Burying Cables

[daveharding111]

we are looking to bury a few cables at our little festi this year, but our sparky is very uncomfortable with it basically he is telling us we can't do it despite it being a standard practice at every festival I've worked at. so my question is, how does burying cables (e.g. stage to FOH) stand up against BS7909, is there a little piece of legislation that allows this practice that I can point him to? or is it an unacceptable practice that everyone does anyway? personally I find it hard to believe that such a common practice would be breaking regs.

Thanks

Dave

[Simon Lewis]

Dave,

 

BS7671 stipulates various conditions for burying power cables (prepared ground, sufficient depth [more than 500mm], physical protection, cable markers or covers etc.). Given that many festivals simply 'slit trench' the cable in, it may be that your sparky is not comfortable deviating from these?

 

This IET leaflet is a little out of date (some revisions have taken place since 2009) but does provide some helpful information...

 

Simon

[Dave m]

Added cost, and dependant on landowners permissions, but would burying a pipe/duct and drawstring be an option? More initially, but less hassle afterwards if it is a repeat performance.

Hardly the same but I ran an armoured mains cable to my shed, and 2 blue water pipes .Now I wish that I had used a duct as hand digging and fixing where it crossed the path was a pain that I don't wish to do again I blagged a strip of "mains cable below" plastic tape from our electrics dept in case somebody ever digs down

Would plastic drainage pipe be ok?

[Brian]

Would plastic drainage pipe be ok?

 

You can buy proper 'duct' pipe for not much money. It's the stuff that's corrugated on the outside but with a smooth inner wall.

[itiba]

Dave,

 

BS7671 stipulates various conditions for burying power cables (prepared ground, sufficient depth [more than 500mm], physical protection, cable markers or covers etc.). Given that many festivals simply 'slit trench' the cable in, it may be that your sparky is not comfortable deviating from these?

 

This IET leaflet is a little out of date (some revisions have taken place since 2009) but does provide some helpful information...

 

Simon

 

It might be worth considering the intent behind that regulation and any assumptions made - an assumption that such a cable that might be in place for many decades would certainly require protection as described. Provided that some relatively easy to implement control measures are introduced - for example signage and co-ordination with other users on the site to make sure do one will be digging or mowing etc I would consider it appropriate for a 'slit trench' to be used on a temporary basis. Such a decision would ultimately be up to the 'designer' of your electrical installation who should record such a deviation (and control measures in place) on the certificate.

 

Alternatively you can put down 100m of cable ramp but from past experience this isn't cheap or fun.

[Simon Lewis]

We in the industry know and understand this... my point was that many sparkies work only to the constraints of fixed installs and 7671 - so have an aversion to deviations from this.

 

When I did my 7671 course a few years back, all the electricians taking the course could quote chapter and verse of the regs, but didn't know about temporary supplies, generator earthing or the load characteristics of the equipment we use. I mentioned BS7909 to the instructor taking the C&G course. He had not heard of it.

This is said not to denigrate the average electrician... we just do things outside their normal sphere of work....