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100 amp timer
Resource: safe electric wiring
2023
John says:
Found your site and want to make sure I understand what options I have for controlling 100A 240V AC on a timer.
It looks like the T30000R series will run what I want?
Image of project

Gene says:

The Intermatic T30000R series control panel will NOT  work ... it is rated 100 amp ... BUT it cannot switch 100 amp.
The T30000R is rated 100 amp only because the busbar can support up to 100 amps worth of circuit breakers.
The T104, T101, T106 timers that come with T30000R series are rated 40 amp (5 HP @ 240V), with max wire size of 8 gauge.

There is no timer that I am aware that will switch 100 amp.

Solution 1
The only way a timer can control 100 amps AC is using 100 amp contactor ... like shown on amazon https://amzn.to/3pgXJpk
... these contactors mount on a din rail or screwed into an enclosure, and are large, 5"x5" etc. Check specs before buying..

Your timer can be any model, mechanical or electronic, or use wifi, zwave, dawn-dusk.
Ordinary wall timer will work and is good choice because it mounts in a simple wall box

For example, you would buy 100 amp contactor with 120 volt coil
Be careful the coil voltage is specified, and check specs shown on box when it arrives
The timer turns on the contactor coil ... and the contactor switches 100 amp circuit.

You will need an enclosure to fit the contactor ... so note the contactor dimensions ... like 5" x 5" etc and consider something like the Cantex PVC enclosures (see pdf) for example Amazon product B000V4LHTS ... or search for Bud Industries box.
You need a tapered drill bit to make holes in PVC box for conduit ... drill 3/4" for 1/2" KO and 1" for 3/4" KO

Solution 2 is to manually switch the circuits using 100 amp safety switches... with the hand lever mounted on side of enclosure.

John says:
Thank you! This has been extremely helpful!!!


Caution
-Switching your grid power off each day will cause power outage, and surge ... and may effect electronics and household clock settings
-Many digital timers will lose their programmng with power outage. Exception, hardwired dial timers such Intermatic KM Series, or E1020 , , and some timer modules like FM1 are not affected.
A photoeye might not function correctly with temporary outage.

Gene says:
General illustration of project .., except your contactor is much larger and wires are 1/0, and breaker etc must match amp rating of load.
Note: suggested timer can be ordinary wall timer, or photoeye or dawn-dusk timer, wifi etc that is connected directly to 120 volt.
The enclosure (Box) must be large enough for the contactor plus space for 1/0 wires ... and 1/0 wires are large and hard to bend.


Coil voltage:
Contactors have various coil voltages. ... 24v 120-208v. 240v 277v etc
The coil voltage is what causes the contactor to activate and turn on load.
Its VERY important to match coil voltage to timer voltage... When shopping, dont get sidetracked looking at voltage rating of contactor, since most are rated up to 240 v minimum... often the sellers show contactor voltage and avoid showing coil voltage since they might not know, because they just sell stuff.

Larger image
Resources:
How to wire Zwave contactor
Project step-by-step
Override air conditioner with timer


John says:
Here's a drawing of proposed wiring for Migro contactor.

Gene says:
Your drawing shows the 4-pole Migro contact, switching both Hot wires and the Neutral.
Typically, in ordinary residential wiring, a Neutral wire is NOT switched, but I do not know the codes for solar.

The real problem with this project is 100 amp   ... 50-60 amp are typical range for ordinary residential and commercial mass-produced products.
100+ amp switching is not common, and starts to edge into industrial switchgear, which is trade-specialized and not found among internet results.

Using Amazon ASIN numbers to identify products:
ASIN numbers are searchable on Amazon and appear on each amazon link and on each amazon page

Read the contactor specifications:
You're looking at  Migro  4-pole contactor B07CHVPSKJ with normally open contacts, size  7.7 x 4.3 x 3.3 inches
The fine print says ... Resistive load 80 A ... not 100 amp, so you don't want to switch under full load.

General purpose rating for the Migro is only 60 A. Ballast 60 A. Tungsten  60 A
90 VA Inrush  ... VA means volt-amp or watts ... means contactor consumes 90 watts to activate contactor.

Coil voltage is shown as 110-120v which might imply they are bending to layman's understanding of electricity (standard voltages in US are 120-240 NOT 110-220)... 110V-220V are listed as minimum acceptable voltages the power company delivers to homes.
Undervoltage or low voltage on a coil can cause contactor to 'chatter' on-off, causing unreliable power and burn out non-protected motors etc.

If the Migro contactor is just 80 amp, and you're worried, then consider the B088848GBS   90 amp definite purpose contactor, which is probably a better choice for numerous reasons, such as better screws, but contactor might be noisy.

Your choice of timer is a plug-in bar timer B0C15BBTDC ... not good choice ... it's a lamp timer, and not even grounded.

Look at timers on following page: http://waterheatertimer.org/Programmable.html#honeywell and consider buying the Honeywell, which is my recommendation.
Timers that do not need Neutral wire are usually NOT rated for inductive loads like a contactor, but it's only 90 watt.

More wiring illustrations on following link
http://waterheatertimer.org/Connectwires.html

John says:
Here's a drawing of proposed wiring for project.

Gene says:
Your drawing shows the timers only receiving power at certain times of day.
Usually timer must receive power full time to function as expected.

Be careful using 1/0 aluminum wire (AL) with contactors etc that are rated CU or Clad ... you need devices rated CU/AL.


Cautions
Many digital timers will lose their programmng with power outage.
Switching your power source each day will cause power outage, and surge
Note: the dial type timer will not lose programming with temporary flicker of power.
Caution
-Switching your grid power off each day will cause power outage, and surge ... and may effect electronics and household clock settings
Caution
-If you are going to turn off all grid power to home for a moment...to connect solar power...
Then the circuit supplying power to timer and contactor will turn off, so contactor will momentarily turn on.
The contactor will disconnect grid power, but then turn off and restore grid power, and then disconnect... and basically chatter on-off indefinitely.

This means the power to the timer and contactor must be continuous 120V from grid.




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