My local orthodontist wants me to install 4 extra double sockets in her surgery not a problem i will just create a new ring main it doesnt need special protection as its for non medical gear so i think a 30mA rcd will do. My problem is should i charge her extra as she is the one who charged me loads sorting my teeth out for those that dont know that meant braces etc. regards annemarie
One of the great things about being in business is you can charge as much as you want. The sky's the the limit!! However in a circumstance such as this there is a rule of thumb. Anyone who uses power tools in your mouth and is legally allowed to administer and control pain should be treated extremely fair.
Yes, unless you want to switch dentist (and move all the way across the country) I wouldn't do anything to upset her
Besides, i have the nasty feeling that medical people tend to know each other quite well, so not even that might help.
It's hard to argue in a dentist's surgery, but in most medical rooms I might charge extra for the risk of catching any germs, especially If I had to work around patients (which is admittedly unlikely to happen).
On a more technical note: so you're one of the forums' few defenders of the ring mains? I think most of the Brits here admitted they prefer radials a while ago.
Personally I havn't been able to figure out what the technical advantages of the ring mains could be, compared to two 16 A radials. Granted, voltage drop is slightly lower, but other than that the ring mains actually uses more copper wire than two 16 A radials because the ring has to be completed somewhere. The available power at any given socket is the same, especially since each single socket is limited to 13 A by the plug. All you can save is one MCB.
On the other hand I can understand why the old ways of doing it don't go away easily. For example, if I use conduit I still have a black L1 rather than brown, because that's the way it's been done for the past 40 years and everybody still does it. There's no force to change it either, as both the Austrian and the German regs only state that phases must not be yellow/green, yellow or green. Blue is acceptable if there is no neutral present.
Hi yes i like ring mains especialy when the dist board is pretty full already. the total load will be about 20 amps so it seems a sensible route to take . and yes all noted it mite be best not to upset her otherwise she mite put me in headgear or somthing!
I guess if a 20 A circuit is sufficient for the expected load that seems like the easiest way of doing this. Considering today's copper wire prices I'd really try not to bury any unnecessary wiring.
On a more general note: it's interesting to see how the regional and temporal perception of certain wiring methods differ! For example, some areas of Germany were extremely fond of TN-C systems, i.e. neutral and earth bonded at each socket and light fixture with only two wire (L+PEN) distribution. In fact, electricians there were so convinced of the superiority of their method that they wouldn't use the blue wire even if they happened to install 2w+earth or even 3w+earth cable! They only used black and yellow/green, leaving the blue and brown open. Nowadays, most people frown upon this practice, for a broken PEN is a serious risk of electrocution and 1.5 mm2 or 2.5mm2 wires break much more often than 10 mm2 or larger.
The bottom line is: if you're absolutely used to something, you don't even question it any more, you just accept it.