Ok let's put this one to bed.
I write this from the point of view of someone who attends somewhere in the region of 5-10 call outs per year to rectify melted shower isolators. I understand the whole 'best practice' and 'industry accepted' arguments, I really do, but from my personal point of view, and from my experience, I have yet to have a problem with a shower that has been directly fed!
The problem is, it is widely accepted, and often required, to fit a readily accessible means of switching off for items of fixed equipment, often found in the form of SFCUs for domestic fitted kitchen appliances, and rotary isolators combined with control equipment for non domestic equipment. SFCUs tend to work well in a kitchen, the connections will never be subject to the amount of heat that the current from an electric shower draws, nor will a domestic cooker for example. The same could be said for devices for switching and isolation in a commercial or industrial environment, and this is because the terminals will be fit for purpose in the sense that you're not provided with just two measly screws to clamp down on to a 10mm conductor. You'll have lugs and bolts. The shower is the only piece of domestic equipment that I can think of that pulls such a significant amount of current, and yet it would seem no one makes a decent means of terminating those cables. Crabtree are close, but it's still just two small screws.
The fact remains, you can spout off regs numbers and ideas about 'best practice' all you like. You may even be right, but when it comes down to personal experience, that being; having nothing but problem after problem after problem with the same piece of equipment, time and time again, is it not right to at least question the validity of the argument that 'fitting a shower isolator is always best'?
Just curious how you would currently comply with 134.1.1 (OK, admittedly, some MI's are better than others!), then, 132.10, 132.15.1 & 132.15.2 if the shower has an inbuilt motor, which obviously depends on the type.
Oh, one last thing, don't yet bank on the proposed changes being set in stone, I was in discussions last week with a few people (IET) and, the amendments were not as yet finalised.
Ok, 134.1.1 not all MIs ask for the isolator (if working to a set that did, that's another argument, see previously attached MIs), 132.10 MCB, 132.15.1 Again, MCB and integral on/off switch,132.15.2 not that any electric shower I've seen has a motor, but if one did, readily accessible switching off is all that is required, not isolation.
It is rare I disagree with you Damien, but this time fella I think you are off your trolley.
Haha, mate, when have you known me not to be off my trolley
Oh could add 537.3 also?
Yes, this states that it does not necessarily need to interrupt the N conductor, however, I'm sure you can find the regulations that make the interrupting of the N conductor a requirement.
So it is not quite so clear cut as to state that a local isolator is not required, at the end of the day a N conductor is still a Live conductor, and, in the event of a fault elsewhere, could pose a lethal hazard to a person undertaking mechanical maintenance on an electrical shower, if, it were not isolated.
The designer of the installation/modification would need to do a robust risk assessment to ensure that this scenario was safe, and be able to prove this in the event of someone being killed, due to them deciding not to fit a double pole shower isolator, especially when it is accepted industry practice to fit one.
Again, MCB. Are you gonna fit DP isolation to every part of a circuit in case it ever needs mechanical maintenance? Does every office need DP isolation for each light fitting for whenever the fluorescent ballasts need changing?
Why have I not fitted 3A fuses for fans fed from normal domestic lighting circuits? Simply because it is a load of nonsense, if fuse protection is required for a puddly little fan then it is going to need to be less than 1A to get near to being the right size.
Why do I install isolators for fixed equipment? So that the equipment can be switched off and/or isolated with relative ease as and when necessary.
Because I was taught to do this by my mentor and see no reason to not do so.
If the DB is in close proximity to the equipment and is only going to need to be isolated by skilled persons then I'm happy with the OCPD or main switch as the isolator.
I know that strictly according to bs7671 this is not required in all situations. But as far as I am concerned bs7671 is at best a minimum standard to work from, never the be all and end all!
Totally agree mate, was just asking out of interest
The only struggle I have, as stated, is the justification for fitting shower isolators.
