Life is is clearly circular. A few months ago I can across in service a 1940s ish steel enclosed MEM "fuse box" and this week when doing a quotation I spotted a 1930s MEM Bakelite one. A long time ago I vaguely recall seeing the iron MEM one that pre dates the Bakelite, and there are images on the web for them. Now that certainly would be fire resistant, except the fumes from hot bakelite could be very nasty.
Anyway, so we will have fire resistant CUs into the future which is all good stuff as statistics must have indicated a fair number of fires were as a consequence of these plastic CU cases. But now I wonder about about the Distributors service heads. On this same job with the Bakelite switch fuse was a 1930s iron clad cutout. I was thinking if the work at this job with the iron cutout goes ahead then I would probably try get the Distributor in to change the cut out for..... a plastic cased one.
Now my inquisitive mind did a quick search on the web and I found that overheating terminals (resistive overheating as the Fire Service call it) on the Distributors cutout is also a common cause of electrical fires. I wonder if we will we see non combustible service heads coming back into fashion.
It has crossed my mind that setting the torque correctly on screw connections might reduce this underlying risk. As an example a few weeks ago I had an intermittent "lighting fault" which was traced to the meter cable connection being loose in the top of the service head cutout. Increased use of torque setting screw drivers would perhaps be good practice. But where do you draw the line for example only on cable sizes 10mm and above, always on main bonding and earthing conductors whatever the size, only on 25mm and above, would different manufactures have different settings for the same screw size etc. I am not asking for answers here, just sharing my thoughts. But I will be thinking about this a little more myself to decide what is my best practice.
Anyway, so we will have fire resistant CUs into the future which is all good stuff as statistics must have indicated a fair number of fires were as a consequence of these plastic CU cases. But now I wonder about about the Distributors service heads. On this same job with the Bakelite switch fuse was a 1930s iron clad cutout. I was thinking if the work at this job with the iron cutout goes ahead then I would probably try get the Distributor in to change the cut out for..... a plastic cased one.
Now my inquisitive mind did a quick search on the web and I found that overheating terminals (resistive overheating as the Fire Service call it) on the Distributors cutout is also a common cause of electrical fires. I wonder if we will we see non combustible service heads coming back into fashion.
It has crossed my mind that setting the torque correctly on screw connections might reduce this underlying risk. As an example a few weeks ago I had an intermittent "lighting fault" which was traced to the meter cable connection being loose in the top of the service head cutout. Increased use of torque setting screw drivers would perhaps be good practice. But where do you draw the line for example only on cable sizes 10mm and above, always on main bonding and earthing conductors whatever the size, only on 25mm and above, would different manufactures have different settings for the same screw size etc. I am not asking for answers here, just sharing my thoughts. But I will be thinking about this a little more myself to decide what is my best practice.
