Questions we are asked at enquiry stage.

Contestable works may be delivered by an accredited ICP and typically cover the HV cable route from the point of connection, the point of connection substation, metering and protection to DNO specification, earthing, and everything on the customer side of the ownership boundary. Non-contestable works — the connection to the existing network, any reinforcement and the final adoption inspection — remain with the DNO.

CrestWatt provides the design, project management and DNO liaison for contestable connection works. The accredited installation is delivered by NERS registered partners working under CrestWatt supervision and within CrestWatt’s test and records regime.

The relevant DNO’s ICP approval policy and technical specifications, plus ENA EREC G99 for generation connections, ENA EREC G81 for design and planning, ENA TS 41-24 and BS EN 50522 for substation earthing, BS 7671 and the Distribution Code.

On a generation or storage project the connection sits on the critical path. Where the ICP and the commissioning contractor are the same organisation, the energisation sequence, protection settings coordination and DNO witness schedule sit inside one programme instead of across a contract boundary.

DC crimping and MC4 connector assembly at string level; LV terminations at inverter, transformer station and LVAC distribution; 11 kV and 33 kV heat shrink, cold shrink and separable connector terminations; and 66 kV and 132 kV outdoor sealing ends, GIS plug-ins and transformer bushing terminations.

Insulation resistance, VLF withstand at 0.1 Hz to IEEE 400.2, DC sheath integrity testing to IEC 60229, tan delta and partial discharge where specified, phasing and phase rotation, and TDR for fault location and length verification. Pre-termination and post-termination results are recorded separately.

Yes. Fusion splicing and pigtail termination, patch panel and splice enclosure population to the plant splicing plan, OTDR and bidirectional insertion loss testing to IEC 61280-4-1 with trace files delivered, and CAT5e to CAT7 certification to ISO/IEC 11801 and EN 50173.

Shielded twisted pair termination with daisy-chain topology verification, 120 Ω line termination and bias resistor checks, and shield earthing at one point only. Device addressing and baud rate are verified against the plant register map, and communications are proved end to end from the field device to the SCADA server.

Every string is tested for continuity of protective earthing and equipotential bonding, polarity, open-circuit voltage and short-circuit current corrected for irradiance and temperature, and insulation resistance of the DC circuits, together with a functional test of switchgear, isolation and monitoring.

Category 1 tests are applied to every string as the baseline commissioning set. Category 2 tests — IV curve tracing against the expected curve, and infrared thermographic survey of modules, connectors and combiner boxes under load — are carried out where the client or owner’s engineer specifies them.

Yes. Transformer pre-energisation checks, HV cable testing, switchgear contact resistance and timing, earthing measurements, and protection commissioning by secondary injection, primary injection for CT ratio and polarity, CT magnetisation and scheme stability testing, with DNO and owner’s engineer witness.

Records are compiled continuously against the client’s FAC checklist as the work proceeds, with instrument calibration certificates attached and a live snag register tracked to closure, rather than assembled after completion.

Electrical design and equipment specification; supply of 33 kV and 66 kV switchgear, transformers, circuit breakers and auxiliary systems; 110 V DC battery and charger systems; LVAC boards to IEC 61439; HV cable and accessories; installation supervision, jointing and termination; earthing; and testing through to DNO witness and energisation.

Yes. 33 kV XLPE to IEC 60502-2 and 66 kV XLPE to IEC 60840 are sourced through vetted manufacturers, with freight, customs, duty and inspection managed by CrestWatt. Cable has been supplied into the UK from an accredited overseas manufacturer with origin documentation handled in-house.

Yes. Where switchgear, relays or panels are client-supplied, CrestWatt takes delivery, verifies against the schedule, installs and commissions, and keeps a clear record of supply responsibility for each item.

Relays are supplied through authorised UK distribution to the client relay schedule — ABB Relion, Siemens SIPROTEC, GE Multilin, Schneider Easergy MiCOM and others to specification — together with CTs and VTs verified for ratio, class and burden.

Both. Transformer protection cubicles, line differential wall boxes, CT and CVT marshalling kiosks and control panels are designed, manufactured, wired, ferruled and factory acceptance tested, then commissioned by the same engineers on site.

SCD engineering, GOOSE and MMS configuration and substation network verification, followed by settings application, secondary and primary injection, scheme stability and functional testing, and site acceptance with DNO witness.

Field inspection of earthing, DC and AC cabling, inverters, LV distribution and transformer stations against drawings, specification and OEM requirements; witness of subcontractor tests; structured digital records on standard checklists completed on the day; daily defect reporting; and weekly progress and quality reporting against programme.

No. Supervisors inspect, witness and record. They do not direct the subcontractor’s workforce and do not carry out HV switching unless separately contracted and authorised. That separation is deliberate — it preserves the independence of the record.

On a monthly all-inclusive rate covering engineer time, accommodation, travel and expenses, pro rata for partial months. Typical engagements run eight to sixteen weeks through installation and commissioning.

Single line diagrams and cable sizing to BS 7671 and IEC 60287, PV electrical design including string configuration and DC cable schedules, earthing design to ENA TS 41-24 and BS EN 50522, protection studies and settings, and grid studies covering load flow, fault level, G99 compliance, harmonics and reactive capability.

Design and study work is scoped and quoted at a fixed price, with a stated delivery date.

Yes. Earthing design and assessment includes brownfield sites with existing buried earthing systems and soil resistivity survey — for example a 57 MW battery storage site on a former DNO compound, assessed around a live existing buried earthing system.

HV switchgear inspection and contact resistance, transformer inspection, oil sampling and protection device testing, protection relay re-verification against the current relay schedule, thermographic survey under load, earthing continuity and electrode resistance re-testing, LV periodic inspection to BS 7671, sample DC re-testing and communications verification.

Yes. CrestWatt maintains the systems it commissions and takes on operational plant built by others, working from the asset register and the existing O&M schedule.

Yes. HV cable fault location by TDR and thumper with excavation coordination, joint repair and re-testing; DC string fault finding and connector replacement; protection and control fault diagnosis and re-commissioning; and fibre fault location, re-splicing and re-certification.

Fixed-term PPM contracts with defined visit schedules and reporting, call-off corrective maintenance, and combined commissioning plus first-year O&M for new plants.