FTTC speeds and impact of distance from the cabinet

I am trying to understand why Broadband speed is so low when i have FTTC enabled and am approx 800-1200 meters from the cabinet. Every thing I read appears to show that with the distance from a FTC enabled cabinet I could get up to 30 Mbps but BT only state aprox 1/2 that figure. I am hoping some one on here can assist with an explanation. Why?
I have a BT broadband boost engineer coming out Monday and I do not want to be in a position of disadvantage by not understanding.
The previous engineer stated that BT only have to gaurantee 50% of the possible speed, does this mena they are limiting speed. i do get 40/10 Mbps coming out of the cabinet, the engineer checked.

Any info realy appreaciated.

Please can you provide the line statistics from your modem?

And the output from putting your telephone number into https://www.dslchecker.bt.com/ be careful not to leave your phone number visible when you paste the results here though.

Do you know the actual cable length between yourself and the cabinets? Cables often travel a tortuous route, not the most obvious, and can double back on themselves. This can sometimes double the length of the cable run. VDSL2 speeds drop off quite rapidly, 30Mbps at around 800m or so dropping to 15/20Mbps at around 1.5Km

Products Downstream Line Rate(Mbps) Upstream Line Rate(Mbps) Availability Date
High Low High Low
FTTC Range A
(Clean) 18.1 11.6 1.3 0.8 -- Available
FTTC Range B
(Impacted) 15 6.4 1.2 0.6 -- Available

WBC ADSL 2+ Up to 3.5 -- 2.5 to 4.5 Available
WBC ADSL 2+
Annex M Up to 3.5 Up to 0.5 2.5 to 4.5 Available
ADSL Max Up to 2.5 -- 1.5 to 5 Available
WBC Fixed Rate 1 -- -- Available
Fixed Rate 1 -- -- Available
Other Offerings
FTTP on Demand 330 30 -- Available
Fibre Multicast -- -- -- Available
Copper Multicast -- -- -- Available

is there any way to actually find the cable length. I have driven as the road goes , which is not as the crow flies and adds quite a bit to the routs and that comes out at .8 miles 1200 meters. Which sits in the range of up to 24 Mbps. But as you say is the run longer???

But as you say is the run longer???

BT clearly think so otherwise they wouldn't be quoting 18.1 - 11.6 for FTTC Range A.

It isn't just about distance. The gauge and material matter too.

The general theory is that you can get around 24Mbps at 1200m of reasonable 0.5mm copper.

If the copper is thinner, you will get lower speeds for the distance. If the copper is thicker, you will get faster speeds.

If the line is made of aluminium, even partially so, then speeds are likely to be lower.

What speed are you getting currently? In terms of sync speed, preferably.

In reply to a post by Spurspat:

is there any way to actually find the cable length...

As another person says there is the actual physical length of the wire, which is one thing. But electrically it may behave a little shorter or longer than that depending on what the wires are made of.

When the boost engineer arrives, they will have a rectangular blue box which a square LCD display on it, it is made by a company called JDSU, you will easily see the JDSU marking on it.

The JDSU can do a number of tests, you will probably find this is the first and only piece of test equipment they use.

The JDSU can do a test which will electrically show how ling the line is, it will also tell you how much attenuation there is on your phone line to the cabinet, ask the engineer and write down both of these numbers

The JDSU also typically, at least in and around the location where I live, connects to ADSL and VDSL at lower speeds than the modem you use.

In reply to a post by godsell4:

The JDSU can do a number of tests, you will probably find this is the first and only piece of test equipment they use.

An Openreach technician could be equipped with a JDSU HST3000c or an Exfo AXS-200/635. How that HHT (hand-held tester) is used depends solely upon the experience of the attending technician.

Does anyone know if FTTP is available again from BT, I understand they had withdrawn the capability. If it is how do you order a survey.