Question for Zarjaz or anyone

Had an email earlier from Openreach regarding our FTTP build.

What could be the cause of "Light Loss" or similar holding our progress up.

Also what is the procedure for fixing it.

Re-Splice the fibre again. Just guessing.

Hi Mr P******

I have spoken to the delivery manager and she was aware that our contractors had been doing some light loss testing. She has advised that unfortunately these results won’t be accepted as there are still some build issues which will prevent acceptable results at the moment. These build issues are being looked at.

Regards Richard P*****
Infrastructure Solutions Executive Level Complaints Team
Openreach

Edited by busterboy (Sun 02-Aug-20 21:24:25)

In reply to a post by busterboy:

What could be the cause of "Light Loss" or similar holding our progress up.

Bad splices.

Also what is the procedure for fixing it.

Re-Splice the fibre again. Just guessing.

You guessed correctly.

That sort of problem can happen when Zarjaz hasn't done your installation.

Loss in fibre is down to:
- attenuation due to length, but for the total lengths involved with single mode fibre and the total lengths found in FTTP is not *really* a major concern.
- attention due to fibre connectors. Solution is to minimise the total number in a given link. Also APC style connectors are used in PON architectures to minimise the reflections / loss on the return path.
- attenuation due to splitters used in PON architectures. The designers know the limits here during design.
- attenuation due to splices. A good fusion splice is far superior than non-fusion here.
- attenuation due to fibre defects, either during manufacturing or install (crush, kink, too small bend radii etc)

All if the above can be estimated during design and measured following install using a combination of OTDR and light source and power meter.

And don't forget dirt on the connectors.

In reply to a post by candlerb:

And don't forget dirt on the connectors.

Never seen splicing done before but did watch the chap at the end of my drive when he was here.

I noticed he had a bottle of cleaning solution and wipes and did (at least when I watched him) cleaned every joint before using the splicer.

Fingers crossed for a quick fix tomorrow.

Splicer in use pictured here.

In reply to a post by candlerb:

And don't forget dirt on the connectors.

Absolutely. The ferule faces should be inspected (and cleaned) as a matter of routine before commissioning. Whether they actually are or not...

Would be interested to know if the issue is between the handover exchange and your local splitter or between the splitter and your CBT's.

Can add wrong SFP to list of possibilities

In reply to a post by witchunt:

Can add wrong SFP to list of possibilities

I’d put that into the “misconfiguration” bucket, rather than physical “light loss” or attenuation issue, which suggests (to me at least) a physical link issue.

I think many posters are reading the quote in the opening post incorrectly. Including the the OP himself.

It is stated that the light loss tests are being rejected because there are build issues that are being looked into.

That would tie in with the possibility of an incorrect SFP having been fitted, as suggested by witchunt. An SFP being a physical link.

Edited by RobertoS (Mon 03-Aug-20 23:03:22)