Use of RCBOs (MCB with integral RCD) for lighting rig power supplies

[Rob Bartholomew]

Has anyone any experience regarding the following isuue?

 

We have just had new Drama and Dance studios built. A nationally known stage installation company has installed the lighting rig and has specified the use of RCBOs (MCB with integral RCD) on the power supply to the dimmer racks. However, the building project company says this is not necessary because -

 

"The stage lighting system is essentially a fixed installation with changes and adjustments made by skilled or instructed persons and falls outside the scope of this requirement".

 

The stage installation company says -

 

"Whilst the stage lighting “rig” is fixed the lights are not, they are classed as portable equipment and as such must be protected by RCD devices.

Furthermore the lights will be moved by an operator “ie focused” when they are live, whether they are moved by a trained staff or not is not relevant, if there was a fault on a lantern and it was “touched” by an operator they could get an electric shock. Whilst the shock may not cause a severe injury we have to remember they are working at height and that further intensifies the risk".

 

Personally I feel we should err on the side of safety.

 

Has anyone any advice?

 

Thanks Rob

[Brian]

The building project company are wrong.

 

Your building will need a Premises Licence. Premises Licences either have explicit statements in them regarding RCDs or refer to the Yellow Book.

 

In my Premises Licence it states...

 

"Electrical circuits serving areas licensed for public entertainment shall, in addition to normal circuit protection, be equipped with sensitive earth leakage protection..." . No mnetion of nay exemptions for stage lighting circuits.

 

The Yellow Book (section F1.38) states that "RCD protection should be provided to all sockets supplying mains voltage located on stages... Sockets intended for the connection of stage lighting and controlled by dimming should be protected on the basis of one RCD to no more than 12 final sub-circuits..."

 

 

End of story really.

[back_ache]

Are the dimmers being hardwired or will they be going through a ceeform plug and socket? If you are using a socket, that could be seen as where the fixed wiring ends and the temporary begins.

 

In either case, I would err on the side of safety and go with RCBO

[Rob Bartholomew]

The dimmer racks are connected via Ceeforms

R

 

 

 

Are the dimmers being hardwired or will they be going through a ceeform plug and socket? If you are using a socket, that could be seen as where the fixed wiring ends and the temporary begins.

 

In either case, I would err on the side of safety and go with RCBO

[grumpy 2]

If it is a dance studio then you will want to use lowlevel side lights. The lanterns will then be accessable to performers. Knowing dancers they will use the booms/tanktraps as ballet bars to do there warmup. The dancers are not trained ( "changes and adjustments made by skilled or instructed persons" ). How are you going to stop the dancers touching the floor lanterns. Hence they shoud have RCBOs as the equipment is accessable to untrained persons.

[Rob Bartholomew]

All good points which I can use to support my case.

 

Please keep 'em coming

 

R

 

 

If it is a dance studio then you will want to use lowlevel side lights. The lanterns will then be accessable to performers. Knowing dancers they will use the booms/tanktraps as ballet bars to do there warmup. The dancers are not trained ( "changes and adjustments made by skilled or instructed persons" ). How are you going to stop the dancers touching the floor lanterns. Hence they shoud have RCBOs as the equipment is accessable to untrained persons.

[Brian]

... Hence they shoud have RCBOs as the equipment is accessable to untrained persons.

 

[PEDANT]

Irrelevant.

[/PEDANT]

 

Socket outlets in commercial premises, where those sockets are not used by members of the public, do not have to have RCDs feeding them (BS7671 411.3.3) The reasoning behind this is that commercial premises are covered by the Electricity at Work Regulations and these require a safe system of work which means someone is in control of activities. EWR always requires workplace equipment to be maintained and safe. Because of these two factors there is no additional protection required.

 

The dancer scenario is no different to a cleaner using a floor scrubber in the reception area. The scrubber will be maintained and tested and the cleaner instructed in checking the flex and plug for damage before use. Therefore the wall sockets do not need RCDs.

 

 

It is 411.3.3 which the building project company is relying on. Their wording reflect this.

 

 

However, what they are missing is that the designer must consider any special circumstances which might give rise to an increased risk.

 

Because access whilst focussing will always involve working at heights and working with energised equipment the designer must consider the risk of electric shock at height. It is for the reason that that RCDs should be fitted to dimmers.