Main isolator 60 amp BS3036 are they still OK to use?

[Pip]

Hi Guys,

Have been doing a Condition report on a social club, and the system is a TN-S. There is a MEM BS3036 isolator after the main fuse which seems to have been there a while. It says 60 amp on the casing, I can't confirm the fuse wire is 60 amp, but it's there.

This isolator is in the meter cupboard which is a adjoining property owned by the club, but is locked after 5 pm so no access, but that's another issue.

There is a 20 meter run of concentric cable(?) (25mm single core surrounded by 30ish insulated single wires used as the neutral, and 6 un-insulated wires used as the earth) from meter cupboard to the CU where it is split to run a 2nd CU another 10 meters or so way (this 2nd CU in turn feeds a 3rd CU from an MCB in it)

Question is, is this isolator still ok to use or should I recommend they change it?
And Is the cable also fit for purpose?

I am having a problem with the RCD on the 2nd board tripping when doing my No Trip PFC tests, and also Tripping at below 1/2In on the RCD test, any thoughts on this one?

Sorry if this is a bit long winded

Thanks P

 

[telectrix]

isolator and cable should be fit for continued use. as long as fuse rating is suitable for the cable it supplies. as for the rCD try a ramp test and also check for eath leakage with a clamp meter. it may be that the installation has some leakage and your tester is taking it past it's threshold.

 

[Pip]

Hi Tel,
Have tried a Ramp test and it still trips,

I have had this same thing happen at a house a few weeks back when fitting power to a sewerage pump system, did not get into finding the reason why in that situation, made a note on the minor works etc..

Will do the same here and advise further investigation

Thank for the info on the 3036 and cable, I'll leave that well alone.

 

[Plonker 3]

Did you do the ramp test with all loads disconnected?

At what am reading did it trip at?

 

[Pip]

Hi Dillb,

I only managed to get one reading out of various times I tested the RCD on a Ramp test, and have forgotten what it was right now. All it would do is show TRIP on my Meter.

I tested the RCD alone with all breakers off, now without disconnecting all the circuits from the consumer unit Im not sure how best to go about disconnecting all the loads.

I have read on this forum a possible issue with Megger 1552 MFT and RCD tripping, The RCD is a Clipsal by the way, could this be a cause?

Also batteries in he MFT getting low?

 

[Plonker 3]

To isolate all loads, turn the main switch off and prove the outgoing side is dead, then disconnect the busbar and neutral from the outgoing side. Or as you have done, although there could be a imbalance between the earths and neutral which may cause false readings.

Then carry do a ramp test and record what current it trips at. You need the ma value to determine if the RCD is faulty or not.

 

[Pip]

Yes, the could be an imbalance on the earth and neutral side, as with all breakers off, that is the live side isolated, but I did not remove the neutral link to the busbar, that will have to be a job for the new year, as this is job was a EICR I have noted the issue and advised further investigation.
It did cross my mind to swap it out for another RCD just to see what the result maybe, but time did not allow
Thanks for your input

 

[Engineer54]

There is a 20 meter run of concentric cable(?) (25mm single core surrounded by 30ish insulated single wires used as the neutral, and 6 un-insulated wires used as the earth) from meter cupboard to the CU where it is split to run a 2nd CU another 10 meters or so way

The cable is called a ''Split Concentric'' and it won't have 30ish (or anywhere near) insulated neutral conductors. And yes it is fit for purpose, if sized and installed correctly. Though most of these cables that i've seen installed, the tail dressing terminations have all been a real pigs ear of a job...

 

[Pip]

Engineer, Thanks for the correction.
I can't comment on the dressing at the meter end where it comes out of the 60amp Fused isolator, but when I first came in to inspect the premises, and the consumer unit had not only the split concentric cable in the main breaker but also a second set of tails running to the 2nd consumer unit, and the live tails loose in the breaker I knew I was in for an interesting day.

 

[Deleted member 72666]

[h=2]Main isolator 60 amp BS3036 are they still OK to use?[/h]What's the pssc/pefc as that will determine if it's still okay to use?

 

[malcolmsanford]

I know your not on Pip but if you do come back on there could be a good chance that the MEM Switch Fuse, never yet seen an isolator with a fuse in it, could have asbestos flash guards in the carrier, so be very careful if you do get access to it