Fire Alarm- Earth Fault on Loop (XP95)

[NorthEastSpark]

Hello,
Would welcome any advice-

We have an earth fault to a fire alarm loop, everything connected is XP95 and there are isolators in many bases and call points..

Is there a hints/tips way to find this, without having to gain access everywhere.
Would splitting the loop, powering the half that brings up 'Earth Fault' and disregarding the legs/devices that come up missing work?

I've asked Apollo for any hints/tips but they suggested we buy their test set. Which looks very good, but would hardly be used.

There is no water ingress or other faults at all.
Regards

 

[James]

split loop, using a logical process of elimination, keep splitting the bad part of the loop until you find the fault.

 

[NorthEastSpark]

split loop, using a logical process of elimination, keep splitting the bad part of the loop until you find the fault.

Yup...
The ability to operate the isolators in the bases from the panel would have been handy... but it doesn't exist

 

[UNG]

Break the loop down, isolate (disconnect) each section between the loop isolators until you clear the earth fault then test that section to confirm the earth fault and break that section down until you locate the fault