Temporary building supplies again

[cliffed]

just wondering how you guys,install temp electrics to portacabins
Seen a lot of installs on sites & at schools where I don’t think it’s correct.
Mainly earthing,& earthing conductors,or am I being over cautious,cheers.

 

[The_apprentice2.0]

I don't do a lot of it personally, but there is a standard for temp supplies, have a look at BS7909 think its tailored more to events etc but might be some help

 

[cliffed]

I don't do a lot of it personally, but there is a standard for temp supplies, have a look at BS7909 think its tailored more to events etc but might be some help

Ok

 

[Nigel]

As per Section 717 of BS 7671:2018.

 

[cliffed]

As per Section 717 of BS 7671:2018.

Agree,but I haven’t seen that being done on sites

 

[Deleted member 26818]

A lot of Portacabins seem to come pre-wired with commando sockets to link them together.

 

[cliffed]

A lot of Portacabins seem to come pre-wired with commando sockets to link them together.

Yea,more intrigued by the supply & Main bonding to it

 

[driverman]

I'm under the impression that temp supplies have to be TT earthing.
DNO's usually insist on TT earthing for temp supplies. They will not provide PME for temp supplies.
Even if Perm supply, aren't porta cabins classed as temp building as they are movable?

 

[cliffed]

I'm under the impression that temp supplies have to be TT earthing.
DNO's usually insist on TT earthing for temp supplies. They will not provide PME for temp supplies.
Even if Perm supply, aren't porta cabins classed as temp building as they are movable?

Thanks,seen so many not tt,& agree Pme should not be used.

 

[Nigel]

Agree,but I haven’t seen that being done on sites

I agree. We test a lot of steel shipping containers and they are almost never done correctly. Usually connected to a PME earth is the issue.

 

[Nigel]

A lot of Portacabins seem to come pre-wired with commando sockets to link them together.

Need PAT testing then.

 

[Deleted member 9648]

TT is not always required. TNS is acceptable. A TNCS supply to a transportable unit can be used where the installation is under the continual supervision of a skilled or instructed person. This may be the case in the units you have observed not on a TT

 

[Nigel]

I'm under the impression that temp supplies have to be TT earthing.
DNO's usually insist on TT earthing for temp supplies. They will not provide PME for temp supplies.
Even if Perm supply, aren't porta cabins classed as temp building as they are movable?

Any transportable unit will need an earth electrode installed unless it is under the supervision of 'skilled or instructed person(s)' in which case the PME can be used.

Construction sites also need to comply with Section 704 as well as 717.

 

[Deleted member 9648]

Any transportable unit will need an earth electrode installed unless it is under the supervision of 'skilled or instructed person(s)' in which case the PME can be used.

Construction sites also need to comply with Section 704 as well as 717.

A transportable unit connected to a TNS earth will not need an earth electrode or to be under supervision.

 

[Nigel]

A transportable unit connected to a TNS earth will not need an earth electrode or to be under supervision.

I know. Thanks for that.

 

[cliffed]

I agree. We test a lot of steel shipping containers and they are almost never done correctly. Usually connected to a PME earth is the issue.

Frightening

 

[cliffed]

A transportable unit connected to a TNS earth will not need an earth electrode or to be under supervision.

Yea,agree

 

[cliffed]

Any transportable unit will need an earth electrode installed unless it is under the supervision of 'skilled or instructed person(s)' in which case the PME can be used.

Construction sites also need to comply with Section 704 as well as 717.

The only thing would be if it would be realistic,especially Main Earth bonding,concerning the size of the neutral on a tncs

 

[michaelw6]

I know this is an old topic but I have a container to install on a farm. I'm also wondering what UV protected flex you peeps use? as this container is going to be portable it's a small cabin with commando socket to socket so I need to make up a flying lead. In the case above would it not be to test and see if it passes the disconnection times etc and it would be suitable?

 

[littlespark]

16A commando?

I used 2.5mm artic blue flex when wiring up static caravans.
Oversized possibly where 1.5 would do, but the thicker sheath did offer a little more protection, and just “looked” better.

 

[michaelw6]

sorry 32a commando 4.mm cable

 

[michaelw6]

hi tuf is not classed as flexible. flex does not go big enough, xlpe I don't think is a flexible cable either.

 

[loz2754]

H07RNF is tough, flexible, available in larger sizes, UV resistant, oil resistant. It's used in factories to connect up machines.

 

[michaelw6]

rubber cable im not sure of suppose it will last.

 

[michaelw6]

just looking up h07rnf looks like for 32a ill need a 6mm 3c but there is also (H)07RC4N8-F which offers more protection or am i going OTT for a flexible lead?

 

[loz2754]

Section 717 mobile or transportable units -
717.52 Wiring systems
717.52.1 Where the supply to the unit is by means of a plug and socket outlet, flexible cables in accordance with H07RN-F (BS EN 50525-2-21), or cables of equivalent design, shall be used for connecting the unit to the supply.

 

[michaelw6]

Section 717 mobile or transportable units -
717.52 Wiring systems
717.52.1 Where the supply to the unit is by means of a plug and socket outlet, flexible cables in accordance with H07RN-F (BS EN 50525-2-21), or cables of equivalent design, shall be used for connecting the unit to the supply.

Oh, thank you for spending the time to find that for me. so I have a get out of jail free card if I use the cable and they damage it. I'm usually always overly cautious with these things and thinking what if !!

 

[loz2754]

Oh, thank you for spending the time to find that for me. so I have a get out of jail free card if I use the cable and they damage it. I'm usually always overly cautious with these things and thinking what if !!

You're welcome

 

[pc1966]

I have a get out of jail free card if I use the cable and they damage it.

Really H07RN-F is pretty tough, if you need more intrinsic protection then it is really SWA and that is not suited for anything that moves more than very occasionally.

Keeping the flex out of harm's way is the best plan, so attached to tray or in some duct, maybe an overhead hawser if clearance for vehicles, etc, allows it, etc, if you can. However, many temporary sites have nothing to helps with that and are quite brutal in how they treat cables