A-1
Appendix A - Surge Protection Risk Assessment
Where a tank gauge probe is installed in a ‘riser’ and the entire probe is within the vapour space of the tank, a risk
assessment is required to assess whether additional surge protection is required in close proximity to the probe.
First, complete the Lightning Risk Assessment by identifying whether the site is suitably described by one of the 6
categories listed. Where required, a lightning ground flash density number can be estimated from the lightning
map on the following page. Tick the box next to the description that best describes the site. If none of the
descriptions apply, then do not tick any box. In this instance, additional surge protection is required in close
proximity to the probe.
Second, step through the overall Surge Risk Assessment. For each statement, tick either True or False. Additional
surge protection is required if any of the statements are False.
Delete as appropriate
Additional surge protection is not required at this site since all entries in the SURGE RISK ASSESSMENT table
above are marked as TRUE.
Additional surge protection is required at this site since one or more entries in the SURGE RISK ASSESSMENT
table above are marked as FALSE
Site name Date Signatory
Download the Risk Assessment Tool at http://www.mygvr.com/
LIGHTNING RISK ASSESSMENT - is the site described by one of the following categories? If yes, tick the relevant box
The site is in a town, village, or built up area
The site is a large motorway site with no probe cable extending more than 5m beyond the area covered by the canopy
The site is a large motorway site with no probe cable extending more than 10m beyond the area covered by the canopy and the
lightning ground flash density is less than 3.38
The site is a large motorway site with no probe cable extending more than 15m beyond the area covered by the canopy and the
lightning ground flash density is less than 2.25
The site is a large motorway site with no probe cable extending more than 20m beyond the area covered by the canopy and the
lightning ground flash density is less than 1.88
The site is in open country with no probe cable extending beyond the area covered by the canopy and the lightning ground flash
density is less than 1.13
SURGE RISK ASSESSMENT True False
A lightning risk assessment has been performed as above and the site falls into one of the categories identified
The installation of the tanks and/or probe is more than 100m away from an electric railway, underground railway, or
tram line
The installation of the tanks and/or probe is more than 100m away from other high voltage sources such as power tur-
bines
The site does not have high voltage power cables supported by pylons passing overhead
The installation does not use above ground tanks
The site is not used for high blend ethanol fuels
The probe cable is buried under the forecourt
The site does NOT use cathodic protection for the tanks
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