School PIR Advice

[jay_t]

Been asked to do a PIR on a school that i've previously done a bit of installation work for. Most of it is fairly straightforward but i have a few concerns regarding sensitive equipment etc..

They have fire detection alarm, intruder alarm, separate alarm for ICT suite and a smoke cloak device.

Anyone know anything about these with regard to how they deal with power going off etc?

I'd probably only test up to the spur that feeds them or maybe even exclude the circuits providing these completely within the limitations but the power will have to go off for all circuits at some point.

Also, i popped in there the other day, i had a couple of hours spare so i thought i'd test a couple of circuits, see what the results were like and give me an idea of how long it would take, how easy access was etc..

Tested a lighting circuit supplying 2 rooms. R1R2 tested fine, pulled the neutral from the block, IR tested L to N (with switches off in the rooms so the fluorescents didn't interfere) tested fine but L to E and N to E both wouldn't test as the meter showed 47v present on the circuit.

Am I overlooking something really basic here?? Any ideas??

Any help much appreciated........

 

[netblindpaul]

Discuss the limitations of the inspection with the customer.

A PIR does NOT require 100% testing of circuits, IIRC GN3 suggests a 10% sample for dismantling & testing.

I don't believe it would be undreasonable to leave some circuits untested due to not being able to isolate etc.

Quite common really, also, unless a private school you may need to check with the LA Building Maintenance section for their requirements.

In my LA area, these guys control the PIR's, and their QS checks them over once done before they get the "Satisfactory" even if they are subbed and no matter what the subbie puts, he has the final say as to whether they are OK'd.

This obviously depends on the subbie doing it propperly, he does have methods for ensuring this too!

 

[M107]

I've just done a quote for a school pir.

Limitations are;

Dead & live testing will be done at a maximum of two accessories per circuit, unless low results are obtained & further sample testing will be undertaken on circuits in question.

The fire detection system to be tested as far as the supplying accessory (fused spur) & same for intruder alarm.

All IR testing will be undertaken with combined line/neutral tested to earth.

Other requests;

That supervised access be granted during non-term time for total power down (no kids on site to worry about then either).

School governing body or head to ensure sensitive equipment (ITC) will be unplugged prior to testing.

 

[jay_t]

Thanks guys

 

[binky]

Fire alarms, and intruder alarm should have battery back-up to keep them working whilst power is off (if they have been maintained properly). Ideally you want someone with alarm code present in case they go off, but generally will allow about 10-20 mins before they start 'beeping' to indicate power supply is off, which is long enough to get test readings up to FCU if you are organised. Re-instating power should shut alarms up, but may need code for Intruder system. I would also check whether systems are remote monitored (BT redcare etc), in which case an authorised person will need to contact call centre to avoid causing panic and school getting charged.

 

[mandark]

Hi just regarding the 47v value found could you be getting a reading from an emergency light pack.