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Topic Title: Changing distribution boards
Topic Summary: Surge protection
Created On: 15 January 2019 08:35 PM
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 15 January 2019 08:35 PM
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tillie

Posts: 937
Joined: 03 May 2006

Hi ,last summer I was asked to price up the changing of 4x 36 way distribution boards and 3x 12 way distribution boards in the kitchen/food bar areas of a football stadium.

The boards are all the old Mem M9 type and still look as good as the day they were put in.

They have been told that they are at the end of their serviceable life and need changing.

This week I have been given the go ahead.

The question is do I need to install surge protection for each board ?

The boards are located all around the stadium and fed from different submains.

I was hoping to replace with Memshield 3 units but might have to change if surge protection is required.

There is no LPS system at the stadium , TNS supply so if required then I am assuming type 2 units hopefully fitted inside the boards .

Spare ways are available in boards to accomodate SPDs.

Advice please
 15 January 2019 10:08 PM
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chrispearson

Posts: 1095
Joined: 15 February 2018

Originally posted by: tillie

I was hoping to replace with Memshield 3 units but might have to change if surge protection is required.

...

Spare ways are available in boards to accomodate SPDs.


In this area, St Mary's stadium (the venue for my 18th Edn success ) seems to be urban, but the Rose Bowl seems to be rural albeit within the Portsmouth/Southampton coastal strip. Daft!

In any event, if I understand the Eaton catalogue correctly, the SPDs are housed in a wee housing which is placed adjacent to the DB. If anybody disagrees, I'd be interested to know - I may need one myself.
 15 January 2019 11:16 PM
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wallywombat

Posts: 96
Joined: 19 October 2018

Type 2 SPDs can be housed within the DB as long as there's space and its mechanically possible (i.e. busbar arrangements etc). The manufacturer may have a procedure or conversion kit for it, judging by youtube videos. European manufacturers seem more geared up for this - presumably they've been in common use for longer.

External housings run the risk of longer cable runs, which are critical to SPD effectiveness.
 16 January 2019 08:05 AM
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Zoomup

Posts: 6117
Joined: 20 February 2014

So, just what valuable and expensive electrical equipment may be damaged by a surge at this installation? I suppose that the main loss would be financial if a lightning strike took out the floodlights at an evening match.

Z.
 16 January 2019 08:25 AM
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briankvedaras

Posts: 42
Joined: 27 November 2002

're what would be damaged?
I suppose quite a variety of systems including communications and PA. A legitimate public safety risk if there was panic, semi darkness, and no communications.
 16 January 2019 08:49 AM
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tillie

Posts: 937
Joined: 03 May 2006

Hi , The distribution boards in question are solely for the food bar/kitchen areas.

Emergency lighting throughout.

The ground has two generators to deal with total blackouts etc.

I was querying that with the introduction of the 18th should I be fitting SPDs to these boards .

I am researching as much as I can about SPDs at the moment but there is conflicting veiws as to whether to fit or not.

There is nothing I can do about the rest of the stadium if there was a lighting strike so is it pointless fitting the SPDs at these locations.

Thanks
 16 January 2019 09:02 AM
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Zoomup

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Bar areas eh? Essential facilities there. If a surge knocks out the kitchens people could still eat sandwiches or cold snacks. Just how essential are these areas?

Z.
 16 January 2019 09:14 AM
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Zoomup

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443.4. Protection against transient overVoltages shall be provided where the consequence caused by the overVoltage could;

(i) result in serious injury to, or loss of human life, OR

(ii) result in interruption of public services and or damage to cultural heritage OR

(iii) result in interruption of commercial or industrial activity OR

(iv) affect a large number of co-ordinated individuals.

Yes, it appears that protection against transient overVoltages should be provided.

Z.
 16 January 2019 09:18 AM
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tillie

Posts: 937
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That is my point , not very essential.

Does the 18th allow me to not to fit SPDs if a risk assessment showed that there is no danger to public or infastructure etc.

As far as I can make out so far is that as long as this is not a single dwelling then SPDs should be fitted unless it can be proven otherwise.

Trying to prove otherwise is beyond my limited intelligence and most people I know.

Regards
 16 January 2019 09:27 AM
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tillie

Posts: 937
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Sorry Zoomup , I posted before seeing your reply.

So it will result in the interruption of commercial or industrial activity.

Looks like I will have to reprice with the inclusion of SPDs.

Surely they can decide if it is warranted for them to accept the extra cost or deem it not to be an interruption of their business and take the chance that they never get hit by lightning , it has not happened in 100 years so why should it happen now ?

I shall post on here about the extra cost involved.

Regards
 16 January 2019 09:31 AM
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Zoomup

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If 443.4 (i) to (iv) above does not apply, that is for all other cases, a risk assessment shall be performed according to 443.5.

If that risk assessment is NOT carried out then the installation shall be provided with protection against transient overVoltages. except for single dwelling units that contain low value stuff, i.e. where the total value of the the installation and equipment does not justify such protection.

Z.
 16 January 2019 09:36 AM
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Zoomup

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Tillie,
if it was me quoting I would spell out both options clearly and in easy to read terms. (1) Without overVoltage protection and (2) with overVoltage protection. Cost for both. Then the person ordering the work can make the decision. Get everything in writing and be upfront and honest. Then undertake the work according to your contract with the club.

Z.
 16 January 2019 09:38 AM
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Zoomup

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Oh, and don't forget that someone has to regularly check the surge protection devices to see if they are still operational, on a regular basis. A visual check of their little self contained indicator flags/lights.

Z.
 16 January 2019 10:51 AM
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wallywombat

Posts: 96
Joined: 19 October 2018

Those SPDs aren't there to protect against direct lighting strikes. They're there to protect against e.g. a strike on LV or HV overhead lines 0.5km away, or a strike to the ground 100m away, or ... etc. Those strikes aren't going to cause everything to explode, but they can cause very brief(*) transients that that can reduce the life of electronic equipment (such as emergency lighting!) by causing brief flashovers between PCB tracks, across capacitor plates etc, which damages the insulation, making further flashovers progressively easier, until eventually the 230V supply itself destroys the device. Then someone will comment about "how these new LED lamps don't last nearly as long as the manufacturer claims".

(*)"Brief" in this case means e.g. a rise to peak in 8 microseconds, then decay to half peak in 22 microseconds - this is the "8/22" test which SPDs are subjected to.
 16 January 2019 12:14 PM
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Cremeegg

Posts: 711
Joined: 13 July 2007

You could always take the view that you designed and quoted last summer so presumably under 17th Amnmt3 - where I believe the wording for SPD's was less prescriptive.
 16 January 2019 02:07 PM
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AJJewsbury

Posts: 17795
Joined: 13 August 2003

There is nothing I can do about the rest of the stadium

Which rather begs another question - generally SPDs need to be part of an overall system to be effective - just putting them into a local DB while leaving them missing from the origin etc will likely mean they're a lot less effective and/or more likely to fail than would normally be the case. (For example with nothing at the origin, the voltage on main bonded extraneous-conductive-parts will likely stay close to earth rather than being brought up to something closer to half the transient's voltage by the origin SPD's - a larger difference that stuff fed from your DB could be exposed to via parallel paths. Occasionally lone SPDs can make things worse - e.g. by drawing the large transient current through smaller conductors (and protective devices) than might have been the case had either no SPDs been fitted at all or a full system of SPDs installed.

I can see the attraction is just putting in SPDs as and when work is needed - so as to spread the costs - with the aim that eventually the whole system will get full protection. But I'm not convinced of the wisdom of that approach. After all we wouldn't start connecting c.p.c.s to exposed-conductive-parts (and certifying those connections as BS 7671 compliant) in the hope that at some point in the future the origin would be provided with an adequate earthing connection.

The usual 'the current version of BS 7671 only applies to new work, not existing installation' I feel needs to be tempered with the requirement that the existing installation need to be adequate to support the new work. I've a feeling that SPDs are adding a new layer to that requirement.

- Andy.
 16 January 2019 05:38 PM
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chrispearson

Posts: 1095
Joined: 15 February 2018

Originally posted by: tillie

That is my point, not very essential.

Does the 18th allow me to not to fit SPDs if a risk assessment showed that there is no danger to public or infastructure etc.

As far as I can make out so far is that as long as this is not a single dwelling then SPDs should be fitted unless it can be proven otherwise.


443.4:

(i) no, it's not a hospital

(ii) no, neither applies

(iii) that might depend upon when it happens, but I don't think that this clause is intended to apply to all businesses

(iv) what's a "large number"?

I think that you do a risk assessment i.a.w. 443.5. That's where the rural/urban bit which I mentioned above comes in.
 16 January 2019 05:45 PM
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JonSteward

Posts: 675
Joined: 04 December 2007

Originally posted by: wallywombat

Then someone will comment about "how these new LED lamps don't last nearly as long as the manufacturer claims".


.


Unpacked today 2 LED wall mounted lights one 50W the other 75W. Manufacturers instructions now mention that they are not to be installed on a circuit which includes fluorescent lighting.
Great ehh!

Also. I was wondering if SPD's can cope with Solar Flares. (seeing that we're overdue a massive one) (see Carrington Solar Flare 1859)
 21 January 2019 08:11 PM
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tillie

Posts: 937
Joined: 03 May 2006

Hi , just a quick update as promised.

The extra cost for installing 4x 3 phase SPDs and 3x single phase SPDs to the proposed new distribution boards is roughly £2400 + vat.

That adds about 30% to my original price.

Ouch.

Regards
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