China has been making e.g. iPhones for well over a decade, so as you point out, they can do high-end technology. I am not quite sure why a domestic install would need a Type 1 SPD.

I was surprised myself, but reading the pdf from surgedevices and conversation thereafter with them, the advice is that if the supply cable is from overhead cables and not underground cable than to install a type 1 +2 device. A property which may need a cu relocation due to an building extension has DNO cable attached to the external wall..a overhead supply....

In such a case does a type 1+2 become necessary / appropriate?

I believe that Chint which has a presence in the UK market is Chinese.

I have also sent an email to Geya Electricals asking whether they have a European UK presence and if they OEM for any UK brands. See what they come back with???

Adam Kuzack said:

A property which may need a cu relocation due to an building extension has DNO cable attached to the external wall..a overhead supply....

What sort of cable please? Bare wires on insulators, or ABC?

I am not sure...it's a black cable that is attached to the wall and supplies a row of properties...I guess abc cable...

Would it affect the spd requirements?

To help you identify

Aerial bundled Cable (ABC)actually looks like a bundle and is easily identified, because the twists and ties make it look bumpy - this is 3 phases and Neutral but single phase ABC would be just 2 individually insulated wires twisted.

plain round is usually Concentric  which may be earthed concentric - for TNC-s

or Split con allows N-E separation, and looks the same-ish from the outside but half the strands of the outer are insulated - Not always as clearly as this example,

Split concnetric is ised on TNS or TNC-s on the load side of the NE split

Mike

This is the photograph taken of the incoming cable attached to the external wall. As it is apparently not an underground supply cable, I assume it's an overhead supply cable. Therefore, a greater risk of lightning strike and type 1 +2 spd. 

I do not have vast experience in this and would be happily guided by the forum  

Looks to me like it might be an "under eaves" supply - not commonly done these days, but lots about on older terraced properties. At some point the whole terrace will receive a supply - which can either be from overhead (i.e. cables hung from poles) or from underground with a "cut out" box on the outside of one of the properties - you might have to wander around to find it. Personally I'd consider how it arrives at the terrace to be the determining factor rather than how it enters your particular house (compare with a supply to a block of flats, with "sub main" cables to individual flats).

That said, concentric cables run overhead are often considered to be equivalent to underground as the cable is self screening to some extent. ABCs are probably less vulnerable to having surges induced on then open wire (at least between conductors - which is probably what you're interested in if your have a TN system).

   - Andy.

Looks like a number (4) of concentric cables - presumably the fat one coming in on the left and the others, including the thin one bent round going out to the right to three consumers meters for different users. But that is a guess - we cannot really see.

I think that is just junctions, and DNO the death or glory  fuses will be nearer the transformer, where ever that  is.

Its also seems to be upside  down and at risk of getting water ingress via the cable entries. But that is an ecumenical   DNO matter.

Mike.

the thing that makes it overhead, is where the incoming supply comes from

Is it something like this ?
This image is 3 phase ABC pole to pole on top, and under that single phase ABCs to houses left and concetric to the right, and box of fuses or removable links pole-top. Oh and a bare stay wire (guy-line if you like)

AJJewsbury said:

That said, concentric cables run overhead are often considered to be equivalent to underground as the cable is self screening to some extent.

In the surge protection world, we are also concerned about L-Earth and N-Earth.

The Type 1 need, though, is about direct strike to overhead cable or pole-mounted transformer - more common with bare overhead, but can happen with insulated overheads especially pole-mounted transformer supply. By overheads to be clear I mean where there is a span (or catenary) between poles in the LV supply network to the property (or if looped as stated by Andy, nearby property).

People will be quick to point out that 443 does not address direct strokes (and is not intended to). This is perfectly correct, but I would draw attention to 543.1 which does introduce direct strokes, and the first para says the section focuses "mainly on 443, but also can eb used in conjunction with BS EN 62305 or otherwise stated."

In particular, though, with this issue, see NOTE to 534.4.1.1.

Thank you for the comments on the type of cable that may be supplying the property. I will investigate further. What seems to be the  / opinion with regards to whether a type 1 spd will be required? What are the guiding factors that will determine whether it will be Type 2 or a Type 1+2 device - could do with some guidance on this question. 

Thanks 

Adam Kuzack said:

What are the guiding factors that will determine whether it will be Type 2 or a Type 1+2 device - could do with some guidance on this question. 

See NOTE to 534.4.1.1, and on top of that, "where required by BS EN 62305" for buildings with LPS (and therefore Section 443 of BS 7671 does not apply).

Adam Kuzack said:

What are the guiding factors that will determine whether it will be Type 2 or a Type 1+2 device - could do with some guidance on this question. 

See NOTE to 534.4.1.1, and on top of that, "where required by BS EN 62305" for buildings with LPS (and therefore Section 443 of BS 7671 does not apply).

Graham, can we keep it simple please? :-)

Correct me if I am wrong, but a LPS would be fitted to e.g. a steel-framed factory and requires Type 1. In the absence of an LPS (and the risks which required it in the first place), Type 2 will do.

What I am unclear on is a lightning conductor which protects e.g. a church spire. If I remember my physics lessons correctly, the idea is to conduct the electricity in the sky to ground in order to prevent it building up and making lightning. Would such a lightning conductor amount to an LPS?

Chris Pearson said:

Would such a lightning conductor amount to an LPS?

Yes, although there are LPS to BS 6651 and LPS to BS EN 62305. BS 7671 no longer recognizes BS 6651 (because it's been withdrawn) ...

More to the point, is the question of whether the LPS is bonded to MET. This was not always done, but is usually now where BS EN 62305 applies - if it's done, then you probably need Type 1 - but that would be indicated by BS 62305 anyway (which you'd have to apply according to BS 7671).

Omitting Type 1 where BS EN 62305 says it should be provided can cause injury, fire, or extensive damage.

Overhead supplies are also subject to damage from direct strikes, and omitting Type 1 here can also cause extensive damage or injury.

Chris Pearson said:

Correct me if I am wrong, but a LPS would be fitted to e.g. a steel-framed factory and requires Type 1.

What are the driver here? There are small factories and large ones?  What's the nature of the supply, and what's the direct lightning stroke risk? (agree, increased if steel-framed large structure and not a lot else in the vicinity ... but again 443 leaves the decision to BS EN 62305).

So, the typical case where BS EN 62305 isn't directly involved, but Type 1 may be needed, is the domestic property, village shop, etc., where there's an overhead supply ... and the risk remains. I think everything else you're getting BS EN 62305 out for (and would you insurance cover you for making the decision on issues covered by that standard)?