Welcome Guest! The IOSH forums are a free resource to both members and non-members. Login or register to use them

Postings made by forum users are personal opinions. IOSH is not responsible for the content or accuracy of any of the information contained in forum postings. Please carefully consider any advice you receive.

Notification

Icon
Error

Options
Go to last post Go to first unread
prads  
#1 Posted : 11 June 2019 11:31:41(UTC)
Rank: Forum user
prads

Is there any standard/reference which mandates fire protection of cable trays, even if the cables within it and all accessories and components are fire rated? Is it either of them should be fire protected or both needs to be fire protected?

Seeking advise and opinions.

Regards,

P

Ian Bell2  
#2 Posted : 11 June 2019 12:20:29(UTC)
Rank: Super forum user
Ian Bell2

It depends - what power supplies are these cables supplying?

Its difficult to answer such questions because you don't supply enough information to technical issues.

What industry? How critical is loss of power from these cables.

Has diversity/independence of supply been been considered?

Are you protecting against external fire risk from surrounding processes?

If this is a new project/design - you should have a fire protection policy to cover what services need fire protecting and how it will be done.

Roundtuit  
#3 Posted : 11 June 2019 12:30:11(UTC)
Rank: Super forum user
Roundtuit

Building Regulations Approved Document B, in particular references to compartmentalisation as cable trays often "vanish" through the walls between/inside buildings. Whilst the materials may be fire resistant the gap caused by their routing breaches the fire compartment.

Also BS 9999 Code of practice in the design, managemnt and use of buildings

Ian Bell2  
#4 Posted : 11 June 2019 12:35:10(UTC)
Rank: Super forum user
Ian Bell2

API 2218 if you want another industrial fire protection standard.

Greater clarity in your queries would be very helpful

prads  
#5 Posted : 11 June 2019 14:52:48(UTC)
Rank: Forum user
prads

Thanks for all the replies. This is for a new construction activity within and existing petrochemical plant which is in operation. While our standards are requiring fire trays to be fire rated for at least 30 mins, the contractor is seeking deviation claiming that the cables and all other accessories and instruments that is going to be in the tray are already fire rated for 30 mins and hence no value addition by making the tray fire resistant. The question is whether is that a practice and if the cables are fire rated, do we need to insist on cable tray fire protection. Regards P
Ian Bell2  
#6 Posted : 11 June 2019 15:08:15(UTC)
Rank: Super forum user
Ian Bell2

For a petrochemical site then API2218 is what you need.

This seems to be a design issue, your contractors should build as instructed by the designers.

For the project you should have a basis of design document, outlining the standards to be followed for the project.

Your Client may also have there own design standards, most of the larger oil/petrochemical companies do and specify what they want - which you hint at.

Have the project completed a HAZID & HAZOp study for the design, how crticial are these cables?

If in the UK, the Principal designer should also be interested in this issue - as part of CDM PD duties

thanks 1 user thanked Ian Bell2 for this useful post.
billstrak on 13/06/2019(UTC)
Roundtuit  
#7 Posted : 11 June 2019 15:09:28(UTC)
Rank: Super forum user
Roundtuit

The architect/designer will have drawn up the scheme with a specification of materials to satisfy the regulations and standards

Contractors "down specifying" to boost their profits is something that should always be avoided, and now you have been forwarned this is a route they are considering make sure it gets a very competent inspection before sign off acceptance

If in doubt refer to the person whose professional indemnity you may later be relying upon

prads  
#8 Posted : 12 June 2019 03:31:05(UTC)
Rank: Forum user
prads

Yes specifications are drawn up in the contract documents, but they are actively reviewed and risk based decision is taken to revise. Hence, the question. Is there any technical justification for having both the trays and the components inside the tray to be fire rated? Or either of them could be fire rated? The purpose is the withstand an external fire for certain period while the plant tries to recover with less damage.

Appreciate your thoughts on this?

Regards,

P

Ian Bell2  
#9 Posted : 12 June 2019 07:56:55(UTC)
Rank: Super forum user
Ian Bell2

So construction contractors are altering what designers have specified as being required to build/maintain the plant.

As previous, you need to go back to the Basis of Design - that will indicate the minimum design standards for the project.

Also any process safety HAZOP studies or Fire & Explosion reports to determine what fire scenarios have been identified and potentially the types of fires that may develop e.g. pool fires, jet fires. That will guide you as to the type of passive fire protection required and where passive fire protection should be applied to primary structures or around vital power supplies.

Glad I'm not working on your project, if construction contractors are altering specifications? if that is happening. 

chas  
#10 Posted : 12 June 2019 08:00:20(UTC)
Rank: Super forum user
chas

The fire service might not thank you if you put non fire resisting cable trays along escape routes. There have been instances where fire fighters have got tangled up in cables that have dropped from plastic cable trays/trunking in a fire. If you scroll to the bottom of the article in the link below you will see what I mean.....

https://electrical.theiet.org/wiring-matters/issues/56/protection-against-fire-the-fire-officer-s-view/

I guess it all depends where your cable trays are going to be located and the risk of entanglement in the event of a fire situation.

thanks 1 user thanked chas for this useful post.
billstrak on 13/06/2019(UTC)
Ian Bell2  
#11 Posted : 12 June 2019 08:59:06(UTC)
Rank: Super forum user
Ian Bell2

chas

By the sound of it, there is more to this than entanglement. The poster has sais this is on a petro-chemical site. No-Uk I think.

It hasn't been established what the cables provide power to  - they might provide power to the Emergency Shut Down systems, for example.

Until that is known, its not clear if the cables/cable trays need to have passive fire protection applied/specified.

prads  
#12 Posted : 12 June 2019 10:04:52(UTC)
Rank: Forum user
prads

Thanks Chas for your reply. I guess thats very much it. Irrespective of what type of cables or its intented purpose, there is a risk of trays failing and cables and all accessories contained in the tray drops down create a potential hazard not limited to emergency personal. 

These trays will contain cables for rosov/esd/esps etc. However, they all are fire rated.

Ian, thanks for your reply. Your concern that contractor is changing the specification is a misunderstanding. What I meant is the design basis is reviewed and if required it could be revised by the Owner of the plant and not the Contractor.

Regards,

P

Salvar  
#13 Posted : 14 June 2019 22:21:58(UTC)
Rank: Forum user
Salvar

The Shirley Towers fire in 2010 (in which it was ruled that two firefighters died from exposive to excessive heat after becoming trapped in cabling that had fallen from plastic trays) led to the requirement for cables trays to be made of metal rather than plastic.  The question then becomes how long the tray assembly will stay in place when exposed to fire.  This doesn't necessarily mean that it is fire-resistant but it must maintain structural integrity.

Are the contractors suggesting that cables will remain in place without the trays?  If so, this would suggest that, as well as being adequately suspended, they are under tension and/or have an inherent structural stiffness that would resist sagging.  Seems to be a bit of an ask when the trays would do the job.

To reiterate others' comments, it may not be a duplication of fire resistance that is at issue, it may simply be how the cables will remain suspended under fire conditions.

If I have misunderstood, my apologies.

Regards

Steve   

Users browsing this topic
You cannot post new topics in this forum.
You cannot reply to topics in this forum.
You cannot delete your posts in this forum.
You cannot edit your posts in this forum.
You cannot create polls in this forum.
You cannot vote in polls in this forum.