KA RATING

[frankie310581]

Just thinking today and not 100% sure on the following:

If you have a 3phase supply, supplying a section board that is feeding several dbs throughout a building some of which are 3phase, some single phase and your ka at the supply end is 4.2ka l-n so l-l is 8.4ka so 10000ka rated to be used. Do the single phase dbs in the building have to be 10000 or can they be rated to that individual db ka rating? I hope the expelation is clear

 

[Andy™]

they can be to the max PFC they would be expected to handle. so PFC at that board

 

[frankie310581]

Cheers andy what got me thinking was the caretaker hoovering and it was pluged in to a classroom and off he went down the hall in to the it room which is fed off its own db so there is a possibility of 400v so pfc would be 8.4 or is this something out of our control

 

[Andy™]

if caretaker plugs hoover into a socket in one room, then rams the other end of the cable into a socket in another room, then Darwin springs to mind....

 

[frankie310581]

Lol it was just the way he was hoovering under the desks and moving the computer leads with the vac can you picture it they are not the brightest

 

[Andy™]

for a live part inside the hoover to come into contact with a live part inside another appliance is almost impossible

more chance of winning the lottery, even if you dont play it

 

[frankie310581]

Constructive replay I see lol don't see how the post implies that I play with 3 phase at all I thought this was a forum for electricians to have discussions on things we come across some ppl

Very true Andy it just pop in to my head as I seen it sad sum mite say

 

[kme]

Oh, dear.

I really believe this is a serious state of affairs. It should never have been allowed to degrade to the current state of ineptitude.

Nurse? More medication, if you would be so kind!

(If I can do it, it must be able to be done?..... :coat )

 

[M107]

You asked the question Andy answered it but now you move the goal posts to include a near on impossible senario, just the sort of thing that lead to the pain in the backside risk assessment culture we have today.

 

[Robin Spark]

In this situation, then perhaps more sensible options would be to look at how the computer cables are arranged and find a way to contain them and tidy them up so as they are not moved about on a daily basis.

 

[Bingo]

The easiest solution is to get 10ka rated mcbs throghout if you was worried about the impossible happening.

But i would just go by the ka rating at the local db which if single phase will be lower than the 4.2 at the origin(6ka).Of course the 3 phase dbs will be lower than the 8.4 at the origin aswell.

Hope this helps.

Bingo

 

[Voltimax]

Don't ask these clowns, come to the master...........oh....sorry................ I misread the thread title, I thought it was KARATEING. My bad, soz

:coat