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Topic Title: .i-switch Fire Rated Switch Disconnector VS fireman switch
Topic Summary:
Created On: 06 October 2016 11:47 AM
Status: Read Only
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 .i-switch Fire Rated Switch Disconnector VS fireman switch   - sarandis10 - 06 October 2016 11:47 AM  
 .i-switch Fire Rated Switch Disconnector VS fireman switch   - sparkingchip - 06 October 2016 12:59 PM  
 .i-switch Fire Rated Switch Disconnector VS fireman switch   - mapj1 - 06 October 2016 01:12 PM  
 .i-switch Fire Rated Switch Disconnector VS fireman switch   - ToniSM - 06 October 2016 02:03 PM  
 .i-switch Fire Rated Switch Disconnector VS fireman switch   - sarandis10 - 06 October 2016 02:10 PM  
 .i-switch Fire Rated Switch Disconnector VS fireman switch   - sparkingchip - 06 October 2016 02:42 PM  
 .i-switch Fire Rated Switch Disconnector VS fireman switch   - sparkingchip - 06 October 2016 02:48 PM  
 .i-switch Fire Rated Switch Disconnector VS fireman switch   - sparkingchip - 06 October 2016 05:37 PM  
 .i-switch Fire Rated Switch Disconnector VS fireman switch   - broadgage - 06 October 2016 06:42 PM  
 .i-switch Fire Rated Switch Disconnector VS fireman switch   - sarandis10 - 07 October 2016 02:35 PM  
 .i-switch Fire Rated Switch Disconnector VS fireman switch   - OMS - 07 October 2016 02:52 PM  
 .i-switch Fire Rated Switch Disconnector VS fireman switch   - di515223 - 07 October 2016 02:48 PM  
 .i-switch Fire Rated Switch Disconnector VS fireman switch   - di515223 - 07 October 2016 02:52 PM  
 .i-switch Fire Rated Switch Disconnector VS fireman switch   - OMS - 07 October 2016 02:57 PM  
 .i-switch Fire Rated Switch Disconnector VS fireman switch   - sparkingchip - 08 October 2016 02:32 PM  
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 06 October 2016 11:47 AM
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sarandis10

Posts: 56
Joined: 21 November 2011

gents what is the difference between a .i-switch Fire Rated Switch Disconnector and a fireman switch. I am working on a crossrail project and we have a switch disconnector and we simply convert it to a firemans switch simply by changing the sticker with the naming on it......is that possible???
 06 October 2016 12:59 PM
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sparkingchip

Posts: 10180
Joined: 18 January 2003

Does the switch go up or down to isolate?

The traditional fire switch has a hole in the end of the lever and goes up to disconnect allowing the use of a pole to easily disconnect the supply when mounted high on a shop front to disconnect the high voltage supply to neon lights etc.

I guess positioning is the relevant issue, along with its intended use.

Andy



 06 October 2016 01:12 PM
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mapj1

Posts: 9690
Joined: 22 July 2004

i-switch is a trade name of Craig & Derricott, who make a full range of switches under this brand, some fire rated (so keep the power on with flames licking around it) some very plastic and clearly not, and also some that are intended as firemans isolators. It may be that they make one that is both, its not very clear.

-------------------------
regards Mike
 06 October 2016 02:03 PM
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ToniSM

Posts: 336
Joined: 21 November 2006

I think the engineering team at cross rail may know the answer to your question. Somehow I doubt swapping labels will come in to their reasoning

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Could there be a better way?

In theory yes, but in practice?
 06 October 2016 02:10 PM
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sarandis10

Posts: 56
Joined: 21 November 2011

agreed swapping labels cant be right. C&G are making fire rated switch disconectors but not firemans switch.

I found on Wiki the following but I was hoping someone to give me a better answer. I spoke with C&D and I wasn't satisfied by their answer

"A fireman's switch is a specialized switch that allows firefighters to quickly disconnect power from high voltage devices that may pose a danger in the event of an emergency.[1] According to the Institution of Electrical Engineers, any electrical device operating at over 1,000 Volts AC or 1,500 volts DC, must be equipped with the switch.[1]

In order to be a valid device, the switch must meet the following standards:[2]
It must isolate all live conductors. Only one switch should control the entire exterior and a second switch control the interior.
The switch should be red and be fitted with a nameplate saying "FIREMAN'S SWITCH".
The ON and OFF positions for the switch must be clearly indicated and visible to someone standing on the ground. Additionally the OFF position must be on the top, this is to help prevent accidental movement to the ON position.
The switch must be in a clearly visible location, not more than 2.75 metres (9 ft 0 in) from the ground. For exterior devices, the switch should be adjacent to the controls for the devices. Interior switches should be adjacent to the main entrance to the building.""
 06 October 2016 02:42 PM
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sparkingchip

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Joined: 18 January 2003

Craig & Derricott has been producing isolating devices for more than 20 years. Combining our switching expertise with the specific requirements of the ventilation industry has led to the development of the 'High Temperature' range of switch disconnectors. Excellent switching characteristics with high temperature environment contact stability makes this the ideal product range.

The critical role performed by these devices is to maintain the power to vital equipment such as ventilation fans, allowing the safe evacuation of a business or public area. Often these devices are mounted local to the extraction fans and, as an assembly, it is essential that they comply with the stringent requirements of BS EN 12101 - 2003.

The complete range are housed in metal enclosures. The user can therefore be assured that there will be no distortion affecting the connecting cables and its supports at high temperatures.

i switch

That isn't the description of a fireman's switch, if mounted high up then it would need someone to go up a ladder rather than being able to use a pole creating safety issues.

Andy
 06 October 2016 02:48 PM
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sparkingchip

Posts: 10180
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The Fireman switch is used for the breaking of the low voltage
circuit of exterior and interior signs and luminaries installations
e.g. neon signs for AC.

The Fireman switch can also be used to operate the under
voltage release or shunt trip in the main incoming breaker. If
there is a fire in the building, the fireman uses an insulated
rod (Firemans axe) to pull the handle to O position which
isolates the utility supply to the building

You cannot do that with a rotary isolator.


ABB

Andy


.
 06 October 2016 05:37 PM
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sparkingchip

Posts: 10180
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Originally posted by: sarandis10

gents what is the difference between a .i-switch Fire Rated Switch Disconnector and a fireman switch. I am working on a crossrail project and we have a switch disconnector and we simply convert it to a firemans switch simply by changing the sticker with the naming on it......is that possible???



I have decided the answer is the i-switch is designed to keep things running if there is a fire and the fireman's switch is designed to isolate things if there is a fire.

So two completely different purposes, though they are both red.

So what use are they being put to?

Andy
 06 October 2016 06:42 PM
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broadgage

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To summarise, a fireman's switch is intended for operation by fireman to isolate the supply to high voltage or otherwise hazardous equipment in order to facilitate safer firefighting.
Common applications are for petrol pumps and high voltage neon signs.

A fire rated switch is intended for the isolation of equipment under normal conditions, to facilitate safe repair or maintenance, and is ALSO designed to resist fire up to certain limits of time and temperature, in order to keep vital equipment working in a fire.
Common applications are smoke extract fans, electric fire pumps, and fire fighting lifts.
Note that a fire rated switch is not intended to survive undamaged, it will need replacing after the fire, but it should survive to the extent of not interrupting the supply.

It might be possible to manufacture a product that fulfils BOTH requirements, and could be used as either a fireman's switch or as a fire rated switch, though I am not aware of any such product.
 07 October 2016 02:35 PM
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sarandis10

Posts: 56
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they want to switch off the pressurisation system.

Is it safe to say that the firemans switch kills the whole power of the building and the Switch Disconnector disconnects just the fans?
 07 October 2016 02:52 PM
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OMS

Posts: 22428
Joined: 23 March 2004

Originally posted by: sarandis10

they want to switch off the pressurisation system.

Is it safe to say that the firemans switch kills the whole power of the building and the Switch Disconnector disconnects just the fans?


No it's not safe to say that - you need to know what the fire strategy is

If this is a pressurization system for smoke (ie the fans keep a certain area or fire fighting shaft clear of smoke by pressurizing it to limit smoke ingress) then it s a fire fighting decision to turn them off - for that, you usually need a fire rated isolator that is accessible to the FRS - that may be at the safety source changeover position within the fire fighting shaft

If the intent is kill off the building power, how do the fans keep working ?

And a note about terminology - the fireman's switch is actually the fire-fighters switch - it has a very specific purpose as Broadgage highlighted above - if you don't have internal or external HV systems, then you probably don't need one

You clearly do need isolators to maintain circuit integrity and that may be used by FRS

What exactly are you trying to achieve ?

Regards

OMS

-------------------------
Let the wind blow you, across a big floor.
 07 October 2016 02:48 PM
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di515223

Posts: 337
Joined: 08 July 2010

That's an oversimplification - The pressurisation system may require to continue to operate whilst there is a local fire in the area of the switchgear, which would force the use of a fire rated switch.
The absolute requirement will be specified by the specific usage. Don't assume, confirm what is required.

Dave
 07 October 2016 02:52 PM
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di515223

Posts: 337
Joined: 08 July 2010

One other question - What rating is required - that will give some sort of as clue - if it is more than a few amps, it is not likely to be a fireman's switch.

Dave
 07 October 2016 02:57 PM
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OMS

Posts: 22428
Joined: 23 March 2004

This is likely to be a switch that allows FRS to depressurize a station after escape has taken place to allow venting of smoke from below ground or to avoid forcing smoke along the tracks to another station - the Crossrail team and FRS will have some very specific requirements on this issue (or they most certainly did last time I was involved with it)

Regards

OMS

-------------------------
Let the wind blow you, across a big floor.
 08 October 2016 02:32 PM
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sparkingchip

Posts: 10180
Joined: 18 January 2003

I went into a wholesaler I don't generally use this morning and they have an iswitch on the wall, it is a good quality die cast aluminium isolator, not a firefighters switch.

So it's down to usage and the fan supply sounds like the correct usage.

Andy
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