Site work & quality
Site power: 230 V, 400 V, cables and generators
When a welding machine requires 400 V, how long extension cables can be, and what output the generator must deliver.
When 230 V is sufficient
Up to around Ø355 mm, most butt fusion welding machines can operate on standard 230 V. Power consumption is distributed between the heating element, planer and hydraulics, and the total load typically ranges between approx. 2.5 and 5.5 kW in this size range – i.e. more than a standard 10 A circuit can deliver over a prolonged period.
Therefore, the socket outlet must be fused as specified in the manual, usually 16 A. A 13 A circuit or a socket on a shared circuit may withstand a brief weld, but will trip when the heating element and planer operate simultaneously with the hydraulics.
When 400 V is required
From around Ø500 upwards, the machines normally require 400 V three-phase with earth, and power requirements increase with diameter: approx. 6.5-7 kW at Ø500, approx. 11-12 kW at Ø630, approx. 17-18 kW at Ø800, approx. 21-24 kW at Ø1000-Ø1200 and approx. 43 kW at Ø1400-Ø1600.
The connection must be 16 A medium time-delay as a minimum on the smaller 400 V machines, using a cable of at least 2.5 mm² and an approved CEE plug. Large machines should have a dedicated circuit – they must not share a supply with compressors, hot-air blowers or power tools.
For electrofusion welding, it is not the continuous power demand over time but the peak inrush current that is critical. Allow for at least approx. 3.2 kW for fittings up to approx. d160 and 4-5 kW for larger fittings, and use a regulated generator as specified when welding large fittings.
Extension cables: length and cross-section
Long and thin cables cause voltage drops, and a voltage drop is precisely what causes a machine to abort mid-weld. Rules of thumb for 230 V systems are approx. 20 m at 1.5 mm², approx. 75 m at 2.5 mm² and approx. 100 m at 4.0 mm² – and these are maximum limits, not recommendations.
Always use cable with the correct cross-section and an approved rating for outdoor use. The cable must be fully unreeled from the drum: a partially unreeled cable on a drum will heat up and can melt the insulation, even when the electrical load is within allowable limits.
The same principle applies to 400 V. Check the voltage at the machine if using a long cable, and prefer moving the machine closer to the supply over extending the cable further.
| Machine | Power supply | Typical power | Fuse / Breaker protection |
|---|---|---|---|
| Butt fusion welding up to approx. Ø355 | 230 V, 50 Hz | approx. 2.5-5.5 kW | 16 A (time-delay) |
| Butt fusion welding approx. Ø500-Ø630 | 400 V 3P | approx. 6.5-12 kW | 16 A medium time-delay, min. 2.5 mm² |
| Butt fusion welding approx. Ø800-Ø1200 | 400 V 3P | approx. 17-24 kW | Dedicated circuit, 16 A medium time-delay |
| Butt fusion welding approx. Ø1400-Ø1600 | 400 V 3P | approx. 43 kW | Dedicated circuit, check connection with an electrician |
| Branch/saddle equipment, large | 400 V 3P | approx. 9 kW | 16 A medium time-delay, min. 2.5 mm² |
| Electrofusion welding | 230 V or 400 V depending on control unit | peak load, approx. 3.2-5 kW | Follow control unit instructions, see service |
Indicative power and rating levels. Always check the machine nameplate and manual – and have an electrician assess fixed installations. See also the checklist and service and maintenance.
Generators: size according to starting current, not the nameplate
A generator must be capable of delivering both continuous power and the inrush currents generated when starting the heating element and hydraulics. The available output drops when other equipment is operating simultaneously, and decreases further at low temperatures and under high load.
Select a generator with good voltage regulation if driving a CNC/controlled machine or an electrofusion control unit. Poor regulation causes voltage fluctuations that the controller interprets as faults, aborting the weld – often mid-heating.
Never start large consumers such as compressors or hot-air blowers during welding. Instead, sequence the work to ensure a balanced load on the generator. If the machine continues to trip due to power issues, have it inspected – see service and maintenance.
A mobile power bank is a viable alternative to a generator when power is not required continuously all day: no engine noise, no exhaust fumes on site and no idle fuel consumption. Benefits, precautions and sizing are described in the section on mobile power banks below.