Re: Mains power cuts and DigitalVoice

andywaring · ‎24-02-2022

Our village recently had power cuts which lasted 48 hours for us but 5 days for others! During that time our landline worked fine. We have no mobile coverage from any provider so we rely heavily on broadband for WiFi calling and our landline.
At almost exactly the same time we got letters from BT encouraging us to switch to digital voice. Will this have any implications for the supply of broadband in the case of a mains power cut? (as long as I have a battery supply for my router)
My concern is that the mains power cut will cut supply to the green box and thus the supply of broadband.

Any insight and advice gratefully received.

jac_95 · ‎24-02-2022

Hi andywaring,

Thanks for the post and welcome to the Community.

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gg30340 · ‎24-02-2022

If you have FTTC broadband all you will need is a battery back up (BBU) to power the BT Hub

If you have FTTP you will need a BBU that can power both the ONT modem and the BT Hub or BBU for each of these devices.

If the power to the "green box" is cut off there is nothing you can do, which is the same as now.

andywaring · ‎24-02-2022

Thank you. Much appreciated.

In the case that the village power is cut due to overhead supply cable damage somewhere, is it inevitable that the supply to the cabinet will be down too? We have an exchange in our village which supplies the cabinets via fibre then copper to the houses. Previously I had thought that the power supply to the exchange was entirely separate from the main grid power supply which is why the telephone still worked in a power cut - am I mistaken?

Keith_Beddoe · ‎24-02-2022

@andywaring wrote:

Previously I had thought that the power supply to the exchange was entirely separate from the main grid power supply which is why the telephone still worked in a power cut - am I mistaken?

As far as I am aware, the line and power from the exchange passed through passive filters in the cabinet and would not be affected by a loss of power in the cabinet. That would not be the case with digital voice.

Power in the exchange is provided by end of rack power units and batteries, and protected by a generator.

gg30340 · ‎24-02-2022

@Keith_Beddoe wrote:

@andywaring wrote:

Previously I had thought that the power supply to the exchange was entirely separate from the main grid power supply which is why the telephone still worked in a power cut - am I mistaken?

As far as I am aware, the line and power from the exchange passed through passive filters in the cabinet and would not be affected by a loss of power in the cabinet. That would not be the case with digital voice.

Power in the exchange is provided by end of rack power units and batteries, and protected by a generator.

What powers the fans in the FTTC cabinet. Is the power supplied from the exchange or from the electricity grid in the street?

I am aware that the exchange has its own BBU/Generator in the event of a power outage hence why the analogue phones still work in a power outage.

jac_95 · ‎24-02-2022

@gg30340 wrote:

@Keith_Beddoe wrote:

@andywaring wrote:

Previously I had thought that the power supply to the exchange was entirely separate from the main grid power supply which is why the telephone still worked in a power cut - am I mistaken?

As far as I am aware, the line and power from the exchange passed through passive filters in the cabinet and would not be affected by a loss of power in the cabinet. That would not be the case with digital voice.

Power in the exchange is provided by end of rack power units and batteries, and protected by a generator.

What powers the fans in the FTTC cabinet. Is the power supplied from the exchange or from the electricity grid in the street?

The FTTC cabs have a battery and power supply from the mains grid that supplies power to the DLSAM, monitoring and cooling systems in the cabinet

licquorice · ‎24-02-2022

Local mains supply

gg30340 · ‎24-02-2022

@jac_95 wrote:

@gg30340 wrote:

@Keith_Beddoe wrote:

@andywaring wrote:

Previously I had thought that the power supply to the exchange was entirely separate from the main grid power supply which is why the telephone still worked in a power cut - am I mistaken?

As far as I am aware, the line and power from the exchange passed through passive filters in the cabinet and would not be affected by a loss of power in the cabinet. That would not be the case with digital voice.

Power in the exchange is provided by end of rack power units and batteries, and protected by a generator.

What powers the fans in the FTTC cabinet. Is the power supplied from the exchange or from the electricity grid in the street?

The FTTC cabs have a battery and power supply from the mains grid that supplies power to the DLSAM, monitoring and cooling systems in the cabinet

Which means when the battery runs out the cabinet stops functioning?

licquorice · ‎24-02-2022

@andywaring wrote:

Previously I had thought that the power supply to the exchange was entirely separate from the main grid power supply which is why the telephone still worked in a power cut - am I mistaken?

The exchange supply is from the same grid source as the rest of the village but has a battery and generator backup. Your landline phone is powered by 50V from the exchange which is why it still works in a power cut.