Identifying MCCB's

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Identifying MCCB's

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moosey86

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Alrighty chaps,

I'm about to go balls deep into an EICR for a big 24 hour food factory that don't have any previous records for anything at all even though it was only built 7 years ago.

I have a bit of a problem with identifying which MCCB compartments on the main panel come from which supply.

There are two main supplies coming into the main panel from two separate step down transformers on the roof.

Unsurprisingly the customer is not interested in me switching off one supply and seeing which circuits stay live and which ones die.

I've tried carefully tracing the busbars in the bottom compartment but it hasn't shed any light for me.

There must be some kind of circuit tracer that I can use but I'm a bit concerned about how reliable they are.

I need to know otherwise my labelling and circuit charts will be incorrect.

Any help would be much appreciated on this.

Cheers guys
 
moosey86 said:
Alrighty chaps,

I'm about to go balls deep into an EICR for a big 24 hour food factory that don't have any previous records for anything at all even though it was only built 7 years ago.

I have a bit of a problem with identifying which MCCB compartments on the main panel come from which supply.

There are two main supplies coming into the main panel from two separate step down transformers on the roof.

Unsurprisingly the customer is not interested in me switching off one supply and seeing which circuits stay live and which ones die.

I've tried carefully tracing the busbars in the bottom compartment but it hasn't shed any light for me.

There must be some kind of circuit tracer that I can use but I'm a bit concerned about how reliable they are.

I need to know otherwise my labelling and circuit charts will be incorrect.

Any help would be much appreciated on this.

Cheers guys
Click to expand...
An installation of that complexity with nil records, someone is pulling your plonker, there must be something somewhere, have you asked the maintenance section? if no drawings are available the engineer in charge wants his backside kicking. Find out who did the initial installation and take it from there.
 
as pete says. an installation 7 years old should have full documentation. go out and kick ---.
 
To be fair the engineer in charge is chasing the contractors that hold the records, but this has been going on for weeks now so it's got to the point where I'm starting to think I might have to accept that I'll have to somehow figure this one out.

If anyone does know of a method I'm all ears [emoji106]
 
How bitchy is that reply Dave.

I didn't get that from the OP description, just sounded like a parallel supply. I took it as an MCCB panel board and the OP was thinking each cable fed different MCCBs. Just my misinterpretation.

I see what he means now though with his description in post 6 of 2 air circuit breakers and it's now clear.
 
moosey86 said:
Now now ladies!

Can either of you suggest anything? Because I'm back there next week and I want to look the dogs knacker's with a solution
Click to expand...

You need to be firm with the hierarchy and demand they get hold of the installation reports, otherwise any investigations on your behalf could result in loss of supplies, I can't believe an installation that complex has no records, unbelievable,
 
I know what you're saying, but if I agreed limitations on the report on the basis that any major supplies will only be live tested to make sure it complies with max zs, cable sizes and circuit breaker sizes would that be enough to say it's been tested given the circumstances?

I know you're saying get the history, I will if I can because that would be problem solved. I'm discussing worst case here tho....in advance just in case it comes to this scenario
 
Ok so it's been confirmed, there are no previous records what so ever to refer to.

This is now a case of agreeing how I'm to go about a full test and inspection and what limitations I can agree with the client.

I'm going to suggest live testing only on all sub main supply's and anything that can't be disconnected due to production. Will this be enough to cover myself if anything was to happen after my signature goes on the whole installation?

After looking further into a few circuits coming from the main panel there are some seriously worrying things I've seen which wouldn't suprise me as to why there isn't any certs.

They have 2 lines of 6 industrial microwaves supplied from 250A IEC 60269-1 fuses straight from the main panel in 70mm SWA. That only just meets the requirements of the current carrying capacity by 1 amp and that's assuming they are laid on the tray without being bunched the whole way to the final points.

Even worse than that is that the fuses in the main panel compartments have been bodged in as the panel has been designed to isolate MCCB's.

They then go straight to the microwaves and don't have any isolators what so ever meaning the only way to disconnect them is to turn off the whole installation.

I know this is serious, and I know it needs to be sorted but the firm seem to be very tight in regards to any situation big or small (Irish run firm!).

I really need the work because I've not long set up so I need to approach this cautiously.

How would any of you more experienced sparks go about this?
 
moosey86 said:
Ok so it's been confirmed, there are no previous records what so ever to refer to.

This is now a case of agreeing how I'm to go about a full test and inspection and what limitations I can agree with the client.

I'm going to suggest live testing only on all sub main supply's and anything that can't be disconnected due to production. Will this be enough to cover myself if anything was to happen after my signature goes on the whole installation?

After looking further into a few circuits coming from the main panel there are some seriously worrying things I've seen which wouldn't suprise me as to why there isn't any certs.

They have 2 lines of 6 industrial microwaves supplied from 250A IEC 60269-1 fuses straight from the main panel in 70mm SWA. That only just meets the requirements of the current carrying capacity by 1 amp and that's assuming they are laid on the tray without being bunched the whole way to the final points.

Even worse than that is that the fuses in the main panel compartments have been bodged in as the panel has been designed to isolate MCCB's.

They then go straight to the microwaves and don't have any isolators what so ever meaning the only way to disconnect them is to turn off the whole installation.

I know this is serious, and I know it needs to be sorted but the firm seem to be very tight in regards to any situation big or small (Irish run firm!).

I really need the work because I've not long set up so I need to approach this cautiously.

How would any of you more experienced sparks go about this?
Click to expand...
tell them straight up.

do you want me to carry on with the testing, the boards and supplies to the machines dont comply.

im guessing there are no emergency stops etc either judging by what your saying.

you could argue due to derating factors the cable is not satisfactory and they should get the original contractors back to bring it upto the required specification at there cost.


its upto you how you want to go from here, personally all industrial should have some form of local isolation.


surely having to isolate the plant just to work on one machine is ridiculous especially in production.
 
I spoke to the NIC about the microwaves (they're actually called transmitters) and they said as long as it's heavily labelled and people made aware what the set up is that's the best I can do without a complete re-design.

As for the cable and fuse size I didn't realise there are isolators inside the transmitters which have their own fuse carriers. I would prefer them to be on the outside but at least I can get to these fuses and drop them down to 200A from 250A. That solves that problem.

Just a quick question on another aspect of the testing.....

The cabling used throughout is predominantly NYY-J. Horrible stuff to work with but I can't imagine it being cheap either!

Question is, type of wiring code? I've been putting A but I did think of using other. If you look at the specs it is PVC/PVC, just not the sort you'd expect if you were to go through the sheets without looking at the install. Not sure about current carrying capacity though, I've been going by standard PVC/PVC so far.

And yes bossian, can of worms indeed! But it's on a day rate so the worms can stay in the can unopened for the time being [emoji4]
 
You initially stated you were doing an EICR and then you have mentioned that you can change the fuse sizes, this is not part of an EICR.
I would concentrate on the inspection and testing and consider the options for repairs at a later date.
The state of the installation you describe means that any repairs would have to be very wide ranging in nature and possibly require significant changes to the supply methods, layout and protection. I could foresee that since they cannot make any accommodation for you in the inspection and testing they will not make any accommodation in terms of repairs either so do not get ahead of yourself just yet.

NYY-J cable is PVC PVC cable and since this section is an irrelevant part introduced by the NICEIC do not worry about it, PVC PVC is correct and using the standard PVC PVC tables will be acceptable for current carrying capacity. Any variation is likely to be of a matter of an amp or two and would vary by manufacturer, though most of them use the BS7671 tables anyway.
 
Cheers Richard, the chief engineer said he wants the observations sorting as I go along. It's all on a day rate so it doesn't matter to me, it breaks up the process a bit too! Prices will go in for the bigger remedials.

One thing I do know is it's getting a full and thorough inspection before any dotted lines get signed
 

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