My cousin is Jewish and Sabbath observant. On Saturdays, he can't do
anything involving electricity, e.g. using a calculator, cd player,
flashlight, telephone etc.

This person had a GEMINI security system installed at his home. The
system beeps when the front door is opened (when disarmed) and shows
"Front Door Open" on its display console. This would not be permitted
for him to do on his Sabbath. So before sundown on Fridays, he enters
a bypass code, which allows him to open his front door without the
beeping or messaging.

The question is: what exactly happens when a bypass code is keyed in?
The system won't beep, but is there no conduction of electricity? Does
the circuit at the front door physically disconnect somehow? If
electricity is still affected by opening the door, (just there's no
audible/visible indication) that would still be a problem for him on
Saturdays.

Note: this is not a religious question. I'm specifically looking for
an answer concerning the mechanics of the alarm system.

Hi schoell-ga,

All Gemini security systems approach the BYPASS function in the same
way. I will be referring to a specific model since you didn't provide
that information and may not know it offhand.

Looking through the owner's manual of the GEM-P400 Security System, we
find the answer to your question:

Firstly, in order to bypass a particular zone, the rest of the system
MUST be armed:

"To bypass a zone, press BYPASS and the zone number to be bypassed,
and then ARM SYSTEM"

http://www.napcosecurity.com/user_manuals/GEM-P400_OI230a_USER.pdf

Since I'm sure the manufacturers of the alarm system do not want to
give out the diagrams explaining exactly how the system operates, some
deductive reasoning and knowledge of electrical circuits is now needed
to answer your question:

1. In order to bypass the any zone, the system must be armed.
Disarming the system will reset all of the bypass commands.
2. The manual also states that by using the bypass function, "the
system will remove the zone from the protected area".
3. Each zone requires some channel to move electrical signals from the
main control unit to each zone.
4. All unprotected areas do not require an electrical current to pass
through them, and therefore engineering design processes would not
provide power to circuit leading to this zone in order to minimize
electricity use. This is one of the design foundations in any
engineering project.
5. Any system approved by a government agency must follow engineering
design principles.

CONCLUSION:

There are two possible scenarios:

1. The main control unit is located in the same zone as the front
door. In this case the circuit will still be active because it needs
to provide signals to other zones which are being protected. Remember
that the bypass function only works when the entire system is set to
ARMED. There is also no discontinuity of the circuit within the zone
itself, therefore electrical current cannot be avoided within the
zone.

2. The main control unit is located in a different zone from the front
door. In this case, the circuit leading from the main control unit to
this zone (which protects the door) has been removed from the "active
circuit". Therefore, there is no electrical current passing through
this area.

There is one minor assumption made here, and that is that any current
remaining in the circuit will pass through the circuit before the
Sabbath restriction comes into effect. Since he does the bypass the
night before, this is a non-issue since electricity moves quite fast
:)

I have tried to answer your question as fully and logically as
possible, since the actual electrical diagrams are privileged
information that the security system company wouldn't want openly
available. I hope for your cousin's sake that his front door is not in
the same zone as the main control unit.

Cheers,

answerguru-ga

I'm happy with your answer, even if it is (as you've indicated) not
100% conclusive, absent manufacturer's diagrams. I believe that Jewish
law treats an action with greater-than-even odds of permissibility as
100% permitted, so in effect your answer is good enough. Thanks!