one as the additional cost is small (around £100) when considered over the lifetime of the unit, and value at risk from not fitting one may be higher than the price of the equipment (e.g. lost data on damage PCs or laptops, inconvenience from having to wait for repairs or replacements).

Similarly the advice on RCDs, while valid, does not read very well. Also you are proposing RCBOs but not explaining the significant advantages of them. Maybe you could phrase it something like this:

The current standard require almost all circuits in a Domestic Dwelling to be protected by an Residual Current Device (RCD) for protection against electric shock, and to reduce the risk of fire. These devices continually monitor the power used and if any is detected going astray (for example, someone touching a cut cable in the garden after a lawnmower accident) they rapidly switch of the circuit(s) connected to them for safety. Previously it was common to have only one or two RCD for the whole house for these sort of shock risks, and then to use separate Miniature Circuit Breakers (MCB) to protect individual circuits from overload (e.g. light, 13A sockets, cooker, etc). This arrangement has a number of limitations, for example, the original RCD type (known as "type AC") may not reliably trip if a fault involves electronic systems, and a fault that trips the RCD typically takes out several circuits causing additional inconvenience and making fault finding harder. My recommendation is to fit RCBO that combine both the RCD and MCB protection in a singe device that is used for each circuit, and to specify "type A" that are better with electronic faults. They provide greater overall reliability, less likelihood of spurious trips on healthy circuits, and allow rapid identification of faults should they occur.

I think most folk on this forum also share your view on AFDD, they are expensive so far and only provide a small increase in protection. I don't think they are actually required in any case, rather are recommended in some cases where a high risk from fire is identified (either it starting, or the consequences).

My 2p worth!

 

[sheppertonspark]

Thank you Lucien and P for your comments. Taken on on board !

 

[Midwest]

recommendation is to always fit one as the additional cost is small (around £100) when considered over the lifetime of the unit,

I thought surge protectors had a limited life span, i.e. shorter than a typical CU and associated devices?

 

[Mike Johnson]

Only comment is that insurance companies can not void a claim, you have a contract with the insurance company and they must honour that contract, the only time they can void a claim is if on the insurance application the details where deliberately made out to deceive/fraud the company. What they can do, if in the opinion of the company contributory negligence was a deciding factor of the damage being claimed for then they can reduce the amount of the claim, but I can not emphasise this strongly enough, an insurance company can not void your claim.

The SPD we use in France are to the most point one hit wonders, can go on one lightning strike (common) or last a few strikes, but nevertheless they need replacing about every two years as indicated by the flag on the unit.

 

[pc1966]

I thought surge protectors had a limited life span, i.e. shorter than a typical CU and associated devices?

The life limit of these depends on how much lightning you are getting. The "end of life" flag seems to be the point when they have heated so much that the solder-fuse melts and disconnects them. Most of the ones I see offered have plug-in replaceable units so can be changed fairly easily, even by a competent home owner.

If you are seeing a life of only a couple of years then I expect that without one you would be seeing a lot of damaged electronics instead!

Also you can get beefier ones, the "type 1" that can handle quite a lot for input board protection, etc, but they cost a lot more (from memory £300-ish for single phase, £800-ish for three-phase)

I think the bigger problem with this, and it is the same for RCD, is practically none of the general population will know to check them, and even if they are told when new, they won't get round to doing it. The argument for 6 monthly RCD testing was it could be done when the clocks change, but that never happens.

I'm not a professional electrician, but if I were in that business it would be tempting to give each owner a laminated cheat-sheet on checking the SPD and RCD each time the clocks change and how to do it safely (along with company logo and contact details). More importantly, I would try and get thier permission for a 6-month text reminder and offer to do the checks for them for a small fee!
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Going back to the AFDD issue, considering they add around £1-2k to the cost of a new consumer unit, I personally would suggest that if it were affordable then spending that amount on something like a proper wired-in / coupled smoke & fire alarm, and maybe a couple of extinguishers for kitchen / garage, as better protection for the money.

 

[Midwest]

The life limit of these depends on how much lightning you are getting. The "end of life" flag seems to be the point when they have heated so much that the solder-fuse melts and disconnects them. Most of the ones I see offered have plug-in replaceable units so can be changed fairly easily, even by a competent home owner.

If you are seeing a life of only a couple of years then I expect that without one you would be seeing a lot of damaged electronics instead!

Also you can get beefier ones, the "type 1" that can handle quite a lot for input board protection, etc, but they cost a lot more (from memory £300-ish for single phase, £800-ish for three-phase)

I think the bigger problem with this, and it is the same for RCD, is practically none of the general population will know to check them, and even if they are told when new, they won't get round to doing it. The argument for 6 monthly RCD testing was it could be done when the clocks change, but that never happens.

I'm not a professional electrician, but if I were in that business it would be tempting to give each owner a laminated cheat-sheet on checking the SPD and RCD each time the clocks change and how to do it safely (along with company logo and contact details). More importantly, I would try and get thier permission for a 6-month text reminder and offer to do the checks for them for a small fee!
[automerge]1583916116[/automerge]
Going back to the AFDD issue, considering they add around £1-2k to the cost of a new consumer unit, I personally would suggest that if it were affordable then spending that amount on something like a proper wired-in / coupled smoke & fire alarm, and maybe a couple of extinguishers for kitchen / garage, as better protection for the money.

I was just being pedantic, as you were offering the OP advice on what to state. So they have a limited life span, lesser than the CU. Have to get these things right.

 

[pc1966]

I was just being pedantic, as you were offering the OP advice on what to state. So they have a limited life span, lesser than the CU. Have to get these things right.

That is a fair point!

 

[Mike Johnson]

My French residence is in the Thunderstorm capitol of France dept24, we unplug our telephone and computers whenever a storm is brewing and when we leave at the end of the season, I have stood in the Dining room and watched a ball of blue fire cross the room, my car outside lit up like a Christmas tree, everything went on, that was the first time our Router was burnt out, happened again whilst out shopping and unable to unplug it, so these concerns are real in certain areas, the cost of a three phase SPD is not to be sniffed at.

 

[pc1966]

My French residence is in the Thunderstorm capitol of France dept24, we unplug our telephone and computers whenever a storm is brewing and when we leave at the end of the season, I have stood in the Dining room and watched a ball of blue fire cross the room, my car outside lit up like a Christmas tree, everything went on, that was the first time our Router was burnt out, happened again whilst out shopping and unable to unplug it, so these concerns are real in certain areas, the cost of a three phase SPD is not to be sniffed at.

Out of curiosity, what sort of supply do you have there in you French site? (farm style building from overhead wires, or a typical urban area with underground SWA cable, etc.)

It would be interesting to see the stats on SPD life expectancy. Up here is dull Scotland I have not seen and surge protection blown by induced effects, but a fair few things without protection gone over the years.

Mind you, I probably have more cause to fear divine retribution than most!

 

[Mike Johnson]

Underground SWA three phase.

 

[sheppertonspark]

The life limit of these depends on how much lightning you are getting. The "end of life" flag seems to be the point when they have heated so much that the solder-fuse melts and disconnects them. Most of the ones I see offered have plug-in replaceable units so can be changed fairly easily, even by a competent home owner.

If you are seeing a life of only a couple of years then I expect that without one you would be seeing a lot of damaged electronics instead!

Also you can get beefier ones, the "type 1" that can handle quite a lot for input board protection, etc, but they cost a lot more (from memory £300-ish for single phase, £800-ish for three-phase)

I think the bigger problem with this, and it is the same for RCD, is practically none of the general population will know to check them, and even if they are told when new, they won't get round to doing it. The argument for 6 monthly RCD testing was it could be done when the clocks change, but that never happens.

I'm not a professional electrician, but if I were in that business it would be tempting to give each owner a laminated cheat-sheet on checking the SPD and RCD each time the clocks change and how to do it safely (along with company logo and contact details). More importantly, I would try and get thier permission for a 6-month text reminder and offer to do the checks for them for a small fee!
[automerge]1583916116[/automerge]
Going back to the AFDD issue, considering they add around £1-2k to the cost of a new consumer unit, I personally would suggest that if it were affordable then spending that amount on something like a proper wired-in / coupled smoke & fire alarm, and maybe a couple of extinguishers for kitchen / garage, as better protection for the money.

Good point but the fire alarm etc. not a lot of use if you are out at the time !!
[automerge]1583962281[/automerge]

Only comment is that insurance companies can not void a claim, you have a contract with the insurance company and they must honour that contract, the only time they can void a claim is if on the insurance application the details where deliberately made out to deceive/fraud the company. What they can do, if in the opinion of the company contributory negligence was a deciding factor of the damage being claimed for then they can reduce the amount of the claim, but I can not emphasise this strongly enough, an insurance company can not void your claim.

The SPD we use in France are to the most point one hit wonders, can go on one lightning strike (common) or last a few strikes, but nevertheless they need replacing about every two years as indicated by the flag on the unit.

Hi Mike, I was thinking that in the future insurance cover for electronic equipment may be dependent on having SPD.

 

[Mike Johnson]

It may well be, but what if you have three or four hits in one storm and the whole thing is compromised and the CU blows up and burns down, how will they know what happened first or even if you had an SPD if the whole building is destroyed?

 

[davesparks]

Hi Mike, I was thinking that in the future insurance cover for electronic equipment may be dependent on having SPD.

You can't use your predictions of what might happen in the future as a means of pressure selling SPDs.

 

[Mike Johnson]

Not trying to pressure sell SPD's, it's the insurance aspect I am eluding too, but it's a good idea to either have them or unplug your sensitive equipment when the property is unattended.

 

[pc1966]

Good point but the fire alarm etc. not a lot of use if you are out at the time !!

Thing is I suspect the majority of fires are not from wiring faults, more likely leaving stuff on in the kitchen or elderly smokers dropping cigarettes in to their chair. So an alarm helps there, and personally it is more a fire while I am sleeping that worries me than when I'm out!
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Underground SWA three phase.

That is a surprise!

Worst lightning related stuff I saw was in Indonesia where the guy showed me the main busbar chamber for the institute and the evidence of it flashing over.

Out of curiosity, what sort of SPD are you using?

For our new project we need to use a type 1+2 SPD for 3-phase (as structure has lightning protection) though we don't expect much risk. Were looking at the Wylex NHSPD4441T12 or Proteus SPD/T12/100KA/4P as our options just now so it would be useful to get feedback on real-world experience of SPD in an area that is going to test things harder than up here.

 

[Mike Johnson]

So far I have replaced two of these: 15kA 4 Module 3 Pole and Neutral Type 2 Surge Protector - https://www.cef.co.uk/catalogue/products/1047310-four-pole-surge-protection-device?&utm_source=google&utm_medium=cpc&utm_adgroup=&utm_campaign=&ppc_keyword=&gclid=Cj0KCQjwu6fzBRC6ARIsAJUwa2Sfw6cnA4oqUMRO8Lt3lxz1F7SuDHIg7HkCqa2w6A7cB6TWcUzkprAaAk1YEALw_wcB&gclsrc=aw.ds expensive, I now have a very cheap oriental version that I am trying out in parallel.

I just found this on e-bay, makes my very cheap oriental version seem positively expensive: 4-Poles Lightning Arrester Din Rail Over Voltage Surge Protector Device UK | eBay - https://www.ebay.co.uk/itm/4-Poles-Lightning-Arrester-Din-Rail-Over-Voltage-Surge-Protector-Device-UK/173965195762?_trkparms=aid%3D1110004%26algo%3DSPLICE.COMP%26ao%3D1%26asc%3D225075%26meid%3D9688108c5744450d828dd36a70bd28f8%26pid%3D100008%26rk%3D6%26rkt%3D10%26sd%3D292881829230%26itm%3D173965195762%26pmt%3D1%26noa%3D0%26pg%3D2047675%26algv%3Ddefault%26brand%3DUnbranded&_trksid=p2047675.c100008.m2219

 

[pc1966]

So far I have replaced two of these: 15kA 4 Module 3 Pole and Neutral Type 2 Surge Protector expensive, I now have a very cheap oriental version that I am trying out in parallel.

They are type 2, but in your location is sounds like you really need a type 1 as they can cope with much higher energy (direct effect, 10/350us, not induced with the 8/20us time scale).

I'm not sure parallel operation works well - whichever device conducts first will get most of the current and eventually blow, so you just delay the replacement. If you can afford to get a type 1+2, or to save a bit of money if you have working type 2 just now then put a type 1 fist and then some inductance before your type 2.

Usually they say 10m of cable is enough for surge protection discrimination, but if that is too long, as it almost certainly is, then a few turns of 25mm cable suitably cable-tied (one for each phase) can be used to get the impedance needed. Somewhere I remember seeing specs for creating the inductance with coil wire, was something like 2-4 turns on 10cm or so diameter, and a note about not pushing the full cable rating as heat won't escape so easily from the turns. Found it here:

https://www.eltek.com/globalassets/media/downloads/requirements/b-2024623-1-5-1.pdf

Has 2 turns on 110mm diameter to give 2uH series inductance as one example on page 8.

Erico has a really useful catalogue that covers some of this, search for E907W-WWEN.pdf also if you search for "BEAMA Guide to Surge Protection Devices" it is another useful guide on SPD, more than most will care to read!

 

[DPG]

So far I have replaced two of these: 15kA 4 Module 3 Pole and Neutral Type 2 Surge Protector - https://www.cef.co.uk/catalogue/products/1047310-four-pole-surge-protection-device?&utm_source=google&utm_medium=cpc&utm_adgroup=&utm_campaign=&ppc_keyword=&gclid=Cj0KCQjwu6fzBRC6ARIsAJUwa2Sfw6cnA4oqUMRO8Lt3lxz1F7SuDHIg7HkCqa2w6A7cB6TWcUzkprAaAk1YEALw_wcB&gclsrc=aw.ds expensive, I now have a very cheap oriental version that I am trying out in parallel.

I just found this on e-bay, makes my very cheap oriental version seem positively expensive: 4-Poles Lightning Arrester Din Rail Over Voltage Surge Protector Device UK | eBay - https://www.ebay.co.uk/itm/4-Poles-Lightning-Arrester-Din-Rail-Over-Voltage-Surge-Protector-Device-UK/173965195762?_trkparms=aid%3D1110004%26algo%3DSPLICE.COMP%26ao%3D1%26asc%3D225075%26meid%3D9688108c5744450d828dd36a70bd28f8%26pid%3D100008%26rk%3D6%26rkt%3D10%26sd%3D292881829230%26itm%3D173965195762%26pmt%3D1%26noa%3D0%26pg%3D2047675%26algv%3Ddefault%26brand%3DUnbranded&_trksid=p2047675.c100008.m2219

Looks like a quality Ebay seller
From the Leicestershire in Hong Kong and less than 97% feedback!