Query replacing Openreach BBU on FTTP ONT with UPS

[miketheboat]

I work from home and, having read various Forum entries, I am replacing the existing Openreach supplied BBU with the relevant Cyberpower 24W UPS from the BT Shop to maintain both landlines (2 in my case) and broadband for much longer than the BBU achieves. 

My problem is that, in addition to the power connection, there is a second line between BBU and ONT which I don’t understand the purpose of (arrowed on the unit image) and, where it lands on the ONT, there is a warning label (see label image). 

Second link cable endsWarning label

Would I be right in thinking the label warning applies to the ONT itself and not the connection so I can remove the connection without worry?

Any advice greatly appreciated.

[Les-Gibson]

Yes you can safely remove the BBU and the BBU cable. I did it myself sometime back and have had no issues

[miketheboat]

Many thanks. That all seems to be working a treat.  I'll give it 24 hours to charge up and then test it with power off.

Just out of interest, do we know what the additional connection between BBU and ONT was for?

[Les-Gibson]

No afraid not.

I've got an unproven theory that it's for power monitoring whereby the batteries in the BBU take over in the event of a power fail.

[miketheboat · Accepted solution]

I'll live on in ignorance. Thanks anyway.

[-Richie-]

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@miketheboatwrote:

Just out of interest, do we know what the additional connection between BBU and ONT was for?

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I'm 99% sure it was for when FVA (Fibre Voice Access) was to be a thing for voice calls, Ofcom made it a requirement in the early days, the requirements then changed so it's no longer part of the newer models used.

[miketheboat]

Thank you for that. My original installation was 2016. An image on another community from 2018 did not have the extra connection which is what caught me out.
Onward and upward.