Distribution box from 32amp generator supply?

[ban-all-sheds]

Part P doesn't apply, as it's not in or shared with a dwelling, so any competent electrician can sign an EIC if he feels OK about it.

I recommend tri-rated cables for the internal ones.

 

[RF Lighting]

So it's this then: http://www.alertelectrical.com/Cons...t-3-way-IP65-Garage-Consumer-Unit-A286002.asp and swap the 6A MCB for a 16? It'll still save me £200, maybe you lot have £200 more spare than I do.

So you want to take one of the cheapest nastiest domestic CUs on the market, and use it in probably the second harshest environment for an electrical installation?

I get the feeling that your mind is made up, and regardless of whatever we say, you'll go ahead with this anyway.

Remember, this is not some little domestic DIY project. If you get this wrong by speccing cheap or incorrect materials, there could be innocent members of the public who get injured.

I know we all like to try and save the pennies, but is it really worth it when you can buy an off the shelf product which is designed for exactly this sort of installation? Think of all the time and money you will save working out what you need, where to get it from, getting it, assembling it, getting it all working, getting it tested, not to mention the piece of mind for both you and your customers.

What if you are working for a customer or if one of their guests has a bit of knowledge about electrics. Is your image as a professional company really worth risking over £200?

 

[BarryConvex]

Yet people are allowed to legally market this?
http://www.pcwb.co.uk/catalogue/item/VIDADA10?awc=2371_1247686699_7c1dcabd62ba128cbe1e5bd0cc1846cd
Where's the safety compliance in that?

Is this a better product?
http://www.screwfix.com/prods/63138...r-Units/Volex-2-Way-RCD-Garage-Consumer-Unit#

So will splitting into two 16A limited circuits not be safer and more useful than the one 32A of the Rubber Box mentioned earlier? (Which also has no weatherproof 13A sockets)

Honestly, please explain how a £250 unit with no weatherproofing is more durable in this "second harshest environment" you describe than the one I envisage making?

If it's your honest opinion that the safety measures on the CUs I've looked at are not to BS, spec, or generally an adequate quality then please continue. I just don't necessarily make the same assumption as you about off the shelf and hand crafted items. I need a little more convincing that my skills and your knowledge can't make a safe, durable unit.

As for budget, it's for me to decide if I can afford 1 day and £50 rather than £250.

And the company image is a funny one. Believe me, considering the competition, the reaction would be more like "sheeeet, you have RCDs? You really give a **** don't you?"

I'm learning a hell of a lot here, thanks.

 

[electronicsuk]

Yet people are allowed to legally market this?
http://www.pcwb.co.uk/catalogue/item/VIDADA10?awc=2371_1247686699_7c1dcabd62ba128cbe1e5bd0cc1846cd
Where's the safety compliance in that?

You're comparing two completely different things. That's a pre-assembled product that (hopefully) has been designed and tested to the relevant standards and is safe to use.

As we have been saying all along, if the cable used between the 32A commando and 13A sockets is rated to 32A then there is no problem. This wouldn't apply to anything >32A though, as BS1363 accessories are designed to be used on 32A ring circuits, therefore anything more than that and we cannot be sure that the terminals on the accessories are appropriately rated.

Is this a better product?
http://www.screwfix.com/prods/63138...Volex-2-Way-RCD-Garage-Consumer-Unit#[/QUOTE]

A little, but not by much. You should be looking at MEM, Wylex, Merlin Gerin, MK and others.

So will splitting into two 16A limited circuits not be safer and more useful than the one 32A of the Rubber Box mentioned earlier? (Which also has no weatherproof 13A sockets)

It would certainly make it easier to bring it down into 13A sockets. If you had a 32a - 2x 16A distro with fused outlets then you could (probably) then have internally fused 13A extension strips wired to 16A commando plugs without the need for ridiculously large conductors that you wouldn't be able to terminate into the extension strip.

Honestly, please explain how a £250 unit with no weatherproofing is more durable in this "second harshest environment" you describe than the one I envisage making?

Perhaps because it's made out of rubber? Also, I expect the particular unit you're looking at isn't designed for outdoor use, but rubberbox will manufacture to spec, so I'm sure they could make you something with weatherproof 13A outlets.

 

[Spark123]

Can you start by telling us what your method of fault protection (indirect contact) is going to be?

 

[BarryConvex]

That's a pre-assembled product that (hopefully) has been designed and tested to the relevant standards

Yet it has no safety cut out.
I get the issue with cable size when downsizing connectors, it must be rated for the larger connector. Also the impracticality of 32A cable into 13A terminals.

If you had a 32a - 2x 16A distro with fused outlets then you could (probably) then have internally fused 13A extension strips wired to 16A commando plugs without the need for ridiculously large conductors

I like the sound of that, although it still allows for the use of non weatherproof 13A sockets even if the 16A conns are. Although they should be self fused, as you rightly said.

I suppose one of my problems is that I don't consider this to be an 'outside' application, which is why I'm questioning the need for weatherproof sockets. All conns and possible distro are attached underneath a table top with a drip strip edge and the tent itself is a huge ex-army canvas thing. It's not as if I'm in a garden with a hose pipe, or using a £20 gazebo for that matter.

Maybe the council fellas are seeing how unlikely moisture problems are and applying BS 7909:2008 as a code of practice rather than a spec. Whereas you pros are reading it schematically (quite rightly) as not-to-spec and alarm bells are ringing.

Hmmm, I think I may phone a local distro hire place tomorrow and see what their angle is on this. They always have a van load of illegitimate looking connectors with them. [/quote]

 

[ban-all-sheds]

That's a pre-assembled product that (hopefully) has been designed and tested to the relevant standards

Yet it has no safety cut out.

Why does it need one?

Also the impracticality of 32A cable into 13A terminals.

Sockets are made to be used on 32A radials...

 

[BarryConvex]

Can you start by telling us what your method of fault protection (indirect contact) is going to be?

Not sure if that's a blatant trick question or not. I obviously don't know the sub-sections of faults like a pro. As discussed, I'm suggesting a 30mA RCD (fault protection) and 2x 16A MCBs (overcurrent protection).

Are you suggesting more is needed? Do the off-the-shelf solutions include more?

 

[BarryConvex]

Why does it need one?

Why do I need one then? I could buy this, get it PAT tested and the safety officer would go "yeah, nice PAT sticker, carry on". Brilliant.

Sockets are made to be used on 32A radials...

That was referring to trailing flex and multigang extension sockets. See the quote my comment was refering to.

 

[electronicsuk]

That's a pre-assembled product that (hopefully) has been designed and tested to the relevant standards

Yet it has no safety cut out.

Exactly what is a 'safety cut out'? If you mean that it has no MCB/RCD/fusing, then that's because there's no need. That product is designed for indoor use, for power distribution to IT equipment. The sockets, on account of not being trailing types for use on extension leads, will have terminals on the rear rated to 32A and capable of accommodating the correct size cable. The BS1362 fuse in the plug provides overcurrent protection.

I get the issue with cable size when downsizing connectors, it must be rated for the larger connector. Also the impracticality of 32A cable into 13A terminals.

Exactly. You suggested trailing socket extension leads, and these are NOT designed to be put on a ring final, therefore will not accept large enough conductors or handle 32A through the terminals at the rear.

If you had a 32a - 2x 16A distro with fused outlets then you could (probably) then have internally fused 13A extension strips wired to 16A commando plugs without the need for ridiculously large conductors

I like the sound of that, although it still allows for the use of non weatherproof 13A sockets even if the 16A conns are. Although they should be self fused, as you rightly said.

Indeed, it would not be weatherproof, but then again none of the solutions proposed so far seem to have met that requirement.

I suppose one of my problems is that I don't consider this to be an 'outside' application, which is why I'm questioning the need for weatherproof sockets. All conns and possible distro are attached underneath a table top with a drip strip edge and the tent itself is a huge ex-army canvas thing. It's not as if I'm in a garden with a hose pipe, or using a £20 gazebo for that matter.

Surely it makes sense to plan for the unexpected? What happens, for example, if a very large gust of wind manages to blow over the gazabo? The last thing you want is 13A plugs/sockets sitting in puddles of water when you're trying to find your way out of an upside down tent!

Maybe the council fellas are seeing how unlikely moisture problems are and applying BS 7909:2008 as a code of practice rather than a spec. Whereas you pros are reading it schematically (quite rightly) as not-to-spec and alarm bells are ringing.

If the council have their own set of rules then that's their prerogative, you can't possibly expect us to advise on a set of guidelines that we don't even have.

 

[Spark123]

Can you start by telling us what your method of fault protection (indirect contact) is going to be?

Not sure if that's a blatant trick question or not. I obviously don't know the sub-sections of faults like a pro. As discussed, I'm suggesting a 30mA RCD (fault protection) and 2x 16A MCBs (overcurrent protection).

Are you suggesting more is needed? Do the off-the-shelf solutions include more?

It certainly is not a trick question - the supply type is very important in determining what protective measures you are implementing. Small generators may be separate and therefore require double poled MCBs and earth free local equipotential bonding, RCDs are not much use for this type.
TN systems may still be used with single poled MCBs, I'm thinking that as high as 32A it should be TN but you'll need to stake it to ensure a good earth.

 

[JohnD]

I run a small event marquee which has recently been bumped up to a 32 amp requirement by the addition of an electric urn.

Maybe just buy a gas urn.

 

[BarryConvex]

Small generators may be separate and therefore require double poled MCBs and earth free local equipotential bonding, RCDs are not much use for this type.

Is this connected to an earlier comment about the generator possibly requiring its own specialised RCB? The quotation below is only a wiki but states a similar point. If so then it's out of my hands, that's the distro boys job. I'm starting to wonder if this whole issue is a gray area about who's responsibility this is, distro boys or mine...

One exception is the case of a TT earthing system where the earth loop impedance may be high, meaning that a ground fault might not cause sufficient current to trip an ordinary circuit breaker or fuse. In this case a special 100 mA (or greater) trip current time-delayed RCD is installed covering the whole installation and then more sensitive RCDs should be installed downstream of it for sockets and other circuits which are considered high risk.

Maybe just buy a gas urn.

That's definitely going to happen. I don't think reducing my supply to 16A completely negates my obligation and wishes for safety devices though.

If the council have their own set of rules then that's their prerogative, you can't possibly expect us to advise on a set of guidelines that we don't even have.

I don't expect you to, sorry if it's coming across that way. The guidelines I was referring to were outlined in the magazine article linked to earlier. I'm very appreciative of your knowledge of the specs that you do work with and am finding this thread very enlightening. It's also broadening my perspective of you average "safety official".

 

[Spark123]

If a generator is going to supply an ADS system then it may as well be TN-S.

If it was to be TT then you'd end up with more than one elecrode. One for the current using equipment and one to earth the source and tie the neutral down. The general mass of earth connects the two electrodes - there is no copper connection between the two.

Some people think that just because a generator has an elecrode it is a TT system - that is wrong. The electrode at the generator is the means of earthing. If the generator is earthed and the neutral point tied to it then the current using equipment and its associated protective conductors are connected directly back to the generator then it is a TN-S, the T means the source is earthed, N means there is a direct connection between exposed conductive parts and the supply system, S means the earth and neutral conductors are separate.

Unless you are authorised by the secretary of state you cant use TN-CS.