Comb Busbar Sizing and Compatibility
A comb (pin) busbar distributes phase and neutral to a row of DIN-rail devices through one insulated strip instead of a jumper wire between every terminal. Fewer connection points means faster assembly and less risk of a loose or missed jumper -- but only if the comb's pin pitch and current rating actually match the devices it feeds. This page covers the sizing logic, not cable labelling or marking, which is covered elsewhere.
How comb busbar sizing works
Map the device row
List every MCB, RCBO or other DIN-rail device in the row, in order, noting manufacturer and series -- a comb only works across devices it was designed to feed.
Match the pin pitch
Confirm the comb's pin pitch against the device series' terminal spacing; mixing incompatible pitch and series is a common, avoidable assembly error.
Check the current rating
Read the comb's rated current from the manufacturer's datasheet against the row's actual load -- this is never a generic number, it's specific to the product chosen.
Decide comb or point-to-point
Where the row is uniform and long enough, a comb pays off; where devices are mixed brands, irregular, or few in number, point-to-point wiring is still the right call.
What actually drives the sizing decision
Comb busbars replace individual jumpers
Instead of wiring phase and neutral to each device separately, one insulated comb strip feeds an entire row -- fewer terminals to tighten, fewer places for a connection to work loose.
Pin pitch is series-specific
Each device manufacturer or series has its own terminal spacing; a comb built for one series will not seat correctly on another, even if both are 'standard' DIN-rail devices.
Current rating comes from the datasheet
A comb's current-carrying capacity is a rated figure from its manufacturer, not a universal number -- it depends on the comb chosen and the load it carries, so it always follows from the quote or datasheet, not a generic listing.
Point-to-point still has its place
Irregular layouts, mixed-manufacturer rows, or a handful of devices where a comb wouldn't pay off are still wired point-to-point -- the busbar is a method choice, not a default.
Enclosure conditions affect current-carrying components
Devices and busbars run warmer in a sealed enclosure than a ventilated one; manufacturers publish derating tables for exactly this, and enclosure choice feeds back into how a row is sized.
Fewer connections, fewer failure points
Every jumper wire is a terminal that can be tightened wrong or missed; consolidating a row onto one comb strip reduces the connection count without changing what the row does electrically.
What we check before we spec a comb
Our engineers review the actual device row before recommending a busbar or point-to-point wiring.
- Device-by-device compatibility check
- Pin pitch and manufacturer verification
- Current rating cross-checked against datasheet
- Point-to-point wiring where a comb isn't suitable
- IEC 61439 assembly documentation
Frequently asked questions
What is a comb (pin) busbar?
It's an insulated strip with pins spaced to match a DIN-rail device series, feeding phase and/or neutral to a whole row of devices from one connection point instead of a separate jumper wire to each.
How is the pin pitch determined?
Pin pitch is set by the device manufacturer and series -- it's read from the datasheet or device documentation, not assumed; mismatched pitch is the single most common comb-sizing mistake.
What sets the comb's current rating?
The manufacturer's datasheet for that specific comb, based on its cross-section and the number of devices or poles it feeds. We don't quote a generic amperage -- it depends on the product and the project.
When should point-to-point wiring be used instead?
When the row mixes manufacturers or series, has irregular spacing, or is too short for a comb to pay off in assembly time -- jumper wires remain the correct, standard method there.
Does this cover cable labelling or marking?
No -- labelling and cable marking are a separate topic covered on our panel assembly and DIN-layout pages; this page is only about the busbar-vs-jumper-wire method and sizing decision.
Not sure whether a comb fits your row?
Send us your device list and layout -- we'll confirm compatibility, sizing and whether point-to-point wiring makes more sense for your project.