Hi - I am preparing for my NICEIC DI assessment and have a question regarding the filling out of domestic installers' electrical installation certificates. Ideally, I am looking for an answer from those sparks who already use these forms (eg form DCM2).
Under 'Supply Characteristics', nominal current rating of primary supply overcurrent protective device is simply the value of the supplier's cut-out fuse. No problem there.
Under 'Particulars of Installation at the Origin, Maximum demand (load)' I understand that this is the consumer unit total load with diversity taken into account (I also understand that there is more than one way to apply diversity, according to Appendix 1 of OSG).
However, in the real world, this second quantity might easily be higher than the first, with no detrimental effect on the running of the installation. For instance, you could have a 60A main cut-out, yet have a maximum demand of over 100A (1 x 32A ring final, 1x20A radial final, 1x16A immersion, 1x40A shower, 2x6A lighting). This maximum demand would, in reality, never reach that figure: testing above installation with everything running full-tilt, I measured 73A being drawn at the origin, using a clamp meter. I believe the 60A HBC fuse can easily take this load, especially for short durations).
Ideally, the suppliers' cut-out would be upgraded, at least to 80A, but this may not be easily achieved, dependent on rating of incoming supply cable, cost, etc.
So, back to my question to self-certifying sparks out there: is it acceptable for the figures for maximum demand to exceed the rating of the supply cut-out when filling in the EIC?
Many thanks - great forum, by the way guys!
Under 'Supply Characteristics', nominal current rating of primary supply overcurrent protective device is simply the value of the supplier's cut-out fuse. No problem there.
Under 'Particulars of Installation at the Origin, Maximum demand (load)' I understand that this is the consumer unit total load with diversity taken into account (I also understand that there is more than one way to apply diversity, according to Appendix 1 of OSG).
However, in the real world, this second quantity might easily be higher than the first, with no detrimental effect on the running of the installation. For instance, you could have a 60A main cut-out, yet have a maximum demand of over 100A (1 x 32A ring final, 1x20A radial final, 1x16A immersion, 1x40A shower, 2x6A lighting). This maximum demand would, in reality, never reach that figure: testing above installation with everything running full-tilt, I measured 73A being drawn at the origin, using a clamp meter. I believe the 60A HBC fuse can easily take this load, especially for short durations).
Ideally, the suppliers' cut-out would be upgraded, at least to 80A, but this may not be easily achieved, dependent on rating of incoming supply cable, cost, etc.
So, back to my question to self-certifying sparks out there: is it acceptable for the figures for maximum demand to exceed the rating of the supply cut-out when filling in the EIC?
Many thanks - great forum, by the way guys!
