Wiring Question: Connecting Elk 150RT + Elk SS15 + Elk SL1 on M1

[dw886]

Hi-

I spent a good part of last evening planning out how to connect the following three items to the M1:

• 150RT Siren (1.2 Amp draw, 6-14 Volts)
• SS15 Siren (550ma, 12 Volts)
• SL1 Strobe (210ma, 12 Volts)

Now after doing the math, and reading the instructions that come with the Elk M1, it sounds like all of the alarm outputs have a combined max of 1 amp. Adding up these three items, in full alarm, I'd be pulling about 2 Amps.

Now to a few questions that maybe someone can help with:

• Knowing what we know about Output 2 (1A max) plus the draw of the Elk 150RT (1.2A), what's the best way to wire this siren?
• For the strobe, I'm assuming that relay on Output 3 is the best option. I have motions/glass breaks installed that have a combined draw of about 400ma in full alarm (by spec, I haven't load tested it yet). Will I have enough power to use the Auxillary power on the M1 to drive the strobe (200ma), and use Output #3 to activate it?
• Assuming that Output 3 is the best option and that there's enough power from the aux power, how do you wire the strobe to pull power and activate through Output 3?

Thanks everyone for all of your help. I can't say enough about how great this site is for learning about all of this - hopefully once this is all done I'll be in a spot where I've learned enough where I can help out others as well.

Thank you!

 

[Del91574]

For the current draw as loaded on the panel, actual loading isn't the important number, it's peak current with everything active....you need to plan on that value and not what the panel is drawing at any particular time.

If you swap out the siren for a speaker, you'll avoid the necessity to add an aux supply. Elk 1RT, same as your siren, just use the onboard driver, then power the strobe from the panel.

Since it looks like you're going to have to go the route of a secondary supply, mainly because your peripherals are going to draw more than you have to supply, I'd recommend either a relay board or Elk 924's (or almost any other TTL relay) connected to the pigtail on the board, then use those to switch the current to the devices as appropriate, programmed in rules.

 

[dw886]

Thanks Del - that's kinda what I was guessing that I'd have to do. When the siding guys trimmed around the 150RT/SL1, they partially covered the plug at the bottom of the siren that covers the allen screw that holds the strobe to the siren. I'm not sure that it's going to be real easy to take the siren/strobe apart for that reason. The can is much more accessible, so I'm thinking that I may just go with the relay that you suggested, and a power supply.

Do you have any recommendations on a power supply for the siren/strobe? I don't plan on powering anything else off of the power supply.

 

[Del91574]

I'd investigate the enclosure further, but barring that...

I'd go with either an Elk or Altronix product, however I would look into sizing appropriately, as many times what you don't believe you need now does come into play as the system grows.

I'd look at 2-2.5A @12VDC as a good starter, in conjunction with a minimum of a 7Ah battery. Once you have that, you could, in theory, shed some load off the M1G as well and improve it's standby times.

 

[tmbrown97]

I've also seen some "cheater" examples from Elk some time ago that mentioned using a relay to activate the siren and having it pull its power straight from the battery bypassing the Elk to get around the total current issue. If it's only one item (like a siren) that seems OK - but if you otherwise will be adding a large load, I'd keep looking towards the additional supply.

 

[Del91574]

Downside of the "cheater" examples would dramatically affect standby time for the main panel. A 1 amp siren draw on a battery is pretty significant, even if it's turned on for 5-10 minutes

 

[dw886]

Hey Del-

I was thinking about this a little more. Do I really need the Elk 924 relay, or can I just use the Form C relay on Output 3 with an additional power supply and an additional battery? Are there any downsides to going that route?

Here's what I'm thinking: I'd keep the SS15 on Output 2, and then put the 150RT and SL1 on Output 3 with a 2.25A power supply and 1280 battery.

 

[Del91574]

You could use Out 3 for the strobe, but if you're going as far as adding another supply, I'd loadshed off the panel with the added benefit of increasing the standby time of the panel with no AC. The relays are under $10 retail to non-trade.

The big item is how the strobe is going to act and timeout, same with the sirens.