Routing Meter Tails Through Cavity? Thermal Bridging + Fire Protection

[LOYDE]

Hi all,

Am new to the forum so hope I've posted correctly.

System 1966 lead TN-S

Am about to move cu to new location, concrete cavity wall with meter box on outside.

Intend to route 25mm tails + 16mm Main bonds through wall via 50mm steel trunking to cu and main earth to met (in meter housing).

Am happy this will comply with additional protection regs but am worried about thermal bridging of the cavity and the potential for a fire to whip up/or through the cavity.

Would it be acceptable to fill the section of trunking that bridges the cavity with a fire block type expanding foam?

My concerns are de-rating the meter tails and need of if not needed, as client is already upset he can't just move the meter by uncovering incoming main and literately dragging cable + meter and all to new position!!!!!!

 

[1shortcircuit]

Could you run the tails through a piece of plastic pipe that runs through the wall so that the tails do not come into contact with the insulation? :thumbsup

 

[LOYDE]

Not sure I suppose if the pipe was tight, as I've also got to achieve airtightness. Or maybe I could use a intumescent silicone type filler on the pipe ends. Otherwise I might lose points when the SAPs assessment boys turn up and start sucking the air?

 

[malcolmsanford]

In you OP you noted your going to run 50mm steel trunking through the wall 50mm by what ?

Reg 527.2.6 notes that a non fire propagating containment system, which steel trunking is and is below a CSA of 710mm^ then you no need to internally seal the trunking for fire propagation.

After you fit the trunking then you make good the hole that the trunking is going through with the same material as the existing wall.

 

[LOYDE]

Problem sorted, changed box for recessed type so back of meter box now sits tight against the internal skin of cavity.
Have routed cables from cu through 50x50 galv trunking straight through conc bloc into meter box.

Western Power made the connection for us today, all went well except for having to listen to customer lecturing me his thoughts on why non-maintained connections are a waste of money and his opions on why he should be able to mount his cu at a stupid hight and how if we ever want to be rich like him we need to cut corners and ignore what we've learnt all this whilst were a traped audiaence making of all the connections, guys driving me nuts!!

 

[accordfire]

Hi all,

Am new to the forum so hope I've posted correctly.

System 1966 lead TN-S

Am about to move cu to new location, concrete cavity wall with meter box on outside.

Intend to route 25mm tails + 16mm Main bonds through wall via 50mm steel trunking to cu and main earth to met (in meter housing).

Am happy this will comply with additional protection regs but am worried about thermal bridging of the cavity and the potential for a fire to whip up/or through the cavity.

Would it be acceptable to fill the section of trunking that bridges the cavity with a fire block type expanding foam?

My concerns are de-rating the meter tails and need of if not needed, as client is already upset he can't just move the meter by uncovering incoming main and literately dragging cable + meter and all to new position!!!!!!

Providing the "hole" you open up in the wall is re-sealed around your conduit to the same specification as the fire break, there isn't a need to install fire retarding material within the conduit.

However, your conduit - it is part of a continuous system, rather than "just a piece of conduit" stuck in the wall, yes?

If you meant you were using the conduit as a form to ensure the cables don't get compressed only - i.e. open on both sides of the wall, then you must also seal both ends of the conduit.