Steel Container Cabin

[Sidewinder]

Had a phone call today from a spark I know.

His company have contractors in wiring up a supply to a steel container which is a shower block.

Supply about 80m away, SWA sub-main.

TN-C-S/PME supply, with sticker.

Cabin has makers label which says, along the lines of "this unit must not be connected to a PME earth"

Client spark was going to do the job, so had got in 2c SWA, ended up too busy so they used contractors.

Installers ran in the SWA & a separate earth wire.

Refused to TT.

I say it must be TT'd, as its steel, and sitting on the ground, and, the manuf' says so, as does client spark.

No chance of mixed earthing systems either.

Or, am I just going nuts?

Comments please?...

 

[ProDave]

Treat it the same as a caravan, and TT it.

WHO "refused to TT it" ?

 

[Sidewinder]

The contractors install sparks 2 of them!

 

[Revved Up Sparky]

Would'nt this come under Mobile or Transportable Units in the BGB ?

In which case 717.411.4 prohibits use of PME except ,

i) Where the installation is continously under the supervision of a skilled or instructed person or ,

ii) The suitability and effectiveness of the means of earthing has been confirmed before the connection is made.

 

[kme]

I believe I know the cabin in question...................

It has to be TT - if for no other reason than to comply with mfr`s instructions.

iirc, we discussed this a few weeks back?

 

[Sidewinder]

510.3, 611.2(i) both require that you follow manuf' instructions too!

You could use 717, also it's virtually a caravan as well, though a static.

 

[Sidewinder]

We did KME, but LOTS has gone on since & I did not get the opportunity to get involved.

 

[Manator]

From the description provided then I would concur that it SHOULD be TT'd. It still amazes me that some electricians do what they think is right rather than do it right. I do hope you make them see the errors of their ways.

 

[kerching]

may I suggest you get them to sign a piece of paper stating that ' their work/installation is safe even though it contradicts BS7671 and the manufacturers instructions'

That should create a bit of sphincterus twitchus clenchus :Stir:

 

[batty]

I have just done five steel storage containers which each have a light on a pir and one socket in each connected into a consumer unit in each, I installed these electrics. I can state these are definitely extraneous as I tested the side of the container to the main terminal in the consumer units and it was around 6 ohms so each container was bonded in 10mm to the main earth terminal of the consumer units. Lets hope they don't have any problems with the job you are doing if they leave it unTTed.

 

[steptoe]

I have just done five steel storage containers which each have a light on a pir and one socket in each connected into a consumer unit in each, I installed these electrics. I can state these are definitely extraneous as I tested the side of the container to the main terminal in the consumer units and it was around 6 ohms so each container was bonded in 10mm to the main earth terminal of the consumer units. Lets hope they don't have any problems with the job you are doing if they leave it unTTed.

seriously?

:shakehead

as for the OP

manuf instructions at the very least,

everything else is just another reason.

 

[Revved Up Sparky]

I'm guessing Steps wants to know whether those MET's are connected to earth rod/s .... !

:Salute

 

[batty]

It is TNCS supply and this originally was taken to a porta cabin which is TT. This has been altered now to get supplies to the containers. Each container is protected by a 20 amp double pole RCBO and wired back to one central distribution board with a din rail meter and RCBO to supply them. I have earth bonded each container back to the earth terminal in the consumer unit in each container. I really can't see the need to TT each container separate as it TT supply any way. Am I wrong though?

 

[NozSpark]

IMHO TT earths to things like this should be local as you could get a PD between the electrical earth and the local earth

 

[batty]

The containers are no more than 6 inches apart and the first is probably 4 meters from the earth rod.