Daisy chaining ext leads can increase the earth fault loop impedance above that to ensure adequate ADS. Coiled extension leads will generate sufficient heat to melt, due to the Joule heating of the cable as well as the lack of ventilation and other physical issues. Most new extension leads have a coiled & uncoiled rating from the manufacturer. BS7671 states in reg. 510.3 that manufacturers instructions shall be taken account of. It is noted that extension leads do not come under 767,1, however, I'm would guess that ignoring makers guidance would fall foul of MHSWR PUWER98 etc. etc. BTW, I've deliberately used technical terms, as an Engineering Manager should not be asking such things he should KNOW if he is competent to hold his position. If you want further simplification come back to us, I'm sure Zimmy will be along shortly as well as a few others who can back this up.

David I recently carried out a safety inspection in our engineers workshop and found a badly maintained, fully coiled(30m) extension reel. The flex was badly damaged, it had a 2300w heat gun plugged in to it and it was on at the wall(not in use) To cut a long story short, looking at the real which I condemned it stated the max wattage in the fully coiled and un coiled state. It was around 700w. A lot of these newer reels will have information stickers stating this. Not exactly what you were asking, but hope it helps. MAT

I can't type either 'Reel'

Zimmy you're quite correct. I'm glad you are all so understanding on here : -)

Sorry fire but a long extension lead does NOT lead to rcd's taking longer to trip. A long extension lead, as in a long cable length, means that a higher Zs is recorded (ohms) and thus smaller earth fault current, this then means that MCB'S/FUSES take longer to open circuit. Current flow is relatively slow but the effect is almost instantaneous. A bit like putting ball bearings in a glass tube. If the tube is full, as you add one in one end one falls from the other end. Rob