BS3036 breaking capacity and PFC..

[Deleted member 26818]

It's not an indication of whether the devices will break a circuit.
It's an indication of the current that can be broken without damage to the equipment.

 

[Lucien Nunes]

My comment was just an aside that use of Wylex boards on supplies of typical PFC does not often seem to result in electrical apocalypse when a fault occurs. Nor do I recall seeing one that was destroyed by the fault current making it unfit for re-use.

In the case of an MCB the difference between Ics and Icu is not necessarily obvious to the user as the damage sustained is hidden inside, so you need to know from the figures that it won't be overstressed and remain in service in a damaged condition. At least with a BS3036 you can see if it is in a damaged condition because it will be in pieces!

 

[Deleted member 26818]

What I have never quite understood, is why a 3, 6 or even 10 kA device can be rated at 16kA when lumped together whith other devices in an enclosure, yet it is rated at the stated kA when installed singularly in a panel?

 

[happysteve]

What I have never quite understood, is why a 3, 6 or even 10 kA device can be rated at 16kA when lumped together whith other devices in an enclosure, yet it is rated at the stated kA when installed singularly in a panel?

It's because they give each other moral support. There's no I[SUB]cn[/SUB] in team.

 

[trev]

There's no I in team.

You know the stock answer to that hough don't you?

 

[happysteve]

I reckon I might know a word with a U in it, if that's what you're on about?

 

[Deleted member 26818]

Only the one word?

 

[happysteve]

Only the one word?

Sorry, yes. "Douchebag" is the only one I can think of. Perhaps as I get more experience on site I'll learn some others...?

Is this the sort of thing that's assessed on AM2?

 

[Risteard]

Annex ZA is a UK-only derogation. This gives the conditional rating (N.B. it is CONDITIONAL on, as spinlondon says, it being in a type-tested assembly etc.). I'm not sure why you would be uncomfortable with it - if the assembly meets the requirements for the conditional rating along with the upstream protection then it is entirely safe.

 

[Deleted member 26818]

Not a question of comfort, more a lack of understanding.
A device rated at 3kA is rated at 16kA when lumped together with other devices in an enclosure with quite limited space, whereas when placed in a panel with perhaps one or two other devices (sometimes none), with lots of space around, it is only rated at 3kA.

 

[HappyHippyDad]

Well... I contacted the Wylex helpline (01543 455000 - just in case anyone else wants it) and ALL wylex rewireable fuse holders are rated at 2kA.

The chap stated that the only one rated at 1kW was the 5A plug in MCB (with the 2 round push buttons on it).

He also stated that he is not aware of any rated at 4kW which was strange as they are clearly mentioned on some of the data sheets.

 

[Lucien Nunes]

Thanks for confirming this - I have also understood the breaking capacity to be 2kA and used that figure in the past, although not having an authoritative source I didn't mention it. The low Ics of the old Stotz pushbutton MCBs was par for the course in their day, which was a long time ago. I have a 5A example here and it is indeed rated M1.