rcd smoke circuit?

[Lee321]

Lostit - you seem to be looking for an argument?Can you back up your claims with some kind of reference material?

Suddenly we have moved the goalposts and you are talking about fire alarm panels rather than smoke alarms.

Discussion is healthy (and the best bit of a forum such as this) but you need to give your side, or state why you disagree with it? Worst case go OT and entertain us. Single line, unreferenced posts are not a lot of help to man nor monkey.

What did you want to get out of this thread?

lol patch this is what a nic guy said thats all was

 

[Lee321]

Since when did the NIC write the regs???I cant believe there is yet another thread on this topic. headbang

they think they did tho ROTFWL

i presumed he was right as i've never seen a fa panel fed by a rcd

i don't even think you can get a mccb rcd/rcbo?

 

[NozSpark]

lol patch this is what a nic guy said thats all was

Out of interest,,,,

without naming names, who told you??

Was it a NIC approved contractor, DI, Assesor, tech help line or someone else????

You do know that if you put 10 electricians in a room that they'll each have a different take on the regs!

 

[NozSpark]

However fire panels should have an independant supply,,, and as they tend to be surface wired and the panel is next to the supply, then you can get away without having RCD protection

 

[Lurch]

At the end of the day, you can supply a fire alarm\smoke alarms with a circuit with no RCD protection if you have the correct cabling and installation methods in place, or you can provide an RCBO\RCD for the specific circuit where it would require an RCD. That's how I've always tended to do it, and I don;t think I've ever fitted any fire alarms or smoke detectors that don;t have mains fail alarms and battery back up anyway.

 

[vandalay]

My take on that is NIC dont want like them RCD protected with other circuits such as on split boards where another circuit on that side of RCD can trip and prefer them on seperate RCBOs, however surely any RCD protection where possible should be our minimum standard.

 

[Lurch]

surely any RCD protection where possible should be our minimum standard.

I take the opposite view, RCD what needs RCDing. I've never been of the way of thinking that we should just RCD everything regardless.

 

[batty]

I take the opposite view, RCD what needs RCDing. I've never been of the way of thinking that we should just RCD everything regardless.

My thoughts too. On rewires I will run smoke detector cables through cupboards if possible and cooker circuits in galv conduit so they don't need RCDing.

Batty

 

[vandalay]

I take the opposite view, RCD what needs RCDing. I've never been of the way of thinking that we should just RCD everything regardless.

Fair enough Lurch, but what situations would you not RCD protect a circuit?

 

[kme]

hmm. so why is the nic saying that a supply to a fire alarm panel should be non rcd regardless?

Direct quote from 5839-1, regarding power supplies:

h) The circuit supplying the fire alarm system should not be protected by a residual current device unless

this is necessary to comply with the requirements of BS 7671. Where a residual current device is

necessary for electrical safety, a fault on any other circuit or equipment in the building should not be

​

capable of resulting in isolation of the supply to the fire alarm system.

Are we satisfied now?

KME

 

[mickey g]

thats the difference between bs5839 pt1 & bs5839 pt6.if lostit had been more specific in his original post much confusion could have been avoided.

i agree with kme and am indeed satisfied ; )

 

[Lurch]

Fair enough Lurch, but what situations would you not RCD protect a circuit?

Under most circumstances, where it didn't need it. That is to say, if BS7671:2008 doesn;t call for RCD protection I generally won;t provide it. It was pretty much the same under the 16th for me.

 

[Stroppy]

What about putting the alarms (domestic smoke/heat) on a frequently-used lighting circuit so that it is RCD protected and obvious if it trips, unlike a seperate RCD circuit that could stay tripped for months without anyone noticing?

 

[Risteard]

RCD protection can only be avoided where it is not otherwise necessary.

If a service shouldn't be RCD protected for whatever reason, then it must be ensured that it is not required for any other reason e.g. unprotected cables buried at a depth of less than 50mm. Presumably this is what the NIC man meant, otherwise he was wrong.

 

[Riggy]

I'm confused as to context here.

The post title talks about smoke alarms, yet the thread then changes to Fire Alarm Panels.

Most of the posts seem to relate to domestic installations (<50mm etc.), but then there are references to trained persons - not allowed as a reason for no RCD in domestics as far as I'm aware. Then we have mention of MCCBs, never seen one yet in domestic installation.

Is it me?

 

[Risteard]

I'm confused as to context here.The post title talks about smoke alarms, yet the thread then changes to Fire Alarm Panels.

Most of the posts seem to relate to domestic installations (<50mm etc.), but then there are references to trained persons - not allowed as a reason for no RCD in domestics as far as I'm aware. Then we have mention of MCCBs, never seen one yet in domestic installation.

Is it me?

Skilled or instructed persons may be the get-out clause here. As you say it mentions smoke alarms but appears to relate to fire detection systems.

 

[Sidewinder]

BTW I've never seen an RCD device that can be added on to an MCCB, nor an MCCB with a built in RCD component. Large current RCD's are available, but lostit's post #22 I am in agreement with, in regard to the availability of large rating RCD's.

However, I don't think you can get an MCCB in a low enough value to adequately protect a cable supplying a typical smoke or fire alarm that would fit into the device terminals. That is less than 10A typically!

So how an MCCB could be fitted directly to a fire alarm supply I don't know.

However, another item for thought. What if there is a requirement for "upstream" RCD's.

KME you seem to have the standards to hand...

However, had enough for today, been busy in front of pc and other things, early night methinks.

All the best all speak tomorrow.

:good night:

 

[SLIPSHOD & SLAPDASH]

Am i missing something here. 6,10,16,20,32 & 40 a Rcbo's are commonly available. The fire Alarm feed is normally wired in 1.5 or 2.5 cable so can be protected by a 16 or 20 A breaker with local fuse to reduce to say 3A

 

[Sidewinder]

Still here, got dragged into something else, YES RBCO's are my post relates to MCCB's, never seen a 6A MCCB!

Going for real now, and NO it was NOT the football!

 

[Riggy]

Am i missing something here. 6,10,16,20,32 & 40 a Rcbo's are commonly available. The fire Alarm feed is normally wired in 1.5 or 2.5 cable so can be protected by a 16 or 20 A breaker with local fuse to reduce to say 3A

Afraid you are missing something (although nothing's very clear in this thread!)

The discussion (I think!) was about MCCB replacements as opposed to MCBs which RCBOs are used in place of.