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Replace the contact kit in a motor starter or contactor when the contact material is worn thin, when the contact faces are deeply pitted or burnt, when a contact has welded, or when the poles are wearing unevenly. Dark, discolored contact faces on their own are normal and are not a reason to change the kit. The way to know is to open the contactor and look, because the outward symptoms of worn contacts are shared with other faults.
A contact kit is the set of replacement main contacts for one contactor or starter size. This guide explains why contacts wear, what to look for at inspection, how to pick the right kit, and which motor control families the BRAH Electric contact kits cover.
Contact kit wear at a glance
- Contacts wear every time the contactor opens or closes under load. Wear is expected. The question is how much.
- Replace on condition: thin or missing contact material, deep pits or craters, burnt or melted areas, welding, or uneven wear between poles.
- Discoloration and a slightly rough surface are normal on contacts that have been in service.
- Replace all poles together, using a kit made for the exact contactor family, size and pole count.
- Always inspect the contacts after the starter has cleared a short circuit.
- BRAH lists 183 contact kits across 18 families, all listed at 600V maximum. Contact kits carry a 6-month warranty.
What a contact kit is and why contacts wear
The main contacts carry the motor current while the contactor is closed, and they make and break that current each time it operates. Each pole has moving contacts on the armature and stationary contacts in the base. A kit replaces them. Most kit descriptions in the BRAH catalogue read “complete assembly kit includes all contacts and related mounting screws and hardware”.
When contacts part under load, the current keeps flowing for an instant as an arc. The arc is hot enough to vaporize a small amount of contact metal at each operation. Closing does damage too: the contacts can bounce as they meet, and each bounce draws a short arc while the motor is taking its starting current. Over thousands of operations the contact tips lose material, the surfaces roughen, and metal moves from one face to the other.
How fast this happens depends on the duty. A contactor that starts a motor a few times a day wears slowly. One that is jogged, plugged or cycled constantly wears quickly, and one that has had to open on a fault can be damaged in a single operation. Larger contactors have arc chutes over the contacts to cool and put out the arc. What they do is covered in the guide to arc chutes.
Signs at inspection that the contacts need replacing
With the contactor isolated and opened, look at every pole. Replace the kit when you find any of these:
- Contact material worn thin. The contact tip is nearly gone, or the backing metal underneath is showing.
- Deep pitting or craters. Light, even roughness is normal. Deep holes, raised lumps of transferred metal and ragged edges are not.
- Burnt or melted areas. Signs of overheating on the contacts, the contact carrier or the plastic parts around them.
- Welding. Contacts that have stuck together, or that show torn metal where a weld broke free.
- Uneven wear. One pole clearly worse than the others, or contacts that no longer meet squarely.
- Damaged hardware. Broken or weak contact springs, loose screws or cracked contact holders.
Do not judge by color. New contacts darken quickly in service, and a black or grey film does not mean they are finished. If the manufacturer of the contactor gives a wear limit or a renewal instruction, follow it.
Operating symptoms that call for an inspection
These symptoms do not prove the contacts are worn. Each has other possible causes. They are reasons to isolate the starter and look.
| Symptom | What it can mean at the contacts | What else to check |
|---|---|---|
| Contactor stays closed after the coil is de-energized | Welded contacts | A mechanical jam in the armature, or a control circuit that is still feeding the coil |
| Heat at the contactor or its terminals | High resistance across worn or burnt contacts | Loose or corroded terminations, undersized conductors |
| Motor runs rough, hums or trips the overload relay | One pole not making, so the motor is running on two phases | A blown fuse, a supply fault, or the motor itself |
| Chatter or buzzing from the contactor | Contacts arcing as the contactor fails to seal | Low control voltage, a failing coil, or dirt on the magnet faces |
| Burnt smell, smoke marks or flash marks | Heavy arcing at the contacts | A damaged arc chute or tracking on the insulation |
If the overload relay is tripping, work through it before changing parts. The guide to troubleshooting an overload relay covers that side of the starter.
Contact kits BRAH lists, by family
The table groups the BRAH contact kits by the OEM brand and family they are made for. The equipment column gives the model types named in the catalogue descriptions. Sizes are the NEMA or IEC starter sizes named for that family. Each row links one example kit. The rest of the family is in the contact kits listing.
| Brand and family | Equipment named | Starter sizes named | Amperage (catalogue) | Poles | Kits listed | Example kit |
|---|---|---|---|---|---|---|
| Allen-Bradley Bulletin 500 Line | Types 500, 505 and 509 | NEMA 0 to 5 | 18A to 270A | 1 | 6 | B40420-322-51 |
| Allen-Bradley Series K | Types 702, 705 and 709 | NEMA 0 to 4 | 18A to 135A | 1 | 5 | BZ34039 |
| Asea A-Line | A, AE and AF contactors, A50 through AF2050 | Listed by contactor model | 80A to 2000A | 3 | 18 | BZL75 |
| EH Series | EH-100 through EH-1200 contactors | Listed by contactor model | 120A to 1200A | 3 | 13 | BEHCK210-3 |
| Cutler-Hammer Citation Series A1 | Model types A10 to A81 and C10 to C50 | NEMA 0 to 7 | 18A to 810A | 2, 3, 4, 5 | 16 | B6-22-2 |
| Cutler-Hammer Citation Series B1 | Model types B10, B11, B50, B51 and B52 | NEMA 2 to 4 | 45A to 135A | 2, 3, 4, 5 | 10 | B6-34-2 |
| Cutler-Hammer Freedom Series | Model types AN16, AN30, AN40, AN70, AN80, AN800, CN15, CN35 and CN55 | NEMA 1 to 5; IEC L, N | 27A to 270A | 3 | 7 | B6-65-2 |
| Furnas Innova | Model types in the 14, 22, 40 and 43 series, such as 14DF and 40HF | NEMA 0 to 5; IEC H | 18A to 270A | 1 | 13 | B75FF14 |
| Furnas and Siemens 3TC | 3TC44, 3TC48, 3TC52 and 3TC56 contactors | IEC 2, 4, 8, 12 | 45A to 1215A | 3 | 4 | B3TY2520-0A |
| Furnas and Siemens 3TK | 3TK48, 3TK50, 3TK52, 3TK54 and 3TK56 contactors | Listed by contactor model | 100A to 400A | 3 | 5 | B3TY7480-0B |
| General Electric 200 Line and 300 Line | CR105, CR106, CR109, CR205, CR206, CR209, CR305, CR306 and CR309 | NEMA 0 to 5 | 18A to 270A | 3, 4 | 10 | B546A780G002 |
| Siemens Sirius | 3RT10 contactors, 3RT1033 through 3RT1075 | Listed by contactor model | 32A to 400A | 3 | 13 | B3RT1955-6A |
| Siemens World Series | 3TF44 through 3TF57 and 3TB44 through 3TB58 contactors | NEMA 1 to 6 | 32A to 630A | 3 | 23 | B3TY7480-0A |
| Square D Class 9998 | Model types such as 8502SD and 8536SD, SB through SH | NEMA 0 to 6 | 18A to 540A | 2, 3, 4 | 14 | B9998SL-4 |
| Telemecanique TeSys D | LC1D115 and LC1D150 contactors | Listed by contactor model | 250A | 3 | 1 | BLA5D1158031 |
| Telemecanique TeSys F | LC1F115 through LC1F800 contactors | Listed by contactor model | 250A to 1600A | 3, 4 | 9 | BLA5FG431 |
| Westinghouse A200 Series | A200, A201, A210 and A211 | NEMA 0 to 6 | 18A to 540A | 1, 3, 4, 5 | 10 | B373B331G12 |
| Westinghouse Advantage W200 | W200M1 through W200M6 | NEMA 1 to 6 | 27A to 540A | 3 | 6 | BWCK33 |
The amperage column is the range of catalogue ratings in that family. It is not a motor rating for your application, so match the kit to the nameplate of the contactor. A pole count of 1 means the kit is listed per pole. BRAH Electric is an aftermarket manufacturer and is not an authorized distributor of these OEM brands. For anything not in the table, call (855) 355-2724 with the part number.
How to pick the right contact kit
Three facts identify a kit: the equipment it goes into, the size of that equipment, and the number of poles.
- Equipment. Read the brand, family and model type from the contactor or starter nameplate. The same NEMA size uses different kits in different families. A size 2, 3-pole Cutler-Hammer starter takes one kit in the Citation Series A1 family and another in the Freedom Series.
- Size and amperage. Read the NEMA or IEC size from the nameplate and compare the amperage with the catalogue rating of the kit. As an example, the BRAH kit for a NEMA size 0 Citation Series A1 starter is listed at 18A.
- Poles. Count the power poles. Kits are listed as 1, 2, 3, 4 or 5 pole. Where a kit is listed per pole, order one for each pole so that all poles are renewed together.
- The OEM kit number. If the starter door, the parts list or the old kit carries a renewal part number, search for that number. BRAH kit numbers are the OEM number with a B in front.
A worked example for one part is in the guide to the Cutler-Hammer 6-22-2 contact kit.
Before you order: what to check
- The nameplate data of the contactor or starter: brand, family, model type and size.
- The pole count, and whether the kit is listed per pole or as a full set.
- The condition of the coil, the arc chute and the terminals. If the contactor body is cracked or the magnet is damaged, new contacts will not make it serviceable.
- The cause of the wear. Contacts that wore out quickly point to a duty or control problem, such as rapid cycling or low control voltage, that will wear the new kit the same way.
Contact kits carry a 6-month warranty from the date of invoice. Returns are accepted within 30 days of shipment with an RMA and are subject to a restocking charge of 25 to 50 percent. In-stock orders placed before 3:00 PM Pacific ship the same business day. BRAH Electric designs its parts in-house and tests them at its Carlsbad, California facility.
Safety when inspecting or changing contacts
Inspecting contacts means opening a device that is connected to line voltage. De-energize the starter, apply lockout/tagout to the power source and to any separate control supply, and verify the absence of voltage before touching it. The work should be done by qualified personnel. Do not operate a contactor under load with its arc chute or cover removed.
Contact kit FAQs
How often should contact kits be replaced?
There is no fixed interval. Wear depends on how often the contactor operates and what it switches. Inspect the contacts as part of your scheduled electrical maintenance and after any fault, and replace them on condition.
Are black or discolored contacts worn out?
Not by that sign alone. Discoloration is normal. Look for loss of contact material, deep pitting, burning or welding.
Can I replace the contacts on one pole only?
It is better to renew all poles together. New and worn contacts side by side close unevenly, and the worn poles will soon need the same work.
Should worn contacts be filed smooth?
Follow the contactor manufacturer’s instructions. Filing removes contact material, and contacts that are worn enough to need reshaping are usually due for replacement.
What happens if a worn contact kit is left in service?
Resistance and heat at the contacts rise, and the risk grows that a pole fails to make or that the contacts weld. A motor running with one pole open is running on two phases, which overheats it.
How do I find the BRAH kit for my contactor?
Search for the OEM kit number, or use the table above to find the family and then browse the contact kits listing. For help with a cross-reference, call (855) 355-2724, Monday to Friday, 6AM to 5PM Pacific.
References
- NFPA 70B, Standard for Electrical Equipment Maintenance. Covers maintenance programs for electrical equipment.
- IEC 60947-4-1, Low-voltage switchgear and controlgear: electromechanical contactors and motor-starters.
- OSHA 29 CFR 1910.147, The control of hazardous energy (lockout/tagout).
- NFPA 70E, Standard for Electrical Safety in the Workplace.