Portable Cabins

[Bacon]

Have got 6 PIR's to carry out for Army on these they are TT when deployed feed via Geny,

The main switch is the old ELCB with earth test buttons on them then to dist board 100A then 3 rcd's feeding Lights 6A Smoke Alarm 6A and Socket 16A

would I be wise to point out that there needs to be an RCD for main isolation under a code 1.

Absence of adequate protective devices (e.g. residual current devices for TT installations),

Have already found numerous faults with the installation no earth on any of the light switches and no earth from socket to back box all are metal-clad,no labels on board identifying circuits.

Thanks

 

[Apache]

1. Don't the army have their own electrical standards?

2. Assuming the metal frame was bonded to earth could you rely on it to protect the switch under fault conditions?

 

[steptoe]

are you sure it is TT?

sounds dubious to me.

plus as apache states, the MOD have their own rules.

but Im still not convinced these are TT, they may in fact be earth free, needs some more info I feel.

 

[Bacon]

They are TT because i have about 3 earth rods for each one and they are either ground dumped or on the back of a wagon when in use.

They have to comply with the current regs,as on previous cabins they were all brought up to 17th edition standards where the ELCB's were removed and isolator's fitted and RCD was fitted to main board for the incomer from isolator and rcbo to lighting circuits.

Wiring is PVC/PVC in galv conduit all internal walls are hard board

They have to feeds into it that can be used either mains feed when in a workshop and a geny feed when on deployment.

I'll get some photos later.

 

[septiclecky]

Patch/Steps you have both lost me as where does the poster mention Army or MOD?

 

[PC Electrics]

Patch/Steps you have both lost me as where does the poster mention Army or MOD?

1st post, 1st sentence, 9th word = army

 

[Badger]

1st post, 1st sentence, 9th word = army

:Salute :Salute:^O:Applaud:run

 

[PC Electrics]

Have got 6 PIR's to carry out for Army on these they are TT when deployed feed via Geny,The main switch is the old ELCB with earth test buttons on them then to dist board 100A then 3 rcd's feeding Lights 6A Smoke Alarm 6A and Socket 16A

would I be wise to point out that there needs to be an RCD for main isolation under a code 1. (1)

Absence of adequate protective devices (e.g. residual current devices for TT installations),

Have already found numerous faults with the installation no earth on any of the light switches (2) and no earth from socket to back box (3) all are metal-clad,no labels on board identifying circuits (4).

Thanks

1. A 100mA type S to protect the distribution circuit as you already have RCDs protecting the circuits (though you don't say which type). Unless the dc is buried <50mm and not armoured, then you'll need 30mA and lose the discrimination and seperation of circuits, so might be best to re-cable the dc on the surface so you can use s type.

2. In a later post you mention galv conduit - you sure this isn't providing the cpc? have you checked its continuity for this purpose?

3. not required providing one of the lugs are fixed.

4. fair enough, but easy to rectify with a pen and some labels (or for a more professional finish, your labeler if you have one)

 

[septiclecky]

It was early headbang

 

[Bacon]

Information i was intially given said TT but on further investigation they are not my fault for confusion.

The conduit does have a good earth back to the to the board and is ok but i would still like the earth brought into the switches.

 

[Andy™]

if the genny is built into the container, then it may well be TNS. the rod is simply there to connect star point to ground

 

[PC Electrics]

Information i was intially given said TT but on further investigation they are not my fault for confusion.The conduit does have a good earth back to the to the board and is ok but i would still like the earth brought into the switches.

Maybe you would, but I thought this was a PIR. In which case, since using the conduit as cpc is perfectly acceptable to BS7671, you cannot mark it as a non conformance nor insist a seperate cpc is installed. You can suggest it to your client, but they are entitled to accept or reject your suggestion.

 

[Apache]

i would still like the earth brought into the switches.

What material are the switches made from? Is there continuity from the conduit to the back box or the switch front if they are metal?

 

[Bacon]

Sockets and switches are metal clad and i do have continuity from them via the conduit.

 

[Apache]

Sockets and switches are metal clad and i do have continuity from them via the conduit.

Then what's the issue?

 

[Bacon]

The issue is from my point of view you should allways have an earthed connection on any metalic socket or switch.

And also if the first fixed point of the conduit that is connected to the outer metal frame became detached then you have lost the protection to the switches as there is no bonding in side as it's hardboard walls.

 

[Apache]

The issue is from my point of view you should allways have an earthed connection on any metalic socket or switch.

You mean an earth connection between the backbox and faceplate?

And also if the first fixed point of the conduit that is connected to the outer metal frame became detached then you have lost the protection to the switches as there is no bonding in side as it's hardboard walls.

IF your earth rod becomes disconnected (and there are no other bonded services) you lose the earth.

(see http://www.talk.electricianforum.co.uk/showthread.php?p=64070#post64070 - it's still like that!)

IF a helicopter lands on said cabin you won't care about the electrics.

The conduit will have a much greater surface area than a wire and be less susceptible to damage or been pulled out of a fitting.

 

[steptoe]

Information i was intially given said TT but on further investigation they are not my fault for confusion.The conduit does have a good earth back to the to the board and is ok but i would still like the earth brought into the switches.

so what earthing system is it.?

The issue is from my point of view you should allways have an earthed connection on any metalic socket or switch.And also if the first fixed point of the conduit that is connected to the outer metal frame became detached then you have lost the protection to the switches as there is no bonding in side as it's hardboard walls.

or the earthing conductor in a house became detached........

do you see where Im coming from.?

if it is earthed its earthed,

where would you stop,?

maybe we should have a fly lead to the metal window frames, and drill a hole in the sink for a lug too, oh, and lets lug all the radiators too,

but what about the metal door handles.?

 

[Badger]

so what earthing system is it.?or the earthing conductor in a house became detached........

do you see where Im coming from.?

if it is earthed its earthed,

where would you stop,?

maybe we should have a fly lead to the metal window frames, and drill a hole in the sink for a lug too, oh, and lets lug all the radiators too,

but what about the metal door handles.?

:^O :^O:^OROTFWL:Applaud:Applaud:Applaud:run

 

[Lurch]

The issue is from my point of view you should allways have an earthed connection on any metalic socket or switch.

There is.

I have wired schools and factories with galv conduit used as CPC's, I've also done PIR's on plenty. TBH, a cabin would be better than some of the other larger installs with conduit based CPC's as there's no buried joints and it's all short runs.

And also if the first fixed point of the conduit that is connected to the outer metal frame became detached then you have lost the protection to the switches as there is no bonding in side as it's hardboard walls.

And?

You can;t mark it down unless you can find a regulation to back it up. There's plenty to back up the use of conduit as a CPC, but none to condemn it, just to save you the hassle of looking. Basically, cowboys convince customers to have unnecessary work done.