A lighting scheme uses DALI drivers, and the DALI pair runs in the same five-core cable as the 230 V supply. A colleague says the pair is SELV data and must be segregated under 528.1. Is he right?

In most drivers the DALI terminals have only basic insulation from the mains, so the pair is not SELV. It is treated as mains wiring: mains-rated cable, often in the same cable as the supply, and included when you isolate. Calling it Band I data is the tempting mistake. PELV is wrong too: in most drivers the pair has only basic insulation from the mains, so it is neither SELV nor PELV. Check the driver maker’s instructions.

Yes, as any bus cable is Band I and must be kept apart from mains

No, the pair is treated as mains wiring and included in isolation

Yes, unless the five-core cable has an earthed screen round the pair

No, because DALI is PELV, which may share any cable with the mains

You are choosing cable for a run that will carry Power over Ethernet to a ceiling access point. Which cable does Section 716 accept?

716.521.101 lists Cat 5, 6, 6A, 7, 7A, 8.1 and 8.2, or other cables defined in BS EN 50173-1. Alarm cable, flexible cord and twin-and-earth are not balanced data cabling, so they are not on the list, even though some of them could carry the current.

Six-core unscreened alarm cable

Two-core 0.75 mm² flexible cord

1.0 mm² flat twin-and-earth cable

Inside a house, a Cat 6 run has to go alongside a twin-and-earth cable that is clipped direct, with no conduit, trunking or partition. What safety separation does the On-Site Guide give?

The On-Site Guide allows 50 mm only where the mains is in its own conduit or trunking (bonded if metallic), is mineral-insulated or earthed-armoured, or a protective partition separates the cables. In other cases it is at least 150 mm, or the BS EN 50174-2 EMC figure if that is greater. The 50 mm figure is the tempting one, but none of its conditions applies here.

At least 150 mm, or the BS EN 50174-2 figure if greater

At least 50 mm, as it does for any internal data cable

None, because the twin-and-earth already has a sheath

At least 150 mm, but only if the run is longer than 4 m

Free mock exam

Installation, testing and handover — Smart Home Technology Practice

Free topic-focused mock exam: all 30 questions on Installation, testing and handover, drawn from the wider Smart Home Technology bank. 35-minute timer, 70% to pass, worked explanation on every question. Use this when you've taken the full mock once and want to drill the topics you got wrong.

Questions: 30
Time limit: 35 min
Pass mark: 70% · 21/30
Question bank: 30

Free, no sign-up. Retake as many times as you like — the questions are reshuffled, with the answer order changed.

Sample questions

01A lighting scheme uses DALI drivers, and the DALI pair runs in the same five-core cable as the 230 V supply. A colleague says the pair is SELV data and must be segregated under 528.1. Is he right?
- ANo, the pair is treated as mains wiring and included in isolation
- BYes, unless the five-core cable has an earthed screen round the pair
- CYes, as any bus cable is Band I and must be kept apart from mains
- DNo, because DALI is PELV, which may share any cable with the mains
Why: In most drivers the DALI terminals have only basic insulation from the mains, so the pair is not SELV. It is treated as mains wiring: mains-rated cable, often in the same cable as the supply, and included when you isolate. Calling it Band I data is the tempting mistake. PELV is wrong too: in most drivers the pair has only basic insulation from the mains, so it is neither SELV nor PELV. Check the driver maker’s instructions.
02You are choosing cable for a run that will carry Power over Ethernet to a ceiling access point. Which cable does Section 716 accept?
- ATwo-core 0.75 mm² flexible cord
- BSix-core unscreened alarm cable
- C1.0 mm² flat twin-and-earth cable
- DCat 6A twisted-pair data cable
Why: 716.521.101 lists Cat 5, 6, 6A, 7, 7A, 8.1 and 8.2, or other cables defined in BS EN 50173-1. Alarm cable, flexible cord and twin-and-earth are not balanced data cabling, so they are not on the list, even though some of them could carry the current.
03Inside a house, a Cat 6 run has to go alongside a twin-and-earth cable that is clipped direct, with no conduit, trunking or partition. What safety separation does the On-Site Guide give?
- AAt least 150 mm, but only if the run is longer than 4 m
- BNone, because the twin-and-earth already has a sheath
- CAt least 150 mm, or the BS EN 50174-2 figure if greater
- DAt least 50 mm, as it does for any internal data cable
Why: The On-Site Guide allows 50 mm only where the mains is in its own conduit or trunking (bonded if metallic), is mineral-insulated or earthed-armoured, or a protective partition separates the cables. In other cases it is at least 150 mm, or the BS EN 50174-2 EMC figure if that is greater. The 50 mm figure is the tempting one, but none of its conditions applies here.

Common questions

Is the Installation, testing and handover mock exam free?

Yes — 100% free, no sign-up needed. Questions are pulled at random from a substantial bank, with a worked explanation on every question after you submit.

Can I retake the mock exam?

Yes. Every attempt picks a different random selection and reshuffles the options, so each retake gives you genuinely new questions. No limit on retakes.

Does this count towards the real qualification?

No — this is independent practice material. To gain the actual qualification you need to sit the official assessment through an approved provider.