100mA rcd

[devlin maguire]

Can a 63/100mA S type rcd be used for ring circuits (16th edition install 3 rings rcd protected) failed on the TD setting passed on non time delay??
MAC

 

[Tester Steve]

Eh??

 

[marksparky]

even 16th ed sockets would generally be on a 30ma rcd if they could reasonably be expected to power equipment outdoors eg lawn mower, hedge trimmers, although i stand to be corrected on this. 100ma time delay wud generally be used as a main switch to cover all circuits on a tt installation

 

[devlin maguire]

Hi That was my understanding exactly, but I thought I was missing something. This install I think was put together with what ever was to hand, Things like more than one final circuit in a mcb where spare ways were available, the rcd as described, smokes on light circuits etc.
Mac

 

[Des 56]

I dont quite understand the content of the first post,however the 2nd post has the statement
smokes on light circuits etc.

What may I ask is a better or more highly recomended alternative ?

 

[devlin maguire]

Hi I always reccomend that smoke detectors have a circuit all to themselves where and when required, 314-01-02, 314-01-04, or if you interprete segregation of safety circuits to include smokes 563-01-01, 563-01-04. However Iam open to correction if I am proved wrong
Mac

 

[marksparky]

i too use an individual circuit but there is no problem wiring smoke detectors of a frequently used lighting circuit as long as ther is means of isolation ie double pole switch, domestic smoke alarm supplies are not to be confused with commercial fire alarm which should have its own supply and not on the same rcd supplying other equipment, again i stand to be corrected

 

[Des 56]

I always recomend that smoke alarms in dwellings are not put on a seperate circuit


The on site guide will confirm this page 66
Where the smoke alarm contains a standby battery they are recomended to be taken off a local lighting circuit
Where all circuits are protected by rcd s there is advantage in supplying smoke alarms from regularly used lighting circuits


Segregation of safety circuits and installaing in such a way that they are not interfered with by the failure of other circuits are meant more for fire alarm systems in premises

Domestic smoke alarms do not require such segregation and seperation

The likelyhood of the supply for a dediciated smoke alrm circuit being inadvertantly or deliberately left off is much much greater than if the smokes are taken from a local ;lighting circuit where it is extreemly unlikely that the householder will leave that mcb off

I have yet to hear of a reasonably good argument given for a dedicated circuit for domestic smoke alarms



The 16th edition reg Nos are not relevant

 

[marksparky]

true des but on page 65 osg - b it also says that it should be permanently wired with an independant circuit, its an old argument but none is right or wrong, and if ever wiring on a tt system i put smokes on a 100ma trip of they're own

 

[devlin maguire]

I take your point Des and agree with your reasoning, However I feel that if a smoke alarm is to function to it,s best ability it should not relay on any other circuit that supplies several point of posible failure.
But your point is well made.
Mac

 

[simonspark]

Hello. Aico, the manufacturers, reccomend using lighting circuits. They also state that their detectors be tested using the test switch and not cannister smoke or hot air guns. Also where is the requirement for domestic grade D ( I think) to have DP isolation? Or have I missed something again!

And I cant spell recommend by the looks of it

 

[devlin maguire]

Testing by the button proves very little, I use a lit candle, then blown out the smoke produced should set it off if it does not it should be replaced.
Harsh ? I think not given the alternative
Mac

 

[marksparky]

again p65 osg ther should be means of isolating supply to the alarms without affecting the lighting. i just presume that the only way of safely isolating the supply is by breaking the live and neutral

 

[Tester Steve]

In domestic work, I usually supply smokes from the down stairs lighting circuit via a marked up keyswitch next to the CU. This gives you isolation and when the lights go, someone will notice (hopefully!).

Steve.

 

[simonspark]

One final mention of the smoke alarm stuff to marksparky. Surely the act of unplugging the alarm is a way of isolation from a lightimg circuit. And before you say it would leave live exposed terminals the aico detectors ( no Im not a salesman for them) have little rubberized sleaves so you cant actually touch the terminal,

 

[marksparky]

Isolation-A function intended to cut off for reasons of safety the supply from all, or a discrete section, of the installation by separating the installation or section from every source of electrical energy. p26 brb. so in a word NO removing the smoke head is not adequate means of isolation are u sure ur not an aico salesman u sound lik it to me

 

[simonspark]

It was just a silly idea that appealed to me at the time. I stand corrected.