A 2 tonne traveling jib crosses eight electrical interfaces before the current reaches the hoist motor. Three of them move. Only one of them is drawn, and it is not the one that fails.
A traveling jib crane carries its own power supply with it. The current crosses three moving joints on the way to the hoist motor: the rail feed that pays cable out and takes it back, the collector in the mast that lets the boom turn, and the wheel-to-rail contact that almost everybody assumes is the earth. NEC 610.61 says the third one does not count as a ground. Most traveling jibs under 2 tonnes ship without the fourth wire that would make it count, and nobody measures it, because the machine is small and small machines are supposed to be simple.
They are not simple. They are just cheap, which is a different thing.
I commissioned a 1 tonne traveling jib in a Vietnamese mould shop in August. Forty metres of track, two rails, a bottom entry collector, single phase 230 V because the panel was already there. The electrician had landed the incoming earth on the mast base plate. It looked right. It measured 3.4 ohm to the building earth bar, because the base plate sat on a shim pack and a coat of epoxy primer. The machine had been running for four months.
That is the whole problem in one sentence: a traveling jib has more places for the supply to degrade than any other crane of its size, and fewer people looking at them.
Because a wheels-on-rails return path is not a ground, and the code stopped pretending otherwise years ago.
NEC Section 610.61 was amended after inspectors kept finding cranes that looked bonded and were not. The current text is blunt about it: the trolley frame and bridge frame shall not be considered as electrically grounded through the bridge and trolley wheels and its respective tracks, and a separate bonding conductor shall be provided. The reasoning given in the code commentary is dirt. Oil, mill scale, paint and grit build up on a running surface, and a contact that measures 0.2 ohm when new measures 8 ohm two winters later.
For a bridge crane that means a fourth conductor in the runway bar. For a traveling jib it means the same thing, on a machine where the cable is the size of a garden hose and the collector ring costs more than the cable. Which is where the corner-cutting starts.
Gorbel writes the requirement on the first page of the manual for their jib cranes, in capitals, because buyers kept asking: the crane cannot be utilized as a ground, a separate ground wire is required, and a three phase system therefore needs three conductors plus one ground wire. That is the manufacturer telling you the frame is not the path. Siemens and Duct-O-Wire both sell enclosed conductor bar with a green cover specifically so the fourth pole can be a protective conductor rather than a live pole.
There is a second reason that has nothing to do with safety codes. A separate PE conductor gives the variable frequency drive a low impedance return. CMAA's position on the fourth rail is that it improves VFD performance and reduces drive faults, because the excess current from a switching event has somewhere to go that is not through a bearing. On a 0.5 to 2 tonne jib with an inverter hoist, that is the difference between a drive that nuisance-trips twice a month and one that does not.
I count eight interfaces on a typical traveling jib. Four of them are detachable, three of them move continuously, and one of them is the one the code says you cannot rely on. Only two appear on a general arrangement drawing.
| Joint | What carries it | How it fails | What we measure |
|---|---|---|---|
| Rail feed (travel) | Festoon on a C-rail, energy chain in a trough, enclosed conductor bar, or a spring reel | Cable jacket worn through at the end clamp or at a rail joint step; trolley wheel flat spots; bar brush dust | Insulation resistance to earth, and a visual at both ends of travel |
| Collector ring (rotation) | Bottom entry or top entry collector, brush or brushless, 3 to 6 ways | Brush dust bridging poles, worn brush, PE way omitted entirely | Resistance per way while turning: 10 to 20 milliohm typical for brush type |
| Wheel to rail (earth) | Four steel wheels on a steel rail, through bearings and grease | Paint, grease and mill scale; rail joints with no bonding clamp | Frame to building earth bar; 0.6 to 4.2 ohm on a painted flange in our readings |
| Pendant and hoist plugs | Two or three IEC 60309 plugs on short leads | Water ingress, missing gland, PE pin bent back to stop a trip | Visual plus continuity on the PE pin |
The rail feed and the collector ring are the two that move continuously. The wheel contact moves too, but it is not supposed to be carrying current, which is exactly the trap. It carries nothing for years, then one day a live conductor touches the frame and it is expected to carry the fault.
The rail feed, and it is not close. Cable and trolley damage accounts for roughly a quarter of the electrical callouts we log on traveling jibs; a missing or badly landed PE is second.
The mechanism is boring and predictable. A festoon trolley runs on a C-rail with a joint every few metres. Each joint has a small step, and every time a trolley crosses it, the wheel takes a hit. Multiply that by the number of traverses in a shift. On a jib doing 200 traverses a day, a trolley crosses 4 joints on a 20 m track, which is 800 impacts a day, 200,000 a year, for a component with a 5 to 8 year design life. The cable suffers worse than the trolley, because the loop that pays out and takes up has a fixed bend point, and the strands at that bend point work-harden.
Conductix derates festoon trolley capacity with speed for this reason. A 63 mm roller carries 125 kg at 100 m/min, 110 kg at 125 m/min, 95 at 160, 85 at 200, and 75 at 250. Same trolley, half the payload, purely because of impact frequency. A slow jib is a forgiving jib.
For a 10 to 40 m jib track, festoon or energy chain. Conductor bar becomes rational past roughly 80 m of travel, and a reel is for the hoist on the boom, not for the track.
| Parameter | Festoon on C-rail | Energy chain | Enclosed conductor bar | Cable reel |
|---|---|---|---|---|
| Installed cost | EUR 25 to 60 per m | EUR 90 to 180 per m | EUR 60 to 200 per m | USD 400 to 1,200 per unit |
| Practical travel | 50 to 150 m | 100 to 200 m | 500 m and beyond, fed in sections | drum capacity, 20 to 40 m |
| Speed | 80 to 120 m/min | more than twice festoon | 200 to 300 m/min | 60 to 90 m/min |
| Service life | cable 5 to 8 years at A4 to A5, 3 to 5 at A6 to A8 | 10 to 15 years | rail 15 to 20 years, brushes 10,000 to 20,000 km | 5 to 10 years |
| Maintenance interval | 6 months, tension and trolley wheels | 12 months, visual only | 12 months, brush wear and rail cleaning | 6 to 12 months, spring and slip ring |
| Cable needed | 1.6 to 1.8 times travel | 1.1 to 1.2 times travel | none | none beyond the drum |
| Best fit on a jib | the default for 10 to 40 m indoor | long, fast, or dirty tracks | very long runs, outdoor, several machines sharing a track | hoist on the boom, below the hook tools |
Cost ranges for festoon and bar come from published 2026 crane electrification guides. Energy chain and reel figures are our own quotation ranges and they move with copper price, so treat them as planning numbers.
Two things in that table matter more than the price column. First, festoon needs roughly 50 percent more cable than an equivalent energy chain, which is a published igus comparison, and on a 30 m track that is 18 extra metres of five core travelling in a loop that has to be stored somewhere. Second, energy chain can run at more than twice the speed of a comparable festoon, which is irrelevant on a jib travelling at 20 m/min and decisive on a track where the machine runs end to end all shift.
Conductor bar is not wrong, it is just over-specified under 40 m. Above 500 m you feed it in sections every 100 to 150 m to fight volt drop, which tells you what the real limit is. If you are choosing between festoon and bar on a 250 USD per metre budget for a 30 m jib, put the bar money into a proper collector ring and a fourth wire and stay with festoon. Our traveling jib crane range ships either way, and the price difference on a 1 tonne machine is about 8 percent.
The 15 year arithmetic is closer than the install price suggests, because the festoon is the only one of the three that has to be replaced three times.
| 15 year cost, 30 m track, 1 t jib | Festoon on C-rail | Energy chain | Enclosed bar |
|---|---|---|---|
| Installed, EUR | 750 to 1,800 | 2,700 to 5,400 | 1,800 to 6,000 |
| Cable or rail replacement, EUR | 1,500 to 4,500, two or three times | 1,400 to 2,900, once | 200 to 600, brushes and shoes |
| Maintenance labour, EUR | 0 to 3,000, six monthly | 0 to 600 | 400 to 1,200, annual |
| Total, EUR | 2,250 to 9,300 | 4,100 to 8,900 | 2,400 to 7,800 |
| Midpoint | 5,775 | 6,500 | 5,100 |
Our planning arithmetic on published unit rates, not a quotation. The midpoints sit within 12 to 20 percent of each other, which is the honest answer: on a 30 m track the feed method is an engineering choice, not a financial one. Choose on the failure mode you can live with, and on whether the cable has to be replaced by somebody on a ladder.
More than the track is long, and that changes the voltage drop calculation before anybody has thought about volts.
| Track travel | Festoon cable, 1.6 to 1.8 times | Energy chain, 1.1 to 1.2 times | Difference |
|---|---|---|---|
| 10 m | 16 to 18 m | 11 to 12 m | 5 to 6 m |
| 20 m | 32 to 36 m | 22 to 24 m | 10 to 12 m |
| 30 m | 48 to 54 m | 33 to 36 m | 15 to 18 m |
| 40 m | 64 to 72 m | 44 to 48 m | 20 to 24 m |
So a 30 m track is a 50 m electrical run. That is the number to put in the volt drop calculation, not 30. It is also the number to put in the copper cost, and the number that explains why the cable on a festoon jib is always longer than the buyer expected when they see it delivered.
Rule of thumb from our own planning sheets: take travel, multiply by 1.7 for festoon, add 3 m for termination at each end, round up to the next cable length you can actually buy.
On three phase, barely. On single phase, it is the thing that will make the crane feel broken.
The formulas differ by one factor and that factor is the whole story. For a single phase circuit the drop is 2 x I x L x (R cos phi + X sin phi) divided by 1000, because current goes out in the line and comes back in the neutral, so the loop is twice the route length. For a balanced three phase circuit it is root three times the same product, because there is no return current in the neutral and the drop is measured between phases. Root three is 1.732. The single phase factor is 2. A single phase load therefore drops 15 percent more than the same load on three phase over the same cable, before you account for the fact that its nominal voltage is 57 percent lower.
Put numbers on it. A 2 tonne jib with a 3 kW hoist and a 0.4 kW travel motor, power factor 0.85 and motor efficiency 0.85, draws about 6.8 A at 400 V three phase and about 20.5 A at 230 V single phase. Twenty amps is not a small crane any more. It is a 32 A blue plug, a dedicated circuit, and a cable that has to be sized for the drop rather than the current.
| Case, 50 m cable route | Current | 2.5 mm² | 4 mm² | 6 mm² |
|---|---|---|---|---|
| 1 t, 230 V single phase | 11.4 A | 4.0 % | 2.4 % | 1.6 % |
| 2 t, 230 V single phase | 20.5 A | 7.1 % | 4.4 % | 2.9 % |
| 1 t, 400 V three phase | 3.8 A | 0.66 % | 0.40 % | 0.27 % |
| 2 t, 400 V three phase | 6.8 A | 1.18 % | 0.72 % | 0.48 % |
Computed at 8.0, 4.9 and 3.3 ohm per km for copper at operating temperature, 230 V or 400 V nominal, against the 5 percent power circuit budget in IEC 60364-5-52 Annex G. SIEC planning figures, not a substitute for the local calculation.
Read the top left cell again. Two point five square millimetre cable on a 2 tonne single phase jib, 50 m route, is 7.1 percent. That is past the 5 percent guidance before the run from the wall panel to the end of the track is counted at all. The crane works, the hoist lifts, and then in winter when the supply sags 4 percent the contactor in the panel drops out mid-lift, and the operator reports that the crane is faulty. It is not faulty. It has been under-fed since the day it was installed.
IEC 60364-5-52 makes the same point from the other direction: if a circuit sits at 8 percent drop at full load, it will see 40 percent or more at start-up. A 20 A circuit with 7 percent at running load is looking at something close to a 45 percent dip on the first half cycle, which will drop a control contactor on any hoist built in the last thirty years.
Because on a small jib it is the cheapest way to sell a machine, and on the customer's side it is usually the socket that already exists.
Single phase is legitimate up to about 1 tonne. Above that you are dragging 20 A through a flexible trailing cable, you are outside the 16 A band that the IEC 61000-3-2 harmonic rules were written around, and you have doubled the volt drop for free. The motor efficiency difference is real but small: a capacitor-start single phase motor runs a handful of points below its three phase equivalent, and at 1.9 kW installed that is tens of watts, not hundreds.
The practical argument is not efficiency, it is cable. Single phase halves the number of live cores and adds a neutral, so a 5 core cable becomes a 3 core, and a 3 core flexible cable is cheaper and much easier to terminate in a collector ring. That is the real reason small jibs are sold single phase, and it is a decent reason as long as the run is short.
Where it stops being a decent reason: any track over 25 m, any machine at 2 tonne, any site where the socket is at the far end of the building, and any site where a second jib will be added later on the same circuit. In those four cases specify three phase and pay for the extra core. It costs less than the cable upgrade you will otherwise buy twice.
It is the one joint that turns every day and gets inspected almost never, and it is where the protective conductor quietly disappears.
A traveling jib needs the boom to rotate through 270 or 360 degrees, and a cable cannot do that indefinitely. The answer is a collector, either bottom entry through the mast pivot or top entry on the boom cap. Bushman lists current collector rings as an option on their 360 degree motorised jibs for exactly this reason, alongside a tagline assembly so the festoon on the boom stays untangled.
The number that surprises people is resistance. A brush type slip ring runs 10 to 20 milliohm per way and that figure fluctuates as it turns, because the brush rides on a ring with a slight eccentricity. A brushless (mercury or inductive) unit sits near 1 milliohm and stays there. For a power pole the difference is irrelevant. For the protective conductor it decides whether your fault loop impedance passes.
| Collector option | Ways | Resistance per way | When we specify it |
|---|---|---|---|
| Brush, 3 way, bottom entry | 3 (L1 L2 L3, no PE) | 10 to 20 milliohm, varies | never on a new machine, still common on imports |
| Brush, 4 way, bottom entry | 4 (3 phase plus PE) | 10 to 20 milliohm, varies | default for three phase jibs |
| Brush, 5 way, bottom entry | 5 (3 phase, N, PE) | 10 to 20 milliohm, varies | three phase plus 230 V control or a socket on the boom |
| Brush, 4 way, top entry | 4 | 10 to 20 milliohm, varies | power arrives along the boom, not up the mast |
| Brushless | 3 to 6 | about 1 milliohm, constant | signal and control circuits, or where a stable PE matters |
Brush dust is the maintenance item nobody schedules. It is conductive graphite sitting inside a small enclosure with line voltage on the next ring, and it bridges given humidity and time. The standard maintenance instruction is dry compressed air plus isopropyl alcohol on the rings, at intervals set by revolutions rather than calendar months, which is why a jib on a busy cell needs it twice as often as the same jib on a slow one.
On the buying side there is one sentence to put in the specification: the collector must carry a dedicated protective conductor, and the machine frame must not be used as the return path. If the quotation says 3 way collector on a three phase machine, the fourth wire has been left for someone else, and that someone will be the customer's electrician, who will land it on the base plate.
At the end of the track, lockable open, in sight of the conductors, and on most small jibs it is simply absent because the code allows it to be.
| Requirement | Where it is written | What it means on a 2 t jib |
|---|---|---|
| Frame not grounded through wheels | NEC 610.61 | a fourth conductor, terminated, measured |
| Runway conductors to include a separate grounding conductor | CMAA practice, quoted in crane inspection standards | 5 pole bar, or a green covered PE pole |
| Disconnect lockable open, within view of the runway conductors, operable from floor level | NEC 610.32, OSHA 29 CFR 1910.306(b)(1) | a lockable switch at the track end, not a breaker in a distant panel |
| Disconnect may be omitted for a monorail hoist or hand-propelled bridge that is floor controlled, in view of the supply disconnect, and has no fixed work platform | OSHA 29 CFR 1910.306(b)(2)(iv) | most 0.5 to 2 t traveling jibs qualify, which is why yours has none |
| A means at the operating station to open power to all motors if the disconnect is not readily accessible from it | OSHA 29 CFR 1910.306(b)(2)(iii) | the pendant emergency stop counts, if it is wired to drop the contactor and not just the drive |
| Supply feeders outside the machine, including flexible cables and conductor bars, are inside the scope | IEC 60204-32:2023, clause 1 | the festoon is the crane maker's electrical equipment, whatever the contract says |
| 5 percent drop for power circuits, 3 percent for lighting | IEC 60364-5-52 Annex G | budget the 50 m cable route, not the 30 m track |
| Double collector shoes on each phase where an adjustable frequency drive or an under-hook magnet is used | crane electrical inspection standard 5.7.6, CSA referenced | a VFD jib needs two shoes per pole, not one |
The exception clause is the interesting one. A traveling jib with a pendant, controlled from the floor, inside sight of its own supply switch, with no fixed platform, does not need a separate disconnecting means. Every one of those conditions is met by a normal 1 tonne jib in a workshop. So the machine arrives with a plug and no isolator, and the person who services it pulls the plug, which is exactly what the code anticipated and exactly what nobody wants to do at 4 m up a mast.
Our own position: fit a lockable isolator at the track end even when the exception applies, and put it where a person standing on the floor can reach the handle without a ladder. It costs USD 200 to 600 and it converts an argument into a procedure.
The other half of this is the plug. IEC 60309 industrial plugs and sockets run 16 to 125 A in IP44 splashproof and IP67 watertight versions, colour coded blue for 230 V single phase and red for 400 V three phase, with switched interlocked socket outlets available. On a jib in a workshop, IP44 is adequate. In a wash-down area, a foundry, or anywhere the track runs past a door, specify IP67, because the plug hangs on the machine at the height where everything gets hit. We see water and dust ingress at the plug as the third most common electrical fault on these machines, and it is a 60 to 200 USD part.
No, and saying so saves buyers a pointless filter.
A traveling jib in the 0.25 to 2 tonne range sits between roughly 1.4 A and 6.8 A per phase at 400 V, well inside the 16 A limit that defines the IEC 61000-3-2 band. The IEC 61000-3-12 rules for equipment above 16 A and up to 75 A per phase simply do not apply, and neither do the IEEE 519 point-of-common-coupling limits unless the same board is feeding something much larger. One small jib cannot move the voltage distortion at a PCC.
What it can do is generate transients, and that is a different failure. Every time a collector shoe crosses a rail joint, contact is interrupted for a fraction of a cycle. With a contactor hoist you never notice. With an inverter hoist, the drive sees a supply dip, the DC link sags, and depending on the drive you get a trip, a re-start, or a logged undervoltage event that nobody reads until the third one in a week. This is why the double-shoe rule exists for AFD machines and why CMAA pushes the fourth rail for drive performance. The fix is mechanical contact, not filtering.
If you do have an inverter hoist on a jib, two additions are worth the money and neither is a filter: a type B residual current device on the dedicated circuit, because the drive's EMC filter puts smooth DC on the protective conductor and a type A device will not see it, and a 4 percent line reactor if the same board feeds other drives. Both are covered in more detail in the jib crane drive options, but the short version is that a 2 tonne machine does not need harmonic mitigation. It needs good contacts.
Seven failure modes account for essentially everything we are called out for on traveling jibs under 2 tonnes. This distribution is from our own service records for 2023 to 2026 and it is not a published statistic, so treat it as a pattern rather than a benchmark.
| Failure | Share | Usual cause | Prevention |
|---|---|---|---|
| Festoon cable or trolley damage | 27 % | impact at rail joints, cable pinched at the end clamp | align joints, add a strain relief loop, inspect both ends |
| PE missing or landed on the frame | 21 % | 3 way collector, or earth tail bolted to a painted base plate | 4 way collector plus a measured reading at handover |
| Water or dust at plug and socket | 15 % | IP44 plug hanging at 1.5 m in a wet bay | IP67 plug and switched socket, cable gland fitted |
| Isolator absent, not lockable, or out of sight | 12 % | exception clause used, or a breaker indoors | lockable switch at track end, floor reachable |
| Collector dust, intermittent control | 10 % | no PM schedule, dust bridging between ways | clean by revolutions, not by calendar |
| Nuisance RCD trip | 9 % | type A device on a VFD hoist, or a shared lighting circuit | type B device, dedicated circuit |
| Rail joint earth continuity above 1 ohm | 6 % | no bonding clamp at the joints | bond every joint, measure at handover |
The two biggest items share a property: both are visible if you look, and neither is looked at. A festoon cable wears at a bend point 4 m above the floor. A PE tail lands on a base plate behind the mast. Both are ten minute checks and both are skipped because the machine works.
Cheap, relative to the crane. All of the following are our 2026 quotation ranges and they assume the machine is already installed.
| Item | USD | Fixes |
|---|---|---|
| 4 mm² bonding jumper with crimped lugs | 40 to 150 | a frame that looks earthed and is not |
| Rail joint bonding clamp, each | 15 to 40 | earth continuity across the joints |
| IP67 plug and switched interlocked socket, 16 A | 60 to 200 | ingress and a plug that pulls out under load |
| Lockable rotary isolator, 16 to 32 A, IP65 | 200 to 600 | servicing without pulling a plug 4 m up |
| Type B RCD, 4 pole, 30 mA | 250 to 700 | nuisance trips on a VFD hoist |
| 4 way collector ring, bottom entry | 380 to 950 | a 3 way collector with no PE |
| Enclosed conductor bar, 5 pole, installed | 55 to 95 per m | festoon wear on a long or hot track |
| Energy chain conversion with guide trough | 90 to 180 per m | repeat cable replacement and speed limits |
| Collector and earth inspection, annual | 150 to 400 | finding the next fault before the shift does |
Spend in this order. Bonding and a measured reading first, because that is the safety item and it is the cheapest. Then the collector PE way, because a 3 way collector on a three phase machine is a defect that will not fix itself. Then the isolator, then the plug, then anything to do with the festoon. If you are replacing a festoon anyway, price an energy chain at the same time: the 15 year arithmetic on a 30 m track usually comes out within 20 percent either way once three cable replacements are counted, and the energy chain removes the joint-impact failure mode entirely.
Seven readings. Give them to the customer in writing, with the instrument type and the date, and the argument about whether the crane was ever earthed properly stops before it starts.
| Reading | Instrument | Expected at handover | Investigate above |
|---|---|---|---|
| Frame to building earth bar | Four wire low resistance meter | below 0.1 ohm | 1 ohm |
| Insulation resistance, live to PE | 500 V DC insulation tester | above 1 megohm | 1 megohm |
| Collector resistance per way, boom turning | Micro-ohmmeter | 10 to 20 milliohm brush, near 1 brushless | 50 milliohm, or swinging by more than double |
| Voltage at hoist terminals, rated load lifting | Voltmeter and clamp | within 5 percent of nominal | 5 percent |
| Continuity across each rail joint | Low resistance meter | below 0.05 ohm with a bonding clamp | 0.1 ohm |
| RCD trip time at rated residual current | RCD tester | under 300 ms | no trip at all |
| Photograph of each termination | Phone | PE tail on a dedicated stud, not a base plate | cannot see it |
Six of those seven take a few minutes each. The photographs are the ones that get used two years later when the machine changes hands or an inspector asks why the frame reads 3.4 ohm.
| # | Line to put in the enquiry |
|---|---|
| 1 | Supply voltage, phases and frequency at the track end, not at the building intake |
| 2 | Track travel length in metres, and the distance from the panel to the track end |
| 3 | Feed method: festoon, energy chain or conductor bar, and who supplies the track |
| 4 | Collector ways, and confirmation that one way is a dedicated protective conductor |
| 5 | Rotation angle, and whether rotation is manual or motorised |
| 6 | Plug and socket standard, IP rating, and who provides the socket |
| 7 | Isolator: lockable, at the track end, in sight of the conductors, floor operable |
| 8 | RCD type required, and confirmation of whether the hoist is inverter or contactor controlled |
| 9 | Rail joint bonding: included or by others |
| 10 | Handover pack to include measured earth continuity, insulation resistance and collector resistance per way |
Line 10 is the one that changes behaviour. A pack with readings in it means the next person who services the machine starts from a number instead of an assumption, and it costs twenty minutes at commissioning. Everything else on the list is a sentence in an email. That one is the difference between a machine that is safe and a machine that is believed to be safe.
No. NEC 610.61 states that the trolley frame and bridge frame shall not be considered electrically grounded through the wheels and their tracks, and that a separate bonding conductor shall be provided. Gorbel puts the same instruction in the installation manual for their jib cranes: the crane cannot be used as a ground, so a three phase machine needs three conductors plus one ground wire. On a traveling jib the practical consequence is a 4 way collector rather than a 3 way one. If your quotation says 3 way on a three phase machine, the protective conductor is missing.
Not automatically, but check the run. A 2 tonne jib with a 3 kW hoist draws about 20.5 A at 230 V, which already needs a 32 A circuit and a 32 A blue plug rather than the 16 A one usually supplied. Over a 30 m track the cable route is about 50 m including the festoon loops, and 2.5 mm² cable gives 7.1 percent drop against a 5 percent budget. Go to 6 mm², or go to three phase. The three phase version of the same machine sits at 1.2 percent on the same cable.
Legally, in many jurisdictions, no. OSHA 29 CFR 1910.306(b)(2)(iv) allows the disconnecting means to be omitted where a monorail hoist or hand-propelled crane bridge is controlled from floor level, is within view of the power supply disconnecting means, and has no fixed work platform. Most small traveling jibs meet all three. We still recommend a lockable isolator at the track end, because pulling a plug at head height to change a collector brush is how people get hurt. It is a 200 to 600 USD part.
Either. Festoon costs EUR 25 to 60 per metre installed against EUR 90 to 180 for an energy chain, but festoon needs about 50 percent more cable and the cable is a wear item at 5 to 8 years on A4 to A5 duty. Over 15 years with three cable replacements the totals land within about 20 percent of each other. Choose festoon if the track is short and the machine is slow, choose the chain if the machine runs continuously, if the track is dirty, or if the speed is above 100 m/min, which is where festoon trolleys start to derate.
Because the leakage is marginal and something else on the circuit moves it over the threshold, and because an inverter hoist puts smooth DC on the protective conductor that a type A device cannot see. Fit a type B device on a dedicated circuit. If the machine is contactor controlled with a half-wave brake rectifier, a type A device does detect the pulsating DC, so the trip is more likely to be a shared circuit with LED drivers or a charger. Either way, clamp the standing leakage with the crane off and again with it on before buying anything.
Three things, in this order. Measure resistance from the crane frame to the building earth bar with a low resistance meter, not a multimeter, and anything above 1 ohm means the path runs through paint or a shim. Then look at the collector: brush dust, brush length, and whether there is a fourth way at all. Then look at both ends of the festoon, where the cable is clamped, because that is where the jacket wears. The full electrical section of our traveling jib crane documentation lists the readings we expect at handover, and they are the same readings to take a year later.
Related articles:
Traveling Jib Crane Energy Consumption: Where the Watts Go on a 0.25 to 2 Tonne Machine
Suspension Crane Power Quality: Why an Underhung Crane Is Really Part of the Building
Crane Power Quality: What a Single Girder Crane Does to a Weak Grid
Crane Harmonic Distortion: What Five Drives on One Busbar Do to a Double Girder
Traveling Jib Crane Installation: Rail, Anchors and the Load Test