Prospective fault current

[IQ Electrical]

Ah yes! The guidance notes are very clear! I would also like to point out that in addition to the 50amp limit the consumer unit has to be supplied through a type 2 to bs 1361:1971. very interesting! Now since it's supplied with a bs88 1967 (only a few around) in which western power can not tell me what the k rating is because it so old. I am on them to update it for free to a type ii. So it could comply.

But I do understand that there will be no discrimination in the case such a large current comes through.

So I guess in everyday language what would happen is the mcb/rcbo would break/fuse but the main cut out cut off the supply before any real damage happens according to the annex notes. Correct?

That's the theory!

It'll be interesting to see if the supplier will change the fuse, we find that the mention of an occasional burning smell from the service head area tends to encourage them

 

[Mike Me Mate]

They just got back to me. Its a pretty unclear area for them. They replace the rewirable fuse heads for free. However they seem to want to charge for this one. Technically though they replace the rewirable because I could guaranty a k rating on it cause it didn't say sa1,2,or3. Well in my eyes if they can't give me a rating for this bs88 1967 fuse then? What's the difference?

We then had the discussion of changing the fuse carriages directly over from the bs88 1967 to type 2. He doesn't know but he said if it can then they'll do it for free.

On another note. The rcd. They don't have to have a k rating? Rcd for dual splits don't trip on overload. They work on leakage(earth fault) 30 m/a is 30 m/a. Is there anything to be wary about this?

 

[malcolmsanford]

Yes making sure they trip .....................what do you mean by wary?

 

[Mike Me Mate]

Yeah stupid question sorry. I guess my point is that for a short circuit current the rcd doesnt activate because of there is in theory no imbalance between live and neutral Now if there is an earth fault the PFC will never rise that high because it would cut out at 30ma. So why do they bother putting k ratings on rcd, noticing that they don't put them on mainswitches.

 

[SPARTYKUS]

Yeah stupid question! Sorry!

Hello Mike Me Mate :winkiss:

No such thing in my book (stupid question) although in this industry and with the way it is, you may occasionally get a tongue lashing from someone.... then the thick as a rhino skin needs to play its part.

Even if you are 30 years man and boy there will be something you do not know, or have even, god forbid, perhaps forgotten. It's easy to forget that sometimes though as we are all fickle creatures.

Good luck with the assessment.

 

[tom79bmth]

Hi just a quick note

I have a megger mf1502 and if I leave it in the van over night and its a bit cold my pfc goes very high and ze very low, but fine if I keep in the house must not like the cold had me baffled for for while

 

[Mike Me Mate]

Technical help said that bs88 1967 Should be alright for the 6k board bsen 60439-3
So I guess, that's good enough for me?

Western power said the carriages couldn't be switched.

 

[Engineer54]

Hi just a quick note

I have a megger mf1502 and if I leave it in the van over night and its a bit cold my pfc goes very high and ze very low, but fine if I keep in the house must not like the cold had me baffled for for while

All types of electronic equipment do not like being Cold!! Most test equipment usually stipulates the recommended working environmental parameters in the manual, including the minimum temperature....

 

[Mike Me Mate]

Also like to mention that if the voltage is quite high, say 250 then it can throw off your numbers on your reference charts. v=I(ze) .That can also make you feel like your tester is acting funny.

 

[MarkieSparkie]

Hi just a quick note

I have a megger mf1502 and if I leave it in the van over night and its a bit cold my pfc goes very high and ze very low, but fine if I keep in the house must not like the cold had me baffled for for while

Hi Tom, Megger claim this is due to the batteries that may be used in the early MFT15xx series, the technical department recommend that only Duracell Procell or Duracell standard gold top alkaline cells are used, their tests show increased internal resistance of other cells in cold conditions due to the method of cell construction.