Industrial earthing problems - again deadly

[Inteificio]

Hi,

As you might remember from the last thread, I'm now working in a factory where they used to contract out the electrics.
Unfortunately they used a negligent installer, so I have to fix it with no expenditure or time taken =-)

This problem is one of the main tank rooms.

There are a selection of stirring tanks, and a pump at the bottom.

The feed to each tank and pump is separate, with it's own isolator.

Each circuit has it's own overload.

Sounds alright so far, unfortunately:

There is no CPC to any of the tanks (SY sheath does not count in my books)
There is no equipotential bonding anywhere (this room is a high risk environment, it needs it!)

The only protection for short circuit or earth fault (apart from the overload which I assume will not trip in time) is a lone D50 breaker that covers everything.
All wired in 1.5mm (fun for a D50 breaker).

So my top priority is to make it safe, then legal.

I am putting in-line fuses for all to get the SC and EF protection, but the CPC problem is an issue.

I have read guidance note 8, regs and OSG and it is so vague.

If I had designed it each circuit would have it's own dedicated CPC, but pulling out all the SY and refitting would not be allowed, and strapping CPCs to the side of the SY has been managment vetoed too.

So my idea is to link the tank CPC to the Pump to allow it to carry the fault current. On the link I am also bonding it to a metal frame that goes to near the board and that is connected too.

The way I see it is any fault on the motor will dump current through the pump CPC and the parallel path through the steelwork (Steel CSA 40mm2).

This is a photo of what I have done (I'm sorry it looks so bad, we have damaged boxes and no budget to replace them or even get stuffing glands!)

 

[Inteificio]

So apart from the comments of 'that is so sloppy' Is there any advice that can be offered?

Is this the best way of doing it, is it legal?

 

[Engineer54]

Hi,

As you might remember from the last thread, I'm now working in a factory where they used to contract out the electrics.
Unfortunately they used a negligent installer, so I have to fix it with no expenditure or time taken =-)

This problem is one of the main tank rooms.

There are a selection of stirring tanks, and a pump at the bottom.

The feed to each tank and pump is separate, with it's own isolator.

Each circuit has it's own overload.

Sounds alright so far, unfortunately:

There is no CPC to any of the tanks (SY sheath does not count in my books)
There is no equipotential bonding anywhere (this room is a high risk environment, it needs it!)

The only protection for short circuit or earth fault (apart from the overload which I assume will not trip in time) is a lone D50 breaker that covers everything.
All wired in 1.5mm (fun for a D50 breaker).

So my top priority is to make it safe, then legal.

I am putting in-line fuses for all to get the SC and EF protection, but the CPC problem is an issue.

I have read guidance note 8, regs and OSG and it is so vague.

If I had designed it each circuit would have it's own dedicated CPC, but pulling out all the SY and refitting would not be allowed, and strapping CPCs to the side of the SY has been managment vetoed too.

So my idea is to link the tank CPC to the Pump to allow it to carry the fault current. On the link I am also bonding it to a metal frame that goes to near the board and that is connected too.

The way I see it is any fault on the motor will dump current through the pump CPC and the parallel path through the steelwork (Steel CSA 40mm2).

This is a photo of what I have done (I'm sorry it looks so bad, we have damaged boxes and no budget to replace them or even get stuffing glands!)

You know, i know, and everyone here knows (hopefully) that what your contemplating as remedial work isn't acceptable, and wouldn't comply with any standard that governs such industrial installations.

Doesn't matter what your employer might have to say or not say, they have statutory responsibility's to abide by, costs just don't come into this equation.... Any accident/fire or whatever and your companies insurance company will survey the installation as a whole, and in all likelihood remove any cover afforded by them due to electrical installation not meeting minimum standards and probably the HSE people will then be suing the ground from under your companies feet!! lol!! You wouldn't be fairing very well in that situation either, ...so be warned!!

If these poorly installed electrical installations have been installed by an outside electrical contractor, then your company should be making representations towards this company to rectify any work that doesn't meet minimum electrical safety standards/regulations

 

[Sharpend]

Why do 'we' always feel obliged to put everybody else's mistakes right? Then try and justify the shortcuts that we take to do it?
why not stand up and say this isn't right and to put it right is going to involve this. I dare say the management wouldn't have a monkey of an idea of what is right or wrong, so someone must have told them what Could be done to make it safe even if it technically isn't safe or right,why give them the option in the first place, it is inevitable that they will always choose the cheapest!
do it right or don't do it at all, anything less than right makes you a cowboy in my book.

 

[snowhead]

What are the tanks made of?
What is the pipework connected to them made of?
Are the pumps submersible / double insulated?

 

[Inteificio]

Thanks for the obvious remarks Sharp.

As it is, the company is aware the site is dangerous. I have done a full inspection, and filed a formal report.
They do not want me to fix it.

I am slowly repairing it when the boss isn't looking, but I am not paying out of my pocket for the parts.


As for this being against regs:
That was my question, I have read the regs and it does not seem in opposition (apart from stuffers).
It is not a standard install, but what exactly is the issue?

My understanding is that each circuit requires a designated CPC, and you are allowed to share this CPC.
I am using the CPC of an attached circuit.
In addition, I am providing a very good parallel path to help out.

 

[Inteificio]

Snow,

Everything is metal from the '60s.
There are two types of pipe. There are stainless jacketed pipes for pumping the products (and keeping it warm). Copper pipes feed the water to the jackets.
The electrical continuity of the stainless pipes is poor due to thin wall and lots of dirty screw fittings. The copper pipes are to be bonded as soon as the fittings arrive.

Pumps are external to the tank. Metal pipes connect tank to pumps and on

 

[Deleted member 72666]

I feel for you, but you must document your concerns and present them as a report on what you think is the minimum required to make things safe, then organise a meeting with the safety committee if you have one (sounds very much like you don't) or even the MD to discuss the report and get them to officially recognise the problems in writing (email is great for this) The minutes for these meetings are a great way of having documented proof of concerns being raised which will be your friend if the ***p hits the fan as the Duty Holders are dragged through the courts and as in most cases it'll be your word against theirs.

 

[Inteificio]

I think I must be phrasing my question poorly.

I have informed management, everything is documented. Their formal answer is NO.

What I am trying to do is make the above install safe but am unclear on regulations on non-standard earthing.

It is standard practice to have a separate CPC leading back to the main board for each circuit.
The regs however permit sharing of CPC (the only time I normally see this is with an earth tape running around a factory that all circuits use).

So what are the rules on this?

Once I have the fuses in, using the CPC of the adjacent circuit should be safe. Regs only require the fault path of a shared CPC to take the fault current of the worst circuit at once (not both).
That CPC can comfortably take the fault current, the supplementary bonding makes my earth return far in excess of requirements.

So what I am asking is:

1: Is this allowable, and if not, why not.
2: Are din rail fuses for each line the best approach for covering short circuit and earth fault? - Might think about a large RCD too.
3: Does anyone with relevant experience have any suggestion and advice on how to make the install better - taking in to account I am not allowed to pull new cables.

As for advice on how to deal with my company, although the concern is appreciated, i've got myself covered and have no budget or time allocated.

I'm only looking for advise on the technical side, and in that regard, I'd really appreciate anything you guys have to give. Someone must know more about this than me!

 

[Farmelectrics]

keep a copy of the report its your employers responsibilty to make the installation safe why are you even bothering putting it right

 

[Darkwood]

You shouldn't borrow a cpc off a dedicated final circuit but you can have a common cpc to multiple circuits i.e. a trunking system. Consider the circuit the cpc was borrowed from was disconnected it would make the other circuit a danger which is a situation you shouldn't have. Don't get confused with earth conductors for more than 1 circuit where often found in sub-mains supplies where the earth is affording protection of the several circuits connected to the sub mains.

 

[Sharpend]

Whilst I admire your commitment and enthusiasm, I would be very concerned about leaving myself open to being the fall guy should things go badly wrong.
If the management are not prepared to entertain your report then so be it on their head.

 

[KAS1]

Is it my eyes or I am correct in stating that the sy cables are not supported throughout their length (on the tray and also dangling from the isolators) ? also it looks like the IP rating of the isolators have been breached with the earth cable shoved through a blind grommet (top entry at that) are the locking mechanisms broken as well? Is that a cable laying across the floor? If you're going to leave that mess, run the cables in some galv trunking (use that as your cpc) lol better still rip it out and use swa, if they're paying your wages to be there anyway, its only the cost of some materials job done.

 

[Guest55]

so if your company doesnt want you to do the work......
or the client / site owner wont pay for the work anyway........
why the hell are you bothering with someone elses mess ?
sorry , really dont understand your objectives.

as for the issue of plant wired in 1.5 with no cpc all sharing a single D50....
forget it , the whole design needs re thinking.

 

[Engineer54]

I think I must be phrasing my question poorly.

I have informed management, everything is documented. Their formal answer is NO.

What I am trying to do is make the above install safe but am unclear on regulations on non-standard earthing.

It is standard practice to have a separate CPC leading back to the main board for each circuit.
The regs however permit sharing of CPC (the only time I normally see this is with an earth tape running around a factory that all circuits use).

So what are the rules on this?

Once I have the fuses in, using the CPC of the adjacent circuit should be safe. Regs only require the fault path of a shared CPC to take the fault current of the worst circuit at once (not both).
That CPC can comfortably take the fault current, the supplementary bonding makes my earth return far in excess of requirements.

So what I am asking is:

1: Is this allowable, and if not, why not.
2: Are din rail fuses for each line the best approach for covering short circuit and earth fault? - Might think about a large RCD too.
3: Does anyone with relevant experience have any suggestion and advice on how to make the install better - taking in to account I am not allowed to pull new cables.

As for advice on how to deal with my company, although the concern is appreciated, i've got myself covered and have no budget or time allocated.

I'm only looking for advise on the technical side, and in that regard, I'd really appreciate anything you guys have to give. Someone must know more about this than me!

''It is standard practice to have a separate CPC leading back to the main board for each circuit.''

Do you really need to ask this question?? Your talking about multicore cables are you not, so the answer is Yes!!

You don't borrow other final circuits CPC's, and you don't tap of the structure or add-hock steelwork for your CPC connection either!!

As has been already explained, an electrical metal containment system is not the same as add hock steelwork. Any earthing related to that metal containment system, is made/installed to be electrically continuous. In such cases no separate final circuit CPC's need to be run within such a system and any earth connection at points of termination, can be made directly to or via that electrical metal containment.

Your trying to find ways around the problems your encountering, looking for wording within BS7671 and OSG's. Unfortunately your not going to find any. The add hock steel work does not meet the same requirements as an electrical metal containment system, so don't use them to provide a CPC connection to non compliant cables.


As others have stated, this is now not your problem, you have made representations to the company about your concerns, it's now firmly in their court. You could actually be making things worse for yourself by conducting these alterations to the existing installations. So leave it alone and let your employer take the responsibility for their lack of action and interest, after all they are taking the profits!! lol!!