I've Replaced 14 Reversing Contactors in 2 Years (Here's My Pre-Order Checklist)
Who This Is For (And Why You'll Want This)
If you're ordering abb-contactor components—specifically reversing contactors or DP contactor 40 A units—and you've ever received the wrong part, I've been there. This checklist is for electrical engineers, panel builders, and maintenance leads who are tired of reordering because of dumb, avoidable mistakes.
It's not about theory. It's a step-by-step process I now use before every order. It took me 3 years and about 150 orders to understand that skipping even one step can cost you a week of downtime.
The 5-Step Pre-Order Checklist
Step 1: Confirm the Contactor Type, Not Just the Part Number
You'd think this is obvious. It's not. I've ordered an abb reversing contactor when I needed a standard DP contactor 40 A more times than I want to admit. The part numbers look similar, and if you're rushing, you'll grab the wrong one.
Here's what I do now: I pull up the datasheet and physically check the coil voltage and contact configuration. Not the catalog page—the datasheet. I've caught three mismatches this year alone because the catalog listed a "reversing" variant that actually wasn't.
I knew I should check the datasheet, but thought 'what are the odds?' Well, the odds caught up with me when I ordered six reversing contactors for a non-reversing application. $890 in redo plus a 1-week delay.
So now my rule is: datasheet before cart.
Step 2: Map Your Control Circuit Voltage (This Is Where It Gets Weird)
This is the step most people skip. You're looking at the contactor's main contacts and assuming the coil voltage matches your control circuit. It doesn't always. A DP contactor 40 A might have a 24V AC coil, but your panel runs on 110V AC. I've seen an entire batch of contactors fail because of this mismatch.
The hidden cost is not just the part—it's the time spent diagnosing why the contactor won't pull in. I remember one job where the electrician spent four hours tracing wires before realizing the coil voltage was wrong. That's $400 in labor for something a simple check would have caught.
So glad I now make it a rule to verify coil voltage on every order. Almost skipped it on a $3,200 order of abb reversing contactors, which would have meant complete rework.
Step 3: Verify the Enclosure Rating (Don't Assume 'Indoor' Means 'Dry')
Another gotcha: the enclosure rating on your abb-contactor. I once ordered standard IP20-rated contactors for a panel in a washdown area. They lasted three months before corrosion killed them. The replacement cost wasn't just the parts—it was the production downtime.
Check if you need IP54, IP65, or something else. And don't assume that because the panel is indoors, it's dry. Condensation, cleaning chemicals, and even high humidity can cause issues.
Industry standard for washdown areas is IP65 minimum. I now include this in my checklist because I learned the hard way.
Step 4: Cross-Check Accessories (Thermal Overloads, Auxiliary Contacts)
You ordered the contactor. Great. Did you order the thermal overload relay? The auxiliary contact block? I've made this mistake more than once. You get the main component and realize you forgot the $15 accessory that makes it work in your circuit.
The worst part is the delay. You rush-order the accessory, pay premium shipping, and your project grinds to a halt for two days. My advice: make a list of required accessories for each contactor type. I now use a spreadsheet that auto-populates the accessories list when I select the contactor model. It's saved me from at least five embarrassing omissions.
I once ordered 20 abb reversing contactors and forgot the mechanical interlocks. That was a $450 mistake plus a week of reordering. Now the interlocks are on my checklist before I click 'buy.'
Step 5: Distinguish Between Relay and Contactor (It's Not Always Obvious)
The difference between relay and contactor seems basic, but in the field, terms get used interchangeably. A colleague once ordered a relay when we needed a contactor for a high-current motor circuit. The result? The relay melted. Total cost: $1,200 in damage and a safety incident report.
Here's my cheat sheet:
- Relays: Lower current (typically under 10A), smaller physical size, often used in control circuits.
- Contactors: Higher current (10A+), larger, designed for motor loads and inductive circuits.
If you're working with motor starters or frequent switching, you almost certainly need a contactor, not a relay. I've had to correct three orders this year where the engineer spec'd a relay instead of a contactor for a motor circuit.
What I mean is that the difference isn't just about current rating—it's about duty cycle and mechanical life. Contactors are built for millions of operations; relays are not. Choose accordingly.
Bonus Tip: Beware of the 'Looks Like' Trap
I've seen people confuse electrical outlet wiring diagrams with contactor wiring. They look similar at a glance—both have terminals labeled L1, L2, L3—but the function is completely different. An outlet's wiring is for distributing power; a contactor's wiring is for switching it.
If you're staring at a wiring diagram and it feels wrong, it probably is. Trust your gut and double-check the source.
Common Mistakes I've Made (So You Don't Have To)
Mistake 1: Ordering 14 abb reversing contactors without confirming the coil voltage. I caught the error after they arrived. $1,200 in returns and expedite fees.
Mistake 2: Assuming a DP contactor 40 A from one series was interchangeable with another series. It wasn't. The mounting holes were different. Caused a 3-day production delay while we fabricated adapters.
Mistake 3: Not verifying the difference between relay and contactor for a motor starter application. Resulted in fried components and a fire risk. Now I keep a reference card in my toolbox.
Industry standard print resolution: 300 DPI at final size for commercial offset printing. If you're printing diagrams or labels for your panels, don't go below 300 DPI. It looks unprofessional and can lead to misreading critical info.
The lowest quote isn't always the cheapest. When I look back at my $3,200 mistake on one order, I realize the 'savings' from skipping verification steps cost me far more than the extra time upfront. Total cost of ownership includes redoing work, delays, and lost trust.
My final piece of advice: use this checklist. Laminate it if you have to. It's saved me from repeating my own mistakes, and I hope it does the same for you.
