BS 5588 part 5 Section 14 Electrical supplies

[Shaun Doyle]

I was wondering if anyone could throw any light on section 14.1 about electircal supplies for fire fighting lifts / facilties and in particular Note 1.

It states: In the case of some residential buildings where regualar maintenace of a generator would not be expected, the power supplies may be via two seperate intakes into the building from the same external substation and then by two seperate routes to the fire fighting shaft.

"some residential buildings" is a little vague? blocks of flats ok but not hospitals?
What about the size of the building; ok for smaller ones just over 18m etc but what about larger say 36m and above?

Fundalementally, two distinct supplies has always been the way forward as stated in the first paragraph under 14.1.

"regualar maintenace of a generator would not be expected" again a little loose.

With the associated difficulties of fire fighting in high riser buildings, (and fire fighting faciltilies crucial to an successful outcome), why is the standards being whittled down to an extreme that could place fire fighters at even more risk in the light of power intruptions. And if I am reading this correctly, if the substaion is knocked out there is no fire lift?

Grateful on any views and if anyone out there sat on the committee who came up with this gem, I would like to hear from them and where this is pitched at.

[colin todd]

This has always been a bit vague, and the old ''firemen's lifts'' had no secondary supply-scary! It is unlikely that the sub will go at the same time as a fire. I think that is the principle. It really just tries to address the loss of one supply as a result of an incident in the building.

[wee brian]

Its just pointing out that an emergency gennerator on a block of flats will never be serviced so think of something else.

As Colin points out the important bit is the way the power is routed through the building. I've seen supplies from twoe substation coming up the building in the same riser - this is silly.

[kurnal]

Conversely, and in a bid to improve MOE for non ambulant persons in an existing 4 storey building with a single lift and two staircases, as part of a risk assessment I have been trying to persuade the owner to upgrade the lift to 5588 pt8 but the sticking point is the requirement for duplicate power supplies. This cannot be achieved at reasonable cost especially when you look at the automatic changeover and control gear and the need to bring in a seperate feed.
Every other recommendation can easily be met.
But the commentary  in 5588 pt 8 points out that the duplicate supplies are in case a fire IN THE BUILDING causes a power supply failure. The recommendatios then turn this comment into a very prescriptive recommendation.

So is it not possible to provide an equivalent degree of safety by enclosing the power intake in a sterile say 2hr enclosure, taking a seperate tee off the supply side of the company fuse and enclosing the feed to the motor room in a fire resisting duct - say one or two hours FR or use heavy duty micc?

Its a case of so near, so far! and the benefits would be huge for minimal risk in my view.
Of course this is not a firefighting lift!

[wee brian]

I think you put your finger on it there.

The key issue is that the power supply will not be interupted by a fire in the building. This obsession with duplicate supplies has driven us all nuts for years.