huge scale pir thoughts

shop deals on amazon
Shop deals on ebay
armeg
Advertise with us
Talk Electrician Forum

Help Support Talk Electrician Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.
kme

kme

Fridge Keyholder™
Supporting Member
Joined
Mar 7, 2008
Messages
9,984
Reaction score
0
Location
In the office again.
Hi all

As some of you may remember, I`ve been doing some works for a large national hotel chain.

Now I`ve got the option of a PIR (5 yearly jobbie) on a 15 storey, 200+ DB`s place up north.

I`ve done a fair few PIRs, but never anything of this size. Thoughts / tips / timeframe???? Puhleeze?

NB - 2 no. 3phase supplies. (parallel). Protective devices not verified. supply conductor CSA 400mm - 1200A per phase.

Apparently, the last guy there couldn`t find the main bonds to water / gas??!!!!. Wouldn`t think they`d be hard to see (if they`re there)!!

 
I cannot give you any advice on this stuff but it does sound like a very interesting job KME. Assuming you do the work remember to try and get a few photos for the forum an give us some updates of the sort of things you find on jobs of this size. Good luck with your evaluations of timescale.

Doc H.

 
The bit that puzzles me is two 3 phase supplies in PARALLEL

So how does that work then? Two supply heads each with their own fuses then strapped together in parallel? that doesn't sound right.

I can see multiple supplies, but surely it would be split with each supply feeding part of the building, but with earth's cross bonded.

As for testing, well it's just the fact there is a lot of it. I assume there are a lot of submains, presumably single phase db's, so those you just test like any other installation.

The fun bit comes when inspecting / testing the 3 phase distribution boards. That's going to be some big stuff. A major problem you will have is powering down parts of the installation for testing. I would expect the hotel to be open all year so trying to get their agreement which bit you can shut off and when could be a major pain.

I wonder if they would accept a limited scope test on the 3 phase stuff to avoid powering it down? something to discuss with them.

I know when doing minor repairs on commercial stuff, it can take longer to get the power off than it does to actually do the repair, having to go round the office, get everyone to shut down their computers, then wait until they are all off before you can turn the power off.

 
Martyn,

Last job I looked at with supplies this size was an industrial!

May have 11kV sub on site?

If so bonds may be done to there.

Prob an acb main switch.

Either large panel boards on the front end or a bus bar setup.

Poss even main bus bar risers?

If so themal imiaging may be an advantage.

Measuring r1 & r2 with a bus bar system and a normal meter is probably not worth doing.

You would need a ductor tester to get an accurate reading.

I would strongly suggest discussing the requirements with the properties/facilities engineer & or H&S dept of the end customer.

Also, judicious use of GN3 and sampling.

Would you be doing remedial work as you go along?

I would suggest:

Start with an audit of previous docs.

Then start the inspection at the intake.

Next the basement if not one in the same.

I WOULD next verify the main bonding.

Full visual of all areas.

Check circuit ID's etc.

Covers off all boards to inspect.

If possible I would 100% do all guest rooms, this should be doable as they will not be fully occupied t all times.

I would suggest that all RCD

 
Last edited by a moderator:
id imagine a DB would feed a few rooms - in which case you could arrange time to get access to those rooms, test, and also get submain to it at same time. then move onto next board. if a submain feeds a board which then feeds more submains, then you may have problems with isolation, so may be live testing only

if you can get more info, may be worth estimating time per DB & submain, and adding all together

 
Trying to do PIR at a place like that would be full of pitfalls if you try to quote.

Access to rooms will be hit and miss, Testing catering eqipment, say, in between them using it. Give them an hourly or day rate and explain the reason . Then I recommend doing a F/bd at a time . The paperwork will be of great magnitude (means a lot,Specs)

Can't think of anythink more boring TBH but it pays the bills.

Deke

 
Deke,

Actually I don't mind PIR's, I think that this would be quite an interesting job.

Sad I know!...

:coat

 
It should be a well paying job, Paul, not to be sneered at. We just did a PIR at a regular customer's print works , we did remedial works first as we know the place, then he says there is only

 
The post by netblindpaul has just reminded me of why this is the best forum for electricians (and vets).

Some very solid and sound advice there and worth a scooby from me.

Well done mate.

 
Sometimes when PIRing a big place, you some of the bonding has to be a limitation because no one on site actually knows where the incomming water service is! - its not ideal but you can spend a little time looking for it then you have to move on!

I did a hotel a little while back (well former hotel, was student halls), the rsisdents were advised that power could go off at any time for a few minutes, and that I'd be visiting the all the rooms (with a knock on the door if they were in, building master key otherwise), my method of working there was to visably inspect a room, open a few fronts, loop test sockets, then I'd pick an earth up from the sockets and continuity test from that to metal class 1 wall lights and switches in the room (found loads unearthed!!), if earth was sound to lights, would loop test that and not it down, when I came to a DB, I'd open it up, give it a good visual inside, get Zdb and PFC, test any RCDs at it, and then as long as I could isolate db (most of them on this job :) ) I'd isolate it, prove it dead, link phase(s) and neutral (and open neutral link if applicable), megger it all to earth (first at 250v and then do it at 500v only if it was clear), then I'd do end to end of ring final circuits, before putting it back together and re-engergising

This apprach seemed to work well, I had abut 800 defects at the end, and the whole document the customer receieved was 180 pages long, 100 of pir forms, 80 of typed report (faults and summery).... and got a lot of stuff the previous pir missed going by the remedials I could see ...the 4mm earths added in YT2 to some fittings (shame they only got a very small number of them!!)

 
On the subject of PIRs , I have seen quite a few done by others, where they have only done a visual , putting stickers on ,say, a switch that needs a blind grommit .
Click to expand...
On any PIR the visual is probably the most overlooked.

On large installations it is far easier doing a thourough visual, which can show up some code 1 and 2's, which until they are "fixed" it would be pointless testing the whole electrical installation.

Some companies will insist on a formal visual before any testing, the remedial work thrown up from the visual is carried out, and then a formal test is followed.

It works out cheaper than the whole hog from the start.

I am doing three connected units at the moment where walls have been built to divide the units, but the fire alarm from one unit is powered from another, the roller shutter doors are the same, and one db is shared by all 4 units.

Now that one hell of an headache to sort out.

 
Some excellent comments & insights there - thanks all ;)

I think Paul is on the money, r.e. supply - I`m expecting on site 11KVA tranny.....

Issues are: the 100% submain & 20% final is from the consultants; who will prob. also give a timeframe they`ve allowed (though they`ll usually play ball).

But....I won`t be able to see the job until I go to do it - its 200+ miles away.

And yes, GH, I though it deserved a scoob, too :)

From the previous PIAT, there are many different subs, most seem to be fed in SWA. as for rooms / boards - I`ve only got to page 234 so far; and we haven`t come across a board serving any guest rooms yet.

Interesting - Most definitely.

But, if I`m honest, a tad scary too......

KME

 
Often with limited PIRs, it is often stipulated that a percentage will be inspected, unless there are defects found which will then entail a more in depth inspection.

Another thing to determine, is how many points there are in each room.

If for instance each room has only one socket-outlet, and one light. Would you be expected to test every 5th. room (20%) or each room (100%)?

 
AFAICT mate, it`s 20% of final ccts - my choice which ;) .

I could do 1 cct in five, or do a whole board. The actual PIR doesn`t bother me; just the pure size is a bit daunting,,,,,,,

 
I have never had any thing this big but always think that however big the job is, it is really only alot of small units added together.

Suggest just breaking it down into smaller size sections and taking a day at at a time.

 
AFAICT mate, it`s 20% of final ccts - my choice which ;) .I could do 1 cct in five, or do a whole board. The actual PIR doesn`t bother me; just the pure size is a bit daunting,,,,,,,
Click to expand...
if you dont mind me asking, how will you fit this in around other work? or would you put other work off? or use subbies?

 
I`ll schedule the time out in the diary, and go up there for the duration, having my customers either finished up before I go, or booked in for when I return ;)

Tim - Yes, I know what you mean, and like so many other things, theoretically its great. In practice, things have been moved, (as someone else said previously) - you can spend more time running around the building than doing anything - no time is being allowed for tracing unmarked circuits, but there has to a certain amount[i.e. verification of which phase an SP board is coming from....]

KME

 

Latest posts

Top