15 Facts you didn't know about Neon - Part 5

Every seen a neon tube come to life ? One of the most amazing things about when a tube is first made is the way in which it comes to life, the tube starts of bright at either end and dim in the middle, the light slowly works its way through the tube towards the centre until it has a bright even illumination right the way through. It is great to see.

This one is a bit of a longer one but explains some of the more intricate information about a neon sign installation in the UK.

Can Neon be used outside?

Yes neon can be used outside. Externally suitable transformers are IP 44 rated, but must be mounted correctly, some small electronic transformers are IP65 rated and can also be used outside except when over a certain voltage. Neon glass is perfectly fine in the Great British weather.

When does a Neon sign need to have a Fire-fighter's switch installed?

Short Answer:-

Any permanent, non-portable, high voltage neon sign over 100w (e.g max 8kv/18ma), will require a fire-fighters switch or connecting to a fire circuit.

Full Answer:-

Fire-fighter switches are not always required. When considering the requirement, we need to look at the relevant regulations, and these are found in the IET Electrical Regulations.

The IET Electrical Regulations 18th Edition States:-

537.4.2 - A Fire-fighter's switch shall be provided in the low voltage circuit supplying:

1.      Outdoor Lighting installations operating at a voltage exceeding low voltage, and

2.      Indoor discharge lighting installations operating at a voltage exceeding low voltage.

For the purposes of this regulation, an installation in a covered market, arcade or shopping mall is considered to be an outdoor installation. A temporary installation in a permanent building used for exhibitions is considered not to be an exterior installation.

This requirement does not apply to a portable discharge luminaire or to a sign of a rating not exceeding 100w and fed from a readily accessible socket-outlet.

When considering this regulation we need to understand the definition of portable and the definition of what constitutes low voltage.

The definition of portable as outlined in the British Standard BS 559:2009 Design & Construction of Signs is:-

3.1.5 Portable Sign - Small self contained sign which is supplied as a complete unit and is intended to be placed in position and, if illuminated, connected to a mains supply, usually by an unskilled person.

Note: - A Portable Illuminated sign is usually supplied with an integral lead for connecting to the mains supply and this often includes a mains plug.

The definition of low voltage as outlined in the British Standard BS 559:2009:-

3.3.1 Low Voltage - nominal voltage normally exceeding extra-low voltage but not exceeding 1,000 V a.c. or 1,500V d.c between conductors, or 600V a.c. or 900V d.c. between conductors and earth.

So from the above we can say the following:-

·        A "portable" luminaire (e.g. an art piece) can be of any wattage or voltage and does not require a fire-fighter's switch.

·        A sign powered by multiple low voltage transformers (990v) does not require a fire-fighter's switch.

·        A sign of less than 100w fed from a readily accessible socket does not require a fire-fighter's switch.

·        A non-portable sign over 100w requires a fire-fighter's switch.

So what does 100w allow us to have? This is dependent on the amount of mA (Milliamps) being passed through the tubes and the voltage required for the installation. 

When working out wattage there are two methods, one is the apparent power (expressed as Volt Ampere) and the other is the Real power (Watts).

Volt Ampere is worked out with the following equation from ohms Law -

P(Watts) = V(Volts) x I(Amps)

However this is not the Real power in watts that is obtained, it is actually Volt-Ampere's which is not the same thing.  

Real power is worked out by multiplying VA (Volta-ampere) x Power Factor (cosφ) which for Wire wound transformers is 0.5, this results in a much lower wattage. With this in mind anything up to and including the following transformers should be able to be used, as their Real power is less than 100w when running:-

Wire Wound Transformer:-

6kV 25mA running at 95 watts.

8kV 18mA running at 95 watts.

Electronic transformer:-

8kV/ 20mA running at around 95% of full capacity. As Less load uses less power.

Installations should be individually checked when running as cabling and other factors can affect the efficiency.

When a fire-fighter's switch is required the regulations state:-

537.6.2 - Every exterior installation covered by regulation 537.6.1 in each single premises shall wherever practicable be controlled by a single fire-fighter's switch. Similarly, every internal installation covered by Regulation 537.6.1 in each single premises shall be controlled by a single fire-fighter's switch independent of the switch for any exterior installation.

537.6.3 - Every fire-fighters switch provided for compliance with Regulation 537.6.1 shall comply with all the relevant requirements of the following items (i) to (iv) and any requirements of the local authority:

(i).  For an exterior installation, the switch shall be outside the building and adjacent to the equipment, or alternatively a notice indicating the position of the switch shall be placed adjacent to the equipment and a notice shall be fixed near the switch so as to render it clearly distinguishable.

(ii).  For an interior installation, the switch shall be in the main entrance to the building or in another position to be agreed with the local fire authority.

(iii). The switch shall be placed in a conspicuous position, reasonably accessible to fire-fighters and, except where otherwise agreed with the local fire authority, at not more than 2.75m from the ground or the standing beneath the switch.

(iv). Where more than one switch is installed on any one building, each switch shall be clearly marked to indicate the installation or part of the installation which it controls.

So in short internal and external neon signs should have separate fire-fighter switches, these should be ideally placed next to the sign that it controls or in the main entrance of the building, if not then a sign saying where the switch is should be provided along with a label for the switch. The switch should be no higher than 2.75m from the floor. Due to the age of the regulation and the fact is has not been updated for quite some time, It is also it is possible to connect into an alarm circuit that switches of when a fire is detected, this should be confirmed as acceptable by the local fire authority however.

The reason fire-fighter switches are required is that when spraying water over high-voltage installations it allows the voltage to travel up the water being sprayed, it is a safety feature for the fire-fighters, should they ever be required. It is not the fact that a neon sign is more likely to cause a fire, as when installed correctly a neon sign is just as safe as any other electrical installation or appliance.

Keep an eye out for the next article where we will answer a couple more questions.

For more information about neon visit our showcase pages or visit our website https://www.a1designs.co.uk

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