Do plugs have to be fire rated?

[rewireIT]

Just saw a vid of someone putting in a CU on unistrut in a domestic property (why, i don't know), and one of the comments said it fails the regs because he used regular red rawl plugs instead of fire rated plugs.

I didn't know this was a thing?

 

[loz2754]

It's not a thing, according to Electrical Safety First website q&a section.

 

[rewireIT]

It's not a thing, according to Electrical Safety First website q&a section.

Ah didn't think so. Thanks for the info.

 

[loz2754]

 

[rewireIT]

View attachment 108856

I'd also argue in the vid i saw, that once strut is fixed to the wall it becomes part of 'fabric of the building' and the fixings securing the CU to the strut being metal means it's fire rated.

 

[MJPD29]

No they don’t. By the time a plastic plug melts you’d be in big trouble if you were still in the building.

 

[James]

If i remember correctly the regulation in question is something like,

Cables should be suitably supported to prevent premature collapse in the event of a fire.

It is not applicable to accessories (inc. consumer units) in my opinion, unless they are the sole means of support for the cables or wiring system (never seen it but just in case of confusion)

but when you think about it in a real world scenario, the regulation was put in place after a number of firefighters were found to have died or been trapped by entanglement from cables that had dropped from above into escape routes etc.

It used to be common practice to cable tie (plastic ties) cables to the building structure, other cables, pipes etc. or to mount plastic trunking with multiple cables inside along / across corridors or across doorways.

if there is a fire, most plastics will soften at around 90 Degrees C and have melted or burnt away by 200 Degrees.
leaving a mess of hanging copper to get snared in.

in open air, 100 to 200 deg. is a temperature that will be achieved in a matter of a minute or two in the event of a fire, especially as cables are often run at the top of the room.

Rawl plugs are by design, held inside the brickwork of the building and it will take considerably longer for them to get to a temperature where they are of no structural use so they are not likely to come under the term (premature collapse) as they are held inside a brick that will take quite some time to heat up.

The diference can be demonstrated by holding a blowtorch flame against a plastic cable tie holding something to a metal frame,
then repeat the experiment for the same item being held by a screw into a brick with a plastic plug.
it will take a long time to heat the brick to the point where the screw pulls out of the brick.

In a fierce fire, everything will fail, steel, brick, "fire rated downlights", plasterboard, it will all be destroyed. The key term to remember is "premature"

 

[Intoelectrics]

The diference can be demonstrated by holding a blowtorch flame against a plastic cable tie holding something to a metal frame,
then repeat the experiment for the same item being held by a screw into a brick with a plastic plug.
it will take a long time to heat the brick to the point where the screw pulls out of the brick.

In a fierce fire, everything will fail, steel, brick, "fire rated downlights", plasterboard, it will all be destroyed. The key term to remember is "premature"

Yes, its all about time and exposure. A plastic Rawl plug will fail once the metal screw has heated up enough to soften the plastic plug to an extent where it easily pulls out but in most situations the building is likely to have been vacated by all by the time this happens.
Even so, it might be considered in certain situations where the screws may be subject to high temp exposure whilst the screws are supporting overhead objects. Just thinking about situations where there is a concrete ceiling carrying trunking, tray, etc.. fixed directly under it over exit routes etc. Though not required it might still be worth considering alternative fixing methods if you feel as a designer that it may pose a premature containment failing.