Hot Wire Door Holds - MPC-6000

Hello. I have a MPC-6000 and a couple of questions, please, seeking your help. My system has one door hold in place. I am in the process of adding four more. The attached photo shows that one of the panel relays is taking power from the top auxiliary power circuits.

My questions:

  1. How many door holds can be powered by the auxiliary circuit? The devices I’m installing indicate that, at 24V DC, they each draw .015 amps. It seems like 5 door holds will be fine, but I’d appreciate confirmation.

  2. Can I hotwire / hot-add the four new door holds without risk or issue? I’m not worried about 24V DC, per se. I’m just wondering whether there is any risk of shorting the circuit and thereby the main board, possibly doing damage.

  3. Related, perhaps, what is the difference between the top auxiliary circuit (R, -) and the bottom one (+, -)?

Thank you very much for any input.


You should be fine wiring all five of the door holders to one relay using the aux output. The relay is rated at 1 amp and the aux outputs are .4 amps. The top set of aux terminals are resettable meaning when you reset the panel, power drops momentarily. You want to use the bottom aux output as that one is constant.

Thank you, pilot. That’s perfect. Do you also have guidance on whether I may add the new door holds to the system while the wiring is hot?

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Personally I would power the panel off or make sure the wiring isn’t connected to the panel so that you don’t short something out by accident.

Hi, Alex. Good advice, thank you. By way of making sure the wiring is not connected, can I just pull the hot wire from the auxiliary power, then put it back when my door hold wiring work is finished? That won’t cause a short or set off any alerting / alarming, will it? Thanks.

Usually I just cut power to the panel but if you really want to keep the panel on, disconnect the negative wire first then the positive to prevent shorting it out. But just to be safe it’s always a good idea to cut power to the panel.

Okay. Thank you for you guidance.

Hi Alex, others. One further follow-up, if I may. Regarding cutting the power:

  1. I assume I need to both disconnect the batteries and flip the breaker, correct? If so, is there an important sequence to this? Batteries first?

  2. Will cutting the power trigger any alarm?

  3. When reconnecting the power, will the system just simply “reboot” to its appropriate state, or must I do something special?

Thank you.

If you turn the panel off there is no protection while you are connecting the door holds. I’d make sure you inform the customer that the FA panel will be down for X number of hours, etc.

Personally, I’d just remove the 24VDC feeding the door holds so the doors close (failsafe) until you’re done connecting them.

Hi, OFAG. Thank you for the reply. I like your approach. Do I remove the neutral first, from the auxiliary power, then the hot? And then do them in reverse order when adding them back: connect hot first, then neutral? Thanks.

It’s best to disconnect one side of the battery, then turn the circuit breaker off. To power up, turn the breaker on then connect the battery.

Hi, pilot. I appreciate the sequencing specifics. Your approach would seem to completely eliminate any risk of my carelessly causing a short, however unlikely.

May I rightly assume that this approach will not cause any alarms / horns and that, on powering up, the system will simply resume with no loss of configuration / settings / programming?


Yes, the alarms shouldn’t activate if everything is done right and the panel should keep it’s programming stored in the memory card so when it powers up the panel will resume with what it was doing.

Great. I’m on it soon, then. Thank you, all.

All went very well. Thank you for the support, everyone.