Surge protection devices (SPD)

[mattg4321]

Hi guys, hopefully someones going to be able to point me in the right direction here.

We do a lot of work for a small retirement home locally that has recently decided to fit lightning protection. We've pretty much been strong armed into fitting SPD's on behalf of the lightning firm (LF). Being honest I don't have a great deal of experience with them and tried to sidestep the job. No such luck!

The lightning firm(LF) are supplying SPD's, but have supplied little further information. What they have provided seems inconsistent and vague. IMO they don't really seem to 100% know what they are talking about.

1.We have a 3 phase SPD to be fitted at the main intake position. There is a 3 phase DB here, but it has no spare ways. LF have said we need to split the tails and fit a 3 phase switchfuse isolator before connecting to SPD in adjacent enclosure.

2.We have 2x SWA cables running external around the building which we are told need SPD's at the load end. These supply a 3 phase washing machine and a 3 phase cooker (20A each). LF have been pretty vague here and sometimes use the word 'isolator' and sometimes 'switchfuse' and don't appear to know the difference. They want us to cut into the SWA before the existing appliance isolator and fit a 63A switchfuse (or isolator - who knows). This would isolate the SPD.

I'm not sure why 63A has been specified?

I'm not sure if I need to fit a switchfuse or an isolator? I'm not even sure what would stop someone turning it off by accident?

If I cut into the SWA at the load end I'm going to need to double up the cables in the supply side of the isolator - doesn't seem like the greatest design?

Can anybody offer some help/point me in the right direction here. I don't like just blindly following instructions that don't make sense to me.

Cheers

 

[mattg4321]

This is the product to be supplied

https://library.e.abb.com/public/d3e03f037f6b49558c66c5ba81181465/ESP 415 --- Series.pdf

 

[Pete999]

Hi guys, hopefully someones going to be able to point me in the right direction here.

We do a lot of work for a small retirement home locally that has recently decided to fit lightning protection. We've pretty much been strong armed into fitting SPD's on behalf of the lightning firm (LF). Being honest I don't have a great deal of experience with them and tried to sidestep the job. No such luck!

The lightning firm(LF) are supplying SPD's, but have supplied little further information. What they have provided seems inconsistent and vague. IMO they don't really seem to 100% know what they are talking about.

1.We have a 3 phase SPD to be fitted at the main intake position. There is a 3 phase DB here, but it has no spare ways. LF have said we need to split the tails and fit a 3 phase switchfuse isolator before connecting to SPD in adjacent enclosure.

2.We have 2x SWA cables running external around the building which we are told need SPD's at the load end. These supply a 3 phase washing machine and a 3 phase cooker (20A each). LF have been pretty vague here and sometimes use the word 'isolator' and sometimes 'switchfuse' and don't appear to know the difference. They want us to cut into the SWA before the existing appliance isolator and fit a 63A switchfuse (or isolator - who knows). This would isolate the SPD.

I'm not sure why 63A has been specified?

I'm not sure if I need to fit a switchfuse or an isolator? I'm not even sure what would stop someone turning it off by accident?

If I cut into the SWA at the load end I'm going to need to double up the cables in the supply side of the isolator - doesn't seem like the greatest design?

Can anybody offer some help/point me in the right direction here. I don't like just blindly following instructions that don't make sense to me.

Cheers

Install an SPD at the intake position would be my guess, you're after chopping the supply during a lightening strike the intake seems to be the logical point to do this, I'll bow to expert explanation.

 

[Toneyz]

Only fitted them off Eaton MCCB pane3l boards off spare way close to the main switch.

 

[Pete999]

When I fitted SPDs it was a requirement to fit them prior to any loads to prevent damage

 

[mattg4321]

I need to fit one at main intake, but also at load end of externally run cables - incase of a lightning strike affecting these.

 

[westward10]

Is there a main protective bond to the lightning protection, this is essential to lessen the chances of a strike jumping through the wall to the electrical system cpcs.

 

[Strima]

Why have they suddenly decided to fit LP? The likelihood of a building strike in the UK is pretty slim, there is a greater risk of induced current travelling down the supply from other locations.

By adding LP to the building they could be increasing the risk of a strike as it gives a good path to earth. Are they also informing home and business owners in the local area of this installation as this also increases their risk of damage through an indirect strike.

 

[westward10]

Adding lightning protection to a structure has absolutely no effect on increasing the probability of a strike.

 

[mattg4321]

Is there a main protective bond to the lightning protection, this is essential to lessen the chances of a strike jumping through the wall to the electrical system cpcs.

I don't know the answer to this. I have just been asked to carry out the works I detailed above. To be honest I'd rather sidestep it, but that's not really an option. I could just fit what they've told me to fit but I'd like to know I'm doing the right thing.

Any ideas on the above WW10?

 

[westward10]

If you are going to do these works a main protective bond will be required.

 

[westward10]

You normally fit a type 1 or 2 LPD at the source of supply however these are not guaranteed to protect individual items of sensitive equipment. It sounds like they have decided that certain appliances may require further localised protection with maybe a type 3 device but personally I would not have thought a cooker and washing machine would justify this.

 

[mattg4321]

Any thoughts on switchless/isolators anyone? Also why 63A?

 

[westward10]

Just reread your opening post and this could have something to do with the cables being external to the building fabric. Have you spoken to the people who have recommended this.

 

[mattg4321]

I have, they keep dodging the questions! I get the impression they don't really know why they are speccing what they are

 

[PEG]

Adding lightning protection to a structure has absolutely no effect on increasing the probability of a strike.

But it does,because of the very fact you are generating a deliberate and attractive point,for that ionisation to occur.

Two identical structures,close together,with one having LP,which one has the increased chance of being the target?

It is surely the reason why the lone golfer is the thunderstorms first victim

 

[westward10]

It makes no difference.

 

[Wilko]

Just for fun - I've seen this effect several times - lightning appears to have bypassed the tower top protection and smacked at some other place. My take is we can try to control Nature, but sometimes she just lets us know who's in charge .

 

[westward10]

Lightning strikes are not governed by the height of things or what they are constructed of. Lightning protection is not there to attract it but to divert it from the structure if it does strike. Why would you want to attract it!!

 

[DPG]

Lightning strikes are not governed by the height of things or what they are constructed of. Lightning protection is not there to attract it but to divert it from the structure if it does strike. Why would you want to attract it!!

Really?

 

[Pete999]

Really?

Why do tall buildings have lightning conductors? - https://www.reference.com/science/tall-buildings-lightning-conductors-c3e8420c85c479a6

 

[DPG]

Why do tall buildings have lightning conductors? - https://www.reference.com/science/tall-buildings-lightning-conductors-c3e8420c85c479a6

Not sure if you intended to reply to me Pete, but my point was replying to the comment earlier about height not affecting risk of lightning strike. Which it does.

 

[westward10]

Really?

You can have two structures side by side with one taller than the other but there is no guarantee it will not strike the shorter over the taller one.

 

[Pete999]

Not sure if you intended to reply to me Pete, but my point was replying to the comment earlier about height not affecting risk of lightning strike. Which it does.

No Mate it was just that your's was the last post, so I added my answer to it, wasn't questioning your post in any way, sorry if it caused any misunderstanding, if it did it was unintentional.

 

[DPG]

You can have two structures side by side with one taller than the other but there is no guarantee it will not strike the shorter over the taller one.

No, there's no guarantee as such, but the odds are higher for the taller building. To take it to the extreme, it's very unlikely a bungalow would get struck next to the Eiffel Tower. And don't say yes, that's because there isn't a bungalow there

 

[DPG]

No Mate it was just that your's was the last post, so I added my answer to it, wasn't questioning your post in any way, sorry if it caused any misunderstanding, if it did it was unintentional.

No worries at all mate.

 

[Pete999]

No worries at all mate.

Thank's mate, last thing on my mind was trying to upset people.

 

[DPG]

Thank's mate, last thing on my mind was trying to upset people.

We'll leave that to Burnsy eh!
No offence Burnsy me old mucker

 

[westward10]

Thank's mate, last thing on my mind was trying to upset people.

It's the first thing on my mind

 

[Pete999]

It's the first thing on my mind

We know

 

[mattg4321]

No one on this forum is experienced with fitting SPD's and can answer any of my questions?

Do I need switchfuses or isolators? Why fused at 63a on a 20a circuit?

Please!

 

[Pete999]

No one on this forum is experienced with fitting SPD's and can answer any of my questions?

Do I need switchfuses or isolators? Why fused at 63a on a 20a circuit?

Please!

http://www.purgethesurge.com/pdf/Presentation/TPS3_Consultant_Presentation_CE_2013.pdf

 

[marconi]

Hi guys, hopefully someones going to be able to point me in the right direction here.

We do a lot of work for a small retirement home locally that has recently decided to fit lightning protection. We've pretty much been strong armed into fitting SPD's on behalf of the lightning firm (LF). Being honest I don't have a great deal of experience with them and tried to sidestep the job. No such luck!

The lightning firm(LF) are supplying SPD's, but have supplied little further information. What they have provided seems inconsistent and vague. IMO they don't really seem to 100% know what they are talking about.

1.We have a 3 phase SPD to be fitted at the main intake position. There is a 3 phase DB here, but it has no spare ways. LF have said we need to split the tails and fit a 3 phase switchfuse isolator before connecting to SPD in adjacent enclosure.

2.We have 2x SWA cables running external around the building which we are told need SPD's at the load end. These supply a 3 phase washing machine and a 3 phase cooker (20A each). LF have been pretty vague here and sometimes use the word 'isolator' and sometimes 'switchfuse' and don't appear to know the difference. They want us to cut into the SWA before the existing appliance isolator and fit a 63A switchfuse (or isolator - who knows). This would isolate the SPD.

I'm not sure why 63A has been specified?

I'm not sure if I need to fit a switchfuse or an isolator? I'm not even sure what would stop someone turning it off by accident?

If I cut into the SWA at the load end I'm going to need to double up the cables in the supply side of the isolator - doesn't seem like the greatest design?

Can anybody offer some help/point me in the right direction here. I don't like just blindly following instructions that don't make sense to me.

Cheers

I did some research on domestic SPDs on behalf of my mother-in-law after the overhead 4 wire supply in her street was struck by lightning which damaged her skybox, TV and washing machine.

MK do some sockets but they mainly deal with voltage spikes and noise and when they are called into action the internal varisters or neons lose some or all of their 'life'. The socket for example has a cartridge which has to be replaced - I cannot remember if their is any indication that it needs to be swapped for a new cartridge. There are Consumer Unit modules too but these I seem to remember do have a flag to indicate they need replacing. I consulted MK Technical and they said the devices are not promoted to protect against lightning.

Anyway, this preamble is to say whatever SPD is fitted one needs to think about a regular inspection routine for some kind of flag that the device is still functional or not. Or, whether as a matter of course they must be replaced periodically.

My M-I-L thought the cost/benefit of SPDs in her home did not stack up.

 

[marconi]

No one on this forum is experienced with fitting SPD's and can answer any of my questions?

Do I need switchfuses or isolators? Why fused at 63a on a 20a circuit?

Please!

For your question in bold - I will deal with the second question shortly.

Please see the installation instructions for the PSD device you mentioned earlier:

https://library.e.abb.com/public/ba7860c5a8624189a51df9d903c2460a/ESP 415XXX Series ii 12.11.12.pdf

where at paras 4.6 and 4.7 it says:

4.6 Isolation It is good practice to be able to isolate or disconnect the ESP Protector from the supply. The means of isolation should therefore be installed in the connection to the ESP ProtectorThe supply to the entire distribution board should not be switched off on many computer power supplies and other critical loads. (see 4.7 - Fuse connecting leads).

4.7 Fuse connecting leads The connecting leads to the phase/live terminals of the ESP Protector should be fused. This is to protect the connecting leads in the event of a short circuit. The fuse to the ESP Protector (FSPD) should be lower than the upstream supply fuse FS by a sufficient enough factor to ensure fuse discrimination. As a general guide a factor of at least 2 could be used (FSPD ≤ 0.5 FS), where the maximum fuse to the ESP Protector required is 250 Amps (if the supply fuse is 500 Amps or greater). Refer to the fuse manufacturer’s operating characteristics to ensure discrimination, particularly where an installation includes a mixture of types of fuse, or of fuses and circuit breakers.

There are also important instructions on keeping short the cable lengths to the SPD via the isolator and fuse. So switch uses are ideal to provide isolation and over current protection in one and thereby keep cable runs as short as practical.

 

[marconi]

'Why fused at 63A on a 20A circuit'. You are referring to SPD protection for the 2 SWA supplues. You mntion the load they supply but not the size of their OCPDs. The guidance is provided in para 4.7 above viz (FSPD ≤ 0.5 FS) - so knowing the OCPD for each SWA supply you can calculate the fuse size to protect the wiring to the SPD.

That's how I read it - but I think having done the calculations and decided on cable sizes I would contact Furse technical department to confirm. Contact details are at the bottom right of the installtion instructions.

 

[marconi]

I forgot to mention, use cabling;

a. of csa equal to at least the 2 SWA's csas;

and

b. the largest you can fit into the terminals for the intake SPD.

You want to reduce skin effect and resistance/impedance of the branch off to the SPDs.

 

[marconi]

Further to my #36 - the guidance para 4.8 actually says a minimum of 16mm2 multistranded. Note well 4.9 and 4.10 about binding the cables together as well as keeping them short.

 

[mattg4321]

Thanks marconi. Reading through those instructions actually gives slightly more detail than the hardcopy ones I received from the firm doing the lightning conductors.

The SWA supplies are both 6mm 4core SWA with 20A OCPD. Why would they then specify 63A switchfuse or isolator?!

Ive also been wondering if I need to fit a switchfuse, or if I could fit an MCB in the same enclosure as the DIN rail mounted SPD. This would keep the tails to the SPD shorter and obviously keep the costs down to my customer.

 

[marconi]

Thanks marconi. Reading through those instructions actually gives slightly more detail than the hardcopy ones I received from the firm doing the lightning conductors.

The SWA supplies are both 6mm 4core SWA with 20A OCPD. Why would they then specify 63A switchfuse or isolator?!

If the upstream OCPD is 20A then the SPD can have a lower OCPD as stated in the installation instructions. Some form of isolation of the SPD is required if one wants to avoid turning off all power while servicing the SPD. If this is not an issue then the SPD can share the isolation provided for the cables and loads.

Ive also been wondering if I need to fit a switchfuse, or if I could fit an MCB in the same enclosure as the DIN rail mounted SPD. This would keep the tails to the SPD shorter and obviously keep the costs down to my customer.

OCPD for SPD must satisfy Fspd less than or equal to (0.5 x Fs), where Fs is upstream fuse or MCB, to provide discrimination. Fspd is providing short circuit protection for cabling to SPD.

The guidance allows you to do what you suggest; see paras 4.1 and 4.2. An advantage of installing it external but close is you do not have to turn off all power to maintain the SPD. The advantage of including it within DB is cables are shorter and SPD connected closer to intake.

Better informed now, you can have a discussion with the client on what he wants and why and how you propose to install the SPDs and why. Time for me to handover to electricians to resolve the niceties of installation.

 

[PEG]

It makes no difference.

You may need to read up on step leaders and streamers

Just a bit of banter...and it is accepted that lightning can hit a person,stood next to a high building,so,random is nature...

The fitting of a conductor,increases the probability of creating a streamer,which increases the odds,that it will make contact with the last step leader...don't shout at me,blame the scientists