Spd & 18th..............,,,,,,

[bigspark17]

So am i correct than reg 443.4 means unless we provide a risk assesment that states why we are not using a spd in consumer unit changes then we must fit one??

 

[Nigel]

if only applies to commercial only .
wait until the Chinese get their act together the price will drop.

That is not correct. In single dwellings then if the value of equipment protected is less than the cost to install an SPD then no SPD required. However; if the dwelling had medical electrical equipment in then it would require SPD protection.

 

[Nigel]

So am i correct than reg 443.4 means unless we provide a risk assesment that states why we are not using a spd in consumer unit changes then we must fit one??

The reg does not say you need to provide one. Just that one needs to be carried out.

 

[Nigel]

That’s how I interpret it.

Not sure how you can carry out a risk assessment however because it states that you have to do a calculation with the different lengths of each element of the distributions various cable lengths.

Lpal, Lpcl, Lpah & Lpch

Other than asking the DNO not sure how these can be determined.

So I guess the only real way is to add type 2 devices to each CU adding £200+ to each job?

Table 443.1 tells you what to do when the distance of the network cable is unknown.

 

[Nigel]

An rcbo is not a spd! I dont see a way of ommiting it how the reg is worded

I agree. It is possible but very difficult to do.

 

[Nigel]

The Hager 18th seminar chap basically said when it comes to single dwellings then if it’s TT/overhead or has PV install a SPD.....If it doesn’t then you don’t really have to worry about it.

Sounds like they are talking crap. No mention whatsoever of supply arrangements in the regs.

 

[Nigel]

Has anyone actually carried out the calculation assuming a few figures that you aren’t going to know like the length the supply cable to the DNO TX? Unless your bang on top of the TX I can’t see it ever being above 1000.

CRL = Fenv /(Lp x Ng)


Fenv is an environmental factor selected according to Table 443.1
Lp is the risk assessment length in kilometres, and
Ng is the lightning ground flash density measured in flashes per square kilometre per year relevant to the location of the power line and connected structure.

Unless you can get all the above info then your going to fitting them on commercial jobs..

For domestic a get-out-clause is given for ‘single-dwelling units’ where the ‘total value of the installation and equipment therein does not justify such protection”.

For someone with just a sky box and tv, doesn’t really justify such protection. For someone that has multimedia setups, intelegent lighting controls, smart heating controls and so on it probably does justify having one fitted.

For the cost of them which aren’t massively expensive then it would be worth having a chat with the customer about having one fitted. Last house I done spent 7K on a HDMI matrix so I don’t think he would be bothered about an extra 60 quid for a SPD.

I think not to install them would be a non-conformance. Personally I won’t be giving an option. If they need them then my quote will have them in or I won’t be doing the works.

 

[Nigel]

From what I’ve read a type 2+1 SPD for TT overhead.

Type 2 if underground

type 1 or type 2+1 if lightning protection in place

https://www.hager.co.uk/files/download/0/4540_1/0/Surge_Protection_Guide.pdf

Page 17 quick selection guide of SPD’s

I would install a Type 1 if it was at the incomer.

Then Type 2 at other DBs down the line.

Type 3 if a vital bit of equipment was installed like a server or fire alarm panel.

 

[Midwest]

Someone's been busy posting this afternoon; I don't have a scooby, and too busy making fairy cakes.

 

[Ian1981]

all I know that is you have a LPZ then a type 1 is required at the origin to protect against lightning strikes.
As regulation 543.4.1.1 refers an spd installed at the origin shall be a type 1 or 2.
Regulation 534.4.1.4 says that where the structure is not equipped with an external lightning system or doesn’t require protection against lightning strikes,type 2 SPD’s shall be installed as close as possible to the origin.

So by that I conclude that SPD’s of a type 1 nature are not required if you have no LPZ

 

[Markyd]

SO........YES OR NO.....DOMESTIC

 

[Ian1981]

SO........YES OR NO.....DOMESTIC

Yes........... maybe.......

 

[Nigel]

It reads as a Type 1 will not comply at all for switching surges. Type 1 is only suitable for lightning protection.

However just because a property does not have LPZ protection does not mean it does not need protection against lightning strikes - hence the risk assessment calculation in 443.5.

So if the result of the risk assessment directs to install SPDs then a combined Type 1/2 would be what is required in small installations.

Larger installs I would install a Type 1 at the mains and then Type 2 at DBs.

 

[Nigel]

SO........YES OR NO.....DOMESTIC

In the vast majority of domestic it would be a yes.

 

[Ian1981]

The risk assessment according to 443.5 is required if protection against transient over voltage is even required for electrical installations except single dwelling units.
If not performed then the installation shall be provided with transient over voltage protection.
Regulation 443.1.1 states that this section does not specify requirements for protection against transient overvoltages due to direct lighting strokes on a structure.
Again I do not see where a type 1 is required if no LPZ is present as figure 534.1 indicates the LPZ concept

It’s definitely one for debate/guidance/clarity?
I’m sure I’ll get there in the end

 

[markc123]

What Edition of the Regs will we be on before there’s absolutley no difference in opinion & it’s completely black and white?

30th edition? In the year 2140 ?