Rittal Enclosure Sourcing Checklist: 8 Checks I Run Before Every Order

Why I Started This Checklist

The most expensive sentence in enclosure sourcing is, “I’ve ordered these enough times to know what I’m doing.”

In May 2019, I bought 22 wall-mounted enclosures for a food-processing line. Width was right. Height was right. Price was acceptable. The only problem was the installation area: it sat about four meters from a daily caustic washdown station. Six months later, the door seals had started to degrade, and moisture had worked its way into one contactor. That mistake cost roughly $4,300 in replacement work and a two-week delay on commissioning.

I’m an electrical engineer. Since 2015, I’ve handled Rittal enclosure and Rittal enclosure cooling purchases for an OEM panel shop — filter fans, heat exchangers, cooling units, heaters, and every accessory that goes with them. I’ve documented 19 significant mistakes that added up to about $27,000 in wasted budget. Most weren’t dramatic failures. They were the same few errors repeated: wrong environment assumption, wrong heat-load guess, missing accessory lead time, missing paperwork.

This checklist is for anyone sourcing electrical cabinets for machine builders, industrial plants, or their own product line. If you don’t have a repeatable process yet, start here. There are eight checks.

Check 1. List What the Enclosure Must Survive Before Choosing a Rating

Open a catalog after you open a notepad. Write down every environmental hazard the cabinet will face, not just the ones on the electrical drawing.

• Indoor or outdoor, and does rain or direct sun hit the enclosure?
• Is there washdown, hose-down, or high-pressure cleaning nearby?
• Is the atmosphere dusty, salty, humid, or chemically aggressive?
• Will the enclosure sit in a hot area with poor airflow?

Then look at the actual protection rating. IP codes are tested to IEC 60529, while NEMA/UL Type ratings have their own test methods in NEMA 250 and UL 50E. The common claim that “IP54 equals NEMA 12” is only approximate. The tests are different, and the results are not fully interchangeable.

It’s tempting to reduce all of this to one IP number. But an IP rating does not tell you whether a painted mild-steel cabinet will survive caustic cleaning agents. That is a material and coating question. Sometimes the right answer is stainless steel, not just a “higher IP” version of the same box.

Check 2. Calculate Heat Load in Watts Before You Spec Rittal Enclosure Cooling

I don’t guess cooling anymore. I add up the heat that the components will actually dissipate — drives, transformers, contactors, busbars, and even some control devices. The number on the motor nameplate is not the heat number. A variable-frequency drive’s datasheet usually lists power loss in watts. Use that.

If the cabinet is outdoors, add solar heat gain through the enclosure surface. If it’s indoors near a furnace or a press, measure the area around the cabinet, not the average temperature of the building.

Remember: filter fans do not create cold air. They exchange cabinet air with plant air. If the plant air is 43°C and your maximum internal temperature is 40°C, no fan-and-filter combination will get you there. That is when you move up to a Rittal enclosure cooling unit or a heat exchanger designed for closed-loop cooling.

In 2021, I sized a fan-and-filter set based on the cabinet volume, not the actual heat load. The enclosure ran above 50°C on a hot afternoon, and the drives were derating at the worst possible time. The retrofit cost us about $3,900. The fans weren’t defective. They were the wrong solution.

Check 3. Check Usable Depth and Door Swing, Not Just Width and Height

Width and height are the first numbers everyone checks. Depth is the one that gets ignored until something doesn’t fit.

In 2022, I ordered seven large enclosures for a water-treatment project. The width and height were correct. What I missed was the customer’s cable tray layout. Once the enclosures were mounted, the door could only open about 65 degrees because a cable tray ran too close on the hinge side. The technician couldn’t pull the internal swing frame out far enough to work comfortably.

So I now ask two questions before ordering:

• What is the usable depth after the mounting plate, cable ducts, and back-wall clearance?
• How much clearance does the door need to open fully in its final location?

Draw a side cross-section if you have to. It takes ten minutes and it catches problems that a top view never shows.

Check 4. Order Accessories in the Same Batch as the Enclosures

The fastest way to turn a three-day job into a three-week job is to order enclosures first and accessories later. Mounting plates, gland plates, plinths, earthing kits, door handles, and internal cable management all have their own lead times.

In early 2024, we ordered twelve enclosures and assumed the plinths would arrive with them. The enclosures showed up in four days. The plinths took three weeks because they were on a separate order status. The team had already started wiring. When the plinths finally arrived, we had to partially disconnect and lift enclosures that were already populated. That was not a failure. It was just a stupid $1,600 delay.

Now every request for quote must include the full assembly list: enclosure, mounting plate, gland plates, plinth, locks, and any internal mounting hardware. If something has a longer lead time, I want to know before I send the PO, not after.

Check 5. Settle Drawing Approvals and Documentation Before the PO

This is the step most people skip because it feels administrative. Then it becomes an emergency.

Before I order, I ask: who approves the enclosure drawing, and what documentation must ship with the cabinets? Some customers require datasheets, material declarations, or test reports. Others want a signed drawing revision. It sounds simple, but I’ve ordered cabinets based on revision 1 while the customer had already approved revision 2. The difference was a set of extra cutouts that we then had to modify in our workshop. That modification cost us about $900 and most of a Friday.

The checklist point is not just “get the drawing approved.” It’s “confirm which revision is approved and make sure the supplier quotes against that revision.” Documentation and approval requirements should be part of the request for quote, not an afterthought.

Check 6. Decide Whether You Need Electrical Cabinet OEM or Private Label Before You Brand It

People use the terms interchangeably, but they are not the same decision.

An electrical cabinet OEM arrangement usually means the cabinet is built to a design you own, approve, or develop jointly. You are the original equipment manufacturer of the final product, and the enclosure manufacturer is your production partner. A private label arrangement usually means the enclosure manufacturer produces a product under your brand — sometimes a standard design, sometimes customized — and you sell it as your own.

Both models can make sense. But the question has to be asked early, because both involve minimum quantities, lead times, approved drawings, branded nameplates, special paint colors, packaging, and revision control.

The mistake I see is waiting until after a product launch or a customer bid, then asking whether the enclosure can be private labeled. The answer usually involves rework, new drawings, and a lead time that doesn’t fit the schedule.

If you only need a logo on a standard product, that is one conversation. If you need a modified cabinet with your brand and your part number, that is a different project. Start the conversation before you commit to a delivery date.

Check 7. Evaluate the Electrical Enclosure Supplier on Total Cost, Not Unit Price

My opinion after eleven years: the cheapest quote is the cheapest only if everything goes right. When something goes wrong, the cheapest quote can become the most expensive order of the year.

In 2023, we tested two suppliers on the same enclosure specification. The lower quote looked attractive, but the supplier could not answer basic questions about delivery packaging, document timelines, or what would happen if a cabinet arrived damaged. We went with the supplier who cost more per unit but answered those questions clearly.

That didn’t feel exciting at the time. It saved us later when one batch arrived with freight damage and the replacement process took two days instead of two months.

When I evaluate an electrical enclosure supplier now, I ask four things:

• Do they carry the full accessory range, or only the main enclosures?
• What is their actual process for damaged deliveries?
• Can they provide drawings and technical documents before shipment?
• What happens if we need an urgent replacement part mid-project?

A $200 price difference disappears the moment you lose a full day of installation labor.

Check 8. Run the Checklist Twice: Once Before Approval, Once Before the PO

A checklist only works if you actually use it at the right moment. The right moment is not when the order arrives. It’s before the purchase order leaves your desk.

At my current company, no enclosure PO goes out until one other person has signed the checklist. That sounds bureaucratic. But it caught three wrong part numbers in the first six months — not because the engineer was careless, but because enclosure system naming can be brutally similar.

The process is simple: I complete the technical review, mark all eight checks, then send it to a colleague who wasn’t involved in the earlier discussions. They look for assumptions, not just typos. It takes about fifteen minutes. It has saved us far more than that in rework.

Three Mistakes That Still Catch People

Even with a checklist, a few issues keep coming back.

The first is condensation. If a cabinet sits in a location with big temperature swings, a cooling unit might not be enough. Sometimes the right thermal management product is a small heater or a thermostat-controlled anti-condensation heater. Thermal management is not one-way.

The second is cable entry. Gland plates and bottom entry zones need to be planned during the drawing phase. If you leave cable entry for the installation team, someone will cut a hole in the wrong place and void the protection rating of the enclosure.

The third is modification control. If the supplier performs custom cutouts, confirm the revision in writing. “Same as last time” is not a specification. It is how last time gets repeated, including the mistake.

I can’t un-order those 22 enclosures from 2019. But I can keep the next order from becoming another entry on the mistake list. The checklist is cheap. The rework is not.