Alarm Feed

[wreck-it-steve]

Hi,

When installing a house alarm is it a MUST to have it on a fused spur? Can you not just install a 6A MCB to feed it direct and do away with the fused spur?

Thanks

 

[davelx]

Hi,

When installing a house alarm is it a MUST to have it on a fused spur? Can you not just install a 6A MCB to feed it direct and do away with the fused spur?

Thanks

What do the manufacturer's instructions say? If it specifies a fused spur at 3A then that is what you must use to comply with the regs.

ADT insist on a 3A FCU - I've just had that exact discussion with them - and the Honeywell Galaxy installation manual does specify " a means of isolation must be provided within 2 metres of the control panel" (OK, my CU is about 30cm from my panel!) and "a fuse spur with 3A fuse, must be fitted on the live circuit"

So best check the MI's for your panel.

 

[333rocky333]

The fused spur is usually for the engineers to isolate there panel to work on it, there not usually allowed to root around in fuseboxes.
most panels have an internal supply fuse in addition

 

[Taylortwocities]

Usually fit a fused (but not switched) connection unit adjacent to the alarm panel.

 

[JohnW2]

What do the manufacturer's instructions say? If it specifies a fused spur at 3A then that is what you must use to comply with the regs.

Do you think that feeding it with a 3A MCB would be compliant, or do you think that it's necessary to comply with the every word of the MIs?

Kind Regards, John

 

[Robin0577]

Honeywell Galaxy installation manual does specify " a means of isolation must be provided within 2 metres of the control panel"

So best check the MI's for your panel.

I wouldn't have thought an unswitched fused spur counted as a proper means of isolation, given that it breaks the live only?

 

[EFLImpudence]

What do the manufacturer's instructions say? If it specifies a fused spur at 3A then that is what you must use to comply with the regs.

Do you think that feeding it with a 3A MCB would be compliant, or do you think that it's necessary to comply with the every word of the MIs?

I don't know for certain but I would not think the MIs actually call for a 'fused spur' as such.

Wouldn't they just specify the fuse rating and perhaps a means of isolation, possibly stating a double pole and the usual 3mm. separation?

 

[JohnW2]

I wouldn't have thought an unswitched fused spur counted as a proper means of isolation, given that it breaks the live only?

As far as the regs are concerned, one doesn't have to isolate neutral unless it is in a TT installation. Whether you or I (or manufacturers' instructions) regard that as 'proper isolation' is perhaps a different matter.

Kind Regards, John.

 

[JohnW2]

I don't know for certain but I would not think the MIs actually call for a 'fused spur' as such. Wouldn't they just specify the fuse rating and perhaps a means of isolation, possibly stating a double pole and the usual 3mm. separation?

That's what I was also wondering/thinking, and the reason I asked the question.

Kind Regards, John

 

[EFLImpudence]

First one Googled - from Kidde interconnected heat and smoke.

HOW TO INSTALL THIS HEAT ALARM
!DANGER: ELECTRIC SHOCK HAZARD. TURN OFF POWER TO THE HEAT ALARM CIRCUIT AT THE MAIN DISTRIBUTION BOARD BY REMOVING THE FUSE OR SWITCHING THE CIRCUIT BREAKER TO THE OFF POSITION
AND SECURING IT.
!WARNING: THIS HEAT ALARM SHOULD BE INSTALLED ONLY BY A QUALIFIED ELECTRICIAN IN ACCORDANCE WITH THE REGULATIONS FOR ELECTRICAL INSTALLATIONS PUBLISHED BY THE INSTITUTION OF ELECTRICAL ENGINEERS (BS 7671) AND/OR ALL PRESIDING LOCAL, REGIONAL AND NATIONAL CODES.
!WARNING: HEAT ALARMS SHOULD BE CONNECTED ON A SINGLE INDEPENDENT,
DEDICATED CIRCUIT AT THE MAIN DISTRIBUTION BOARD. NO OTHER ELECTRICAL
EQUIPMENT, EXCEPT COMPATIBLE SMOKE AND CO ALARMS, SHOULD BE CONNECTED TO THIS CIRCUIT. IF YOUR HOME HAS RESIDUAL CURRENT DEVICE PROTECTION ON THE ELECTRICAL INSTALLATION OR ON INDIVIDUAL CIRCUITS, CHECK
WITH A QUALIFIED ELECTRICIAN TO MAKE SURE THAT FAULTS ON CIRCUITS SERVING SOCKET OUTLETS OR PORTABLE APPLIANCES CANNOT CAUSE INTERRUPTION
TO THE SUPPLY TO THE HEAT ALARMS.

 

[EFLImpudence]

Presumably if it is not a compulsory fitting to BS5839, i.e. you are just fitting alarms in your own house because you want to, then less stringent methods could be used.

 

[DaftPunk]

Doesn't the EAWR require a spur external to the alarm panel?

Work on or near live conductors
14.  No person shall be engaged in any work activity on or so near any live conductor (other than one suitably covered with insulating material so as to prevent danger) that danger may arise unless–
(a)it is unreasonable in all the circumstances for it to be dead; and
(b)it is reasonable in all the circumstances for him to be at work on or near it while it is live; and
(c)suitable precautions (including where necessary the provision of suitable protective equipment) are taken to prevent injury.

 

[EFLImpudence]

Doesn't the EAWR require a spur external to the alarm panel?

What is it you mean exactly?

A 'spur' is a branch off another circuit.

Do you mean a Fused Connector Unit?

 

[JohnW2]

Doesn't the EAWR require a spur external to the alarm panel?

Like the one that EAWR requires you to have in lighting and sockets circuits of your house? [per EFLI's comment, I assume you mean FCU, not 'spur']

This answer obviously is "of course not"! What both EAWR and common sense require is that there should be some means of removing live electricity from the panel so that it can be installed in the first place and worked on (and also so that it can be switched off if malfunctioning) - but, just as with your lighting and sockets circuits, that could be achieved by, for example, an MCB and/or Main Switch (or equivalent) in the CU.

Kind Regards, John

 

[ericmark]

I spent a year doing nothing else but fitting alarms to BT building and every one had a fuse in the main 48 volt DC distribution board. Clearly it will change installation to installation and manufacturer to manufacturer and there will be no single answer to the question.

However as pointed out most require a point of isolation and isolation requirements vary with the supply type. With a TT supply likely you will require a switched FCU to be able to isolate but with a TN supply a un-switched FCU or single pole MCB would be fine to isolate.

The point is both line and neutral are considered as live conductors.

537.1.2 Combined protective and neutral (PEN) conductors shall not be isolated or switched except as permitted by Regulation 543.3.4.
Except as required by Regulation 537.1.4, in a TN-S or TN-C-S system the neutral conductor need not be isolated or switched where it can be regarded as being reliably connected to Earth by a suitably low impedance. For supplies which are provided in accordance with the Electricity Safety, Quality and Continuity Regulations 2002, the supply neutral conductor (PEN or N) is considered to be connected to Earth by a suitably low impedance.

I would think that most manufacturers do not want to include this in their instructions and it is simpler just to say isolation is required which with a TT system would not be provided by simple removal of the fuse or switching a single pole MCB.

The fuse holder of the standard FCU can take a lock through it locking it off but with the MCB normally some device is required to be able to lock off the MCB. In commercial often the doors to the distribution units can be locked shut as well as using the special clips to attach locks to individual MCBs.

On a personal basis if the supply is TN and there is a clip provided to lock off the MCB then it should comply. With a TT system then a switched FCU would be required with an ability to attach a lock to the switch. Using a keyed double pole switch like used with emergency lights maybe a better way to provide isolation. It could also have a fuse but if fed from a dedicated MCB can't really see the point.

So to recap the main point is what is the supply type. With a TT that's with an earth rod then you need an isolator with a TN that's where the supply company supply the earth then not really required.

Being pedantic if the manufacturer says it needs a switched FCU then you should use one to comply with rules. But with common sense with a TN system not really required.