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Topic Title: Your advice please
Topic Summary: Old, TPN 400A, seemingly unfused.
Created On: 03 April 2013 07:37 PM
Status: Post and Reply
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 04 April 2013 11:21 PM
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Zs

Posts: 2904
Joined: 20 July 2006

Fm, you are on my song sheet with that.

Give or take some calculations and fittings I think that the bolted links could be exchanged for fuses and my head is exactly there at the moment.

I do wonder a bit though, about why the links in the plant room are bolted and if, just maybe, they are bolted links because fuses would not withstand something like maybe the starting up of the old cooling tower? Don't know, but I have a skin tingle telling me to be careful and do the maths.

As you know, I also have a thing going on about acceptable isolation. This one is four floors down. I have now spent at least 20 days of my life in this building and I am not a stupid person. I still get lost in there from time to time. In order to get down from the plant room to the isolator you have to go.... through a passage, down small stairs, through the main kitchen area, through conference room, along corridor, second staircase on the right, down to basement, turn right, find intake room on right. Take the blue staircase by mistake and you will go right down to a dead end before you know about it.

In an emergency I would fall at the kitchen doors in confusion.

Apart from all the code 1 defects which I have not shown you. Do you think this circuit complies? Would you be happy if your wife was the person sent up there to operate the switch of an extract fan, on the other end of the panel each day? In my opinion it is not protected but so far you have helped to protect me from a ricochet reaction. I'll look in on here early doors in the morning as I leave.

Zs
 05 April 2013 01:37 AM
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Martynduerden

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Your welcome to borrow a selection if lugs from my infamous box to assist in sizing cables it goes from 6mm to 1000mm

-------------------------
Regards

Martyn.

Only a mediocre person is always at their best



www.electrical contractors uk.com
 05 April 2013 05:18 AM
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Zs

Posts: 2904
Joined: 20 July 2006

Ha, I pull Martyn's leg about his lug collection and his enthusiasm for it. Not a bad idea though .

Is it the middle of the night? This is the problem with working in Central London. Who am I? What day is it?

OMS called last night and is off today but in your camp Stu.

Thanks,

Zs
 05 April 2013 08:26 AM
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Fm

Posts: 668
Joined: 24 August 2011

Get some fomex or similar material and make it ip2x .
Write a ms/ra for turning on and off the fans, trained staff and all that.

Get a ms/ra for everything,change the links to fuses,.
Decent signage for switch room etc, written shutdown procedure
Happy days
 05 April 2013 12:04 PM
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jcm256

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Zs
I agree that there is nothing as bad as opening a main switch fuse and seeing solid fuse links, or seeing 600amp or 800amp fuses, when you know that the cut-out fuses are only 400amp. Unless you discriminate with smaller fuses than the supply fuses it is pointless and could lead to a problem of power needed for the premises. Fitting the same size of (fuses and type) as the supply fuses is a no for obvious reasons.

From the 15th addition.
The supply authority has a switch or fuse-gear at the installation origin, it may not be necessary to duplicate that means of isolation between the origin and the installation's main distribution point.
(regulations13-15).

See regulation 434.3 (IV) 17th addition.

Isolators are not designed for switching off under load, yours is ok being a main switch or switch- fuse used as an isolator with the solid links. If your isolator is fitted under a bus-bar usually there will be solid bars to the bus-bar so no reduction in conductor size.

Wrote this in a hurry and will remove before the big man comes back, as not sure of your installation original method. Just solid links are not that uncommon in older installations, where the cut-out is near the main switchboard, and don't you check if they are fitted in large fire pumps supply. Switch fuse.

Edited: 05 April 2013 at 12:10 PM by jcm256
 05 April 2013 09:48 PM
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Zs

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Thank you for that jcm and I agree. I think leave it, it is valid and OMS doesn't bite too bad.

Something happened today which changes the entire perspective of this place and my report. I think I should tell you.

A bar area on the third floor, has its own DB from its own drawer in the intake room. Earlier this week I had the drawer out for Z tests etc.

During the week one of the other DBs, on the second floor, has been switched off for changing and has been off for three days.

So, nobody commented on half of the third floor bar being off because they thought it was part of the other work. Until 6pm this evening, deep joy.

Yellow phase had not engaged into its slot in the drawer when the spring handle sprung shut.

It has now, but who knows how snugly? IMHO this is evidence that the control panels have come to the end of their useful lives.

Thanks for yours jcm and I'm looking at the regs right now.

Zs
 05 April 2013 10:57 PM
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Fm

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When we rack out gear, we always checked all the phases were correct after re energisation.
Doesn mean its near its shelf life, just one of these things, happens with mem glasgow units as well
 05 April 2013 10:58 PM
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Fm

Posts: 668
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When we rack out gear, we always checked all the phases were correct after re energisation.
Doesn mean its near its shelf life, just one of these things, happens with mem glasgow units as well
 06 April 2013 10:00 AM
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dlane

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Originally posted by: Fm

When we rack out gear, we always checked all the phases were correct after re energisation.

Doesn mean its near its shelf life, just one of these things, happens with mem glasgow units as well


Switchgear of this type requires general maintenance and cleaning from time to time especially if it has infrequent operations.

Over time being stationary in the same position and with the heat from the current flowing through it, the contact and mechanism grease will harden and prevent operation of it. Dust entering into the cubicle and settling on the grease adds to this. Stripping, cleaning and lightly regreasing everything will restore it to full operation. I know of switchgear over 50 years old of similar construction and still working well.

The switchgear can also be exercised on a regular basis to help prevent it seizing up.

If there are doubta about it making properly then a thermography window can be fitted and an IR camera used or kill the whole board and check contact resistances if possible.

When we isolate devices of this nature that has no integrated system for a padlock we use a cable lock system or we manufacture a bespoke locking mechanism. As long as the lock prevents the cubicle from being pushed back fully into position it will be fine.

Kind regards

Donald Lane
 06 April 2013 10:43 AM
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alancapon

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There was a similar issue of lack of maintenance at a water treatment plant in the UK last year. The handle on the switch-fuse was moved to off, but once the cover was opened, the three bolted fuses all remained live.

It seems that the mechanism had failed (out of sight) due to the operating shaft not being straight, and lack of greasing on the gears of the mechanism. In this instance, the gear moving the mechanism had very little left of its teeth, because the annual greasing recommended by the manufacturer of the switchgear was not carried out / was not carried out correctly.

Fortunately the electrician tested the fuses after opening the switch. This could so easily have had a different outcome.

Regards,

Alan.
 06 April 2013 12:21 PM
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Zs

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The last three posts are very helpful to me thank you. fortunately I am a long way from writing the report for this place, which which will accompany the EICR.

I have just done a bit of googling on the subject of maintenance and I wonder if it would be approriate to suggest a visit from a GE engineer by way of casting an eye over a non-cared-for system and advice. GE being the logo on the switch drawers. It is true that they suggest a very long life for their switchgear.

The lack of locking worries me.

I am not desperately keen to suggest the usual resonse of rip it all out and as far as I can see the main cabling between incomers and distribution areas such as the plant room is very sound. I am also wondering if the cupboard in the plant room could be adapted to include a switch. It needs new doors anyway.

Thanks for this, it opens a possible avenue for some changes which, whilst they're still going to cost a fortune are going to cost less than full replacement of all their switchgear.

I also think they need a full-time proper decent electrician in there for a couple of years. They are coming round to that but it wouldn't be me (offered twice now).

One day I'll bring this thread back up and tell you what was done.

Zs

Edit, Donald that is the third time this week that thermal imaging has come to mind. I've been giving it some serious thought and I am sorely tempted to put it on my list of things the get a handle on. I'm on the auto cad learning curve at the moment but I think it should be next. All part of operation 'off the tools' you see. Could be of use to the geek agency I work for too.

Edited: 06 April 2013 at 12:33 PM by Zs
 06 April 2013 07:26 PM
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dbullard

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Originally posted by: slittle


Old, yes, Rough by todays standards, yes but it's old.

Stu


Stu,

I wish some of the "Newer" stuff that I come across was as tidy as this, I will be turning of a complete "Depot" next weekend, and I fully intend taking photos of the "Dross" installed some of it is probably 1960 at a guess possibly a little earlier.

Zs's job is tidy mine is a "Badgers Ar#e".

Regards

Daren

-------------------------
..... Dont pee in my pocket and tell me its raining ......


www.quest-electrical-sw.co.uk

Edited: 06 April 2013 at 08:46 PM by dbullard
 06 April 2013 07:52 PM
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Fm

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Im going to get. Thermal imaging camera next year,
Properly for finding 'air' leaks etc. but will use it for a bit of hot spot work as well.
If anybody is using anything, they recommend, let me know, used the fluke series of cameras before.
Standard of workmanship and its decline is due to price work, staff who doent care, and lack of supervision, lots more i could add, but on a phone
 08 April 2013 01:07 PM
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OMS

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Looking at the pics, it's old "Allen West" fused switch assemblies put together in a (Form 3 ?) assembly to create a partially type tested switchboard.

Lack of lockable isolation was never a problem - you just took out the links

Lack of protection at the incoming device is perfectly normal (you are making a demand on the DNO fuses as allowed under ESQCR and the supply regs before that.)

I wouldn't be happy about what appears to be flex floating about the fused switch chamber and from the photo, I'm not clear how the neural terminates either.

The supply to the HVAC appears suspect in the sense that the client cable extends some distance without protection - either this was agreed on day 1 or yo have fuses swapped out for links at some point in the past - cooling system loads as you suggest might be the culprit.

My advice would be to undertake a comprehensive characterisation of the switchboard to highlight the problems and provide that as an addendum report to the EICR - ditto for the HVAC MCC.

I think you do have to face the fact that you have 50 year old switchgear though - it doesn't have any serious deficiencies such as manual dependant switching - but if it does fail, catastrophically, how would repair be managed - I'm guessing it couldn't.

The phrase financially, economically and technically expired springs to mind.

Regards

OMS

-------------------------
Failure is always an option
 08 April 2013 06:12 PM
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OMS

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Originally posted by: Fm

Im going to get. Thermal imaging camera next year,

Properly for finding 'air' leaks etc. but will use it for a bit of hot spot work as well.

If anybody is using anything, they recommend, let me know, used the fluke series of cameras before.

Standard of workmanship and its decline is due to price work, staff who doent care, and lack of supervision, lots more i could add, but on a phone


We use, for both building problems and electrical imaging, the Flir 400 and 600 series IR cameras. Excellent pieces of kit with everyting you need to do a serious job.

They are not cheap however (sit down first if you google for a price) and you can get away with a lot less in terms of equipment quality. The alternative is to rent one when you have enough work for it.

Just remember that IR thermography is just another tool in the armoury for diagnostics of a problem - it still won't replace a functioning brain backed up by the mark 1 eyeball, sense of smell and touch and an idea of the problem trying to be either identified or solved.

Equally, if the switchboard (for example) isn't set up with thermal imaging screens you can spend an awful lot of time and money making the switchboard IR compatible when simple common sense would have told you to consider swapping it out anyway.

Take the case of the OP - it's a pair of 400A incoming services. A new switchboard (or probably a panel board actually) swapped out over a weekend as phase 1 of the likley remedial works wouldn't be a big cost given the longevity of the investment - particularly if there was room to erect it without tearing out the existing straight away.

A form 4 Type 2 board, 2 x 400A incoming switchfuses, a stack of outgoing MCCB or switchfuse assemblies . Say 50KA fault level - circa £12K delivered to site - add say £8K for site works, and away you go. Put that to the market and it'll knock 15% off.

Regards

OMS

-------------------------
Failure is always an option

Edited: 08 April 2013 at 06:34 PM by OMS
 08 April 2013 08:27 PM
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Martynduerden

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Originally posted by: OMS


The phrase financially, economically and technically expired springs to mind.

Regards

OMS


I suspect the client won't agree with the "financially & economically" bit! I think you need funds to change these things!

Like you said in another post an adjacent room for a new panel would be ideal....

-------------------------
Regards

Martyn.

Only a mediocre person is always at their best



www.electrical contractors uk.com
 08 April 2013 08:31 PM
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Martynduerden

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That's a cheap panel OMS I seem to recall paying 16k for a 1600A single supply unit. You can send me the details if you like - no use at the moment but who knows in 6 months I may! ( nothing to do with the Op)

-------------------------
Regards

Martyn.

Only a mediocre person is always at their best



www.electrical contractors uk.com
 08 April 2013 09:43 PM
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slittle

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Originally posted by: OMS


The phrase financially, economically and technically expired springs to mind.



Regards



OMS


Can't you tell OMS tends not to spend his time on the tools these days... We would tend to use the phrase "it's kn...er.d"

Stu
 08 April 2013 10:02 PM
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UKPN

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"OMS tends not to spend his time on the tools these days"

thank G"D for that, its a nightmare just on the forum, think what he would be like inspecting our 50 year and older mains and earthing systems and putting us right!

Regards.
 08 April 2013 10:21 PM
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Zs

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That's not kind UKPN. I take it from that you haven't yet met OMS? He's a big enough man to be able to shrug that last comment off though. OMS, I bought you a big box of jelly babies today, will get them to you.

Stu, I tend to say 'I'm afraid it's buggered. That's a technical term you understand...'

Been a difficult day there today but the on site work on the EICR is nearly done with just two days to go. 45 pages of test results and 15 pages of observations so far. God bless you Rutts, for creating the most useable certificate software in the universe. I would not have been able to go through this many circuits without something user friendly. Off to bed.

Zs
IET » Wiring and the regulations » Your advice please

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