ESB supply night storage capacity

funcrusher

I'm trying to figure out the circuit protection on a newly connected installation. 16kVA supply with a 100A fuse, linked to an incoming 24hr meter and also a dedicated Night Storage tariff circuit. NS controlled by a separate ISKRA meter type 07MID003 and an ISKRA contactor NSH100. Both these devices are marked 100Amp rated. Both incoming circuits feed through customer disconnect switches to respective consumer units All standard stuff....

BUT is there any circuit protection within the contactor to limit the NS load? As NS involves huge constant loads, what prevents the combined night-time load of both circuits exceeding the 100A ESB fuse? Some ESB literature makes a casual reference to a limit of 12kVA on NS supply, but I see no sign of any circuit protection - so maybe that is merely guidance to installers.

I imagine that ESB use design precautions which assume their fuse may not fail below say 120A, and that their supply cable must be designed to safely carry in excess of 120A. But we don't want to blow the ESB fuse.....

I can easily design and install more protection if necessary - but is it already built-in into the ESB apparatus?

Solair

Have you tried the Electrical forum : http://www.boards.ie/vbulletin/forumdisplay.php?f=1018