Question Regarding Power Distance

[garethnboyd 0]

So I have a maglock and power supply located maybe 30ft from one another. They function fine, and I'm using a 12v power supply. I have to tie into a fire panel which is about 600-700ft away. Ordinarily I would just splice into the positive wire from the power supply and rout through a normally closed contact at the panel. This distance has me concerned however.

 

Being as I'm not sending both wires that long distance(only the positive), will this situation be an issue? I normally use twisted pair when doing this sort of thing, but I haven't done something at this great a distance from the power supply and lock. Should I use thicker wire?

 

Any advice is appreciated.

[varascope 0]

You should be using 24v with a relay that operates between 6-40 volt range. Here is a connection diagram.

 

[garethnboyd 0]

By auxiliary relay are you talking about my REX devices? Or is this relay something that allows me to overcome the distance issue?

 

 

Sorry if this is an ignorant question.

[varascope 0]

The rating of the relay and voltage drop are both a factor. 24 volts over 18/2 as long as the drop is within the tolerance of the relay, you should have an issue That distance should still have 15 volts. 9 volt drop. On 12v your looking at 3 which should be enough to trigger standard relays.

 

Using 22awg twisted pair on 12v you will not have anything at that distance. On 24vac you will have 3.2v with 22awg.

 

What is the relay model?

[ssmith10pn 0]

Ok, Let me approach this from the code side.

 

First off the fire relay is a supervised device. The code states the fire relay can only have 3 feet of unsupervised wire.

This means the fire alarm people will have to set a relay next to your power supply so that it only has 3 feet of unsupervised wire.

 

Next issue is the fire relay can not have the current flowing through it. It should be dry. This means your power supply will have to have a fire input.

All UL rated access control power supplies have a fire input.

[garethnboyd 0]

Where can I get one of these relays?

[varascope 0]

Do you have a model or schematic of the Access Power supply? I want to check one more item. What is the make and model of the Fire Panel?

[garethnboyd 0]

Well the client just wanted a simple buzz in system with a maglock, so I was just using a 24vdc wall plug. Direct power to the lock with a couple buttons and REX devices(including a timer and PIR sensor) set to simply break the circut when pressed/tripped(all on the positive side). I'm starting to think I may have gone too simple though. Not sure on the fire panel, I know it's an older model. I've been in touch with the company that handles the panel, and they will actually tie in to it. I don't want to touch their stuff because I don't do fire.

[varascope 0]

Do you have a surge rush suppressor on the lock? Using straight to the lock can reduce the life of your system.

 

Once we have the fire panel model we can go through step by step to make sure you are within code.

[garethnboyd 0]

Will do. Thanks for the help. I will let you know that model number as soon as I can get eyes on it.

[garethnboyd 0]

So the panel is a Silent Knight(by Honeywell)

 

There are two boxes, one large one small.

 

Large: SK-5208. PN: 151205 RevB

Small: 5495

 

Sorry it took a few days to get that. I was out of town. I appreciate the help.