Running power safely from gen set

[Emvee]

Hi new here and looking for some advice please!

I have a small holding and I want to run some power to some of the buildings - these are very rudimentary wooden structures and my plan is to fix up some 13A sockets and run some lights/power tools from them, as opposed to running an extension lead across the yard which is obviously not ideal!

I am using a Lister Petter AD1 gen set and I am planning to run the feed from this into a small consumer unit and then into plastic trunking which I have already installed underground to my power outlets.

My main question is regarding how an RCD would work with this set up, and whether I would need to put in a separate earth rod or would the generator body provide adequate earthing?

Also should I use SWA or 2.5mm twin and earth or would a combination of the two be okay, and if the latter how do I join it?

As this is on private land and not subject to buillding regs I don't need to worry about Part P compliance but I do want it to be as safe as possible.

Any advice would be greatly appreciated

All best

Emvee

 

[stillp]

As this is on private land and not subject to buillding regs I don't need to worry about Part P compliance

Whatever gives you that idea?

 

[ricicle]

Please seek the services of an electrician who understands generator installation before you install something which will be potentially dangerous for persons, livestock or buildings.

 

[davelx]

As this is on private land and not subject to buillding regs I don't need to worry about Part P compliance

Whatever gives you that idea?

The fact that this installation is not associated with "dwelling houses or flats" perhaps? Which means it falls outside the scope of part P.

Arguably it could be classed as a place of work, with all that that implies.

 

[Emvee]

I was rather hoping to do it myself (that's why I posted this on a DIY forum!)

Is it really that dangerous to connect a generator up to a fixed 13A socket via a domestic consumer unit? Could you perhaps give me some idea why you are so adamant that I need a qualified sparks to do this?

I don't think part P applies where I am not connected to the grid and on my own land and not employing anybody, unless I am very much mistaken

 

[ban-all-sheds]

http://electrical.theiet.org/wiring-matters/39/portable-generators.cfm?type=pdf

 

[flameport]

Is it really that dangerous to connect a generator up to a fixed 13A socket via a domestic consumer unit?

Yes. If installed incorrectly, it's very easy to kill yourself and other people/animals in the vicinity.

Could you perhaps give me some idea why you are so adamant that I need a qualified sparks to do this?

Your initial questions indicate a total lack of understanding, and you have already made several blunders.

Plastic trunking is not suitable for use underground.
T&E is not suitable for use outdoors, underground, where it is likely to be damaged or exposed to sunlight .
SWA could be used, but only if installed correctly, something which seems rather unlikely given you don't know how to connect it to other cables.
The 'generator body' won't provide earthing for anything - how could it?.
RCD's don't work unless the supply is properly referenced to earth.
An RCD is not a substitute for using the correct materials and installing them properly.

Electricity doesn't care about part P or building regulations or private land - it will stilll kill you just as quickly.

 

[Emvee]

http://electrical.theiet.org/wiring-matters/39/portable-generators.cfm?type=pdf

Thanks that's really useful

 

[Emvee]

If installed incorrectly, it's very easy to kill yourself and other people/animals in the vicinity.

Which is precisely why I came here asking for some advice (which some people seem to get and others don't).

Your initial questions indicate a total lack of understanding, and you have already made several blunders.

The reason I posted this question is to get some advice regarding the safe installation of this equipment, not to be patronised and bullied by a pedantic berk like you, but thanks for the constructive criticism (not).

To address your points

Plastic trunking is not suitable for use underground.

I am using a generator not a constant supply of electricity so I'm not going to go digging holes and cutting into cables when I know that the cables are live am I?

T&E is not suitable for use outdoors, underground, where it is likely to be damaged or exposed to sunlight

How can it be exposed to sunlight when it's buried? I am going to make sure that the cable is adequately protected - its not rocket science.

SWA could be used, but only if installed correctly, something which seems rather unlikely given you don't know how to connect it to other cables.

Perhaps someone with a more constructive attitude could explain how it's done, or point me in the right direction for that information

The 'generator body' won't provide earthing for anything - how could it?.

From my (admittedly limited) understanding I thought that some generators have a floating earth system which is "a form of electrical separation, where basic protection is provided by basic insulation of live parts and fault protection is provided by simple separation of the separated circuit from other circuits and from Earth". If that is incorrect perhaps you could explain why, rather than try to shoot me down in flames

RCD's don't work unless the supply is properly referenced to earth.

This we know - so how do you 'properly reference the circuit to earth'?

An RCD is not a substitute for using the correct materials and installing them properly.

This we know

Electricity doesn't care about part P or building regulations or private land - it will stilll kill you just as quickly.

Which is precisely why I am here asking for some help. If you have nothing constructive to say why don't you just keep quiet?

 

[ban-all-sheds]

Your initial questions indicate a total lack of understanding, and you have already made several blunders.

The reason I posted this question is to get some advice regarding the safe installation of this equipment, not to be patronised and bullied by a pedantic berk like you, but thanks for the constructive criticism (not).

The point is you can't do a job like this just by asking whatever questions you think you need answering.

What if you miss something important because you have no idea it exists, and therefore no idea that you don't know it, and therefore don't ask?

Plus your attitude stinks. You seem to regard the fact that the Building Regulations don't apply as carte-blanche to put in any lash up you like as long as you think it will be OK. You proposed some installation techniques which you were told were unacceptable, and then despite your claim that you have come here for advice proceeded to dismiss that advice and make it quite clear that you were still going to do what you had already decided to do.

Go away.

 

[ericmark]

Generators are a problem and forgetting the regulations I will try to explain.

What we want is to prevent any electricity from travelling through an animal be that on 4 legs or human. 4 legs do present more of a problem but really there are two ways to do this.

1) Ensure nothing between the supply and appliance is connected to any metal work or earth.

This is how our shaver socket works and using a generator to power a single item is similar although since it may not be powering Class II equipment not quite the same.

2) Ensure should a fault happen then the supply will automatically disconnect.

This is used when we have multiply items from the same supply.

To do this we use an earth system and returning to regulations for a minute with 4 leg animals this often needs to be a metal grid laid under the premises during it's build.

But as far as DIY goes the big problem is the testing. As an electrician I have not got the meters required to test an earth without reference to the DNO's earth. It needs test prods to be put in the ground and moved with at least 3 readings to measure the earth where there is no boards earth to compare it with. I would as an electrician need to hire the equipment even then it's not easy to use.

I have been an electrician for 40 years and for first 20 I never needed to measure an earth rod with this complex equipment. Then on one job I spend 6 months doing very little else. So even with electricians you may find it hard to find one trained in how to use this equipment. Likely they will have test equipment in one had and Book 3 in the other to work out how to use it.

Even I would need to brush up on it's use as it's so rare one needs to use it.

Added to this is the generator it's self. We want one output leg to be earthed and we call that neutral. However many generators don't have one leg earthed but earth some where between to two legs. Again some careful testing is required.

I would not say this is a DIY job.

 

[plugwash]

Added to this is the generator it's self. We want one output leg to be earthed and we call that neutral. However many generators don't have one leg earthed but earth some where between to two legs. Again some careful testing is required.

Afaict generators come into three categories.

1: those that have the earth connected to neutral.
2: those that do not have the earth connected to the output at all.
3: those that are earthed somewhere between the two legs

Number 1 is clearly the simplest case.
Number 2 is trivially converterd to number 1
Number 3 is practially speaking not that different from number 1 as long as you have double pole RCD protection (DO NOT use single pole RCBOs for RCD protection in this case) since the RCD will disconnect a fault from either leg to ether.

But I agree with ericmark the biggest problem is installing and testing your earth rod. Earth rods REALLY need to be testied (this is NOT merely a CYA test, the resistance of an earth rod can be rather unpredicatable).

And as others have said if animals are involved you need to be extra careful. Four legged animals are much more easilly killed by bad earthing setups than people are.

 

[JohnW2]

But I agree with ericmark the biggest problem is installing and testing your earth rod. Earth rods REALLY need to be testied (this is NOT merely a CYA test, the resistance of an earth rod can be rather unpredicatable).

I must be missing something, because I have always had difficulty in understanding a lot of what I read and hear about generator supplies, so I'd be grateful for some education.

Consider the simple situation in which a generator is to be used only for the local supply (say, to outbuildings) with no interaction with any mains-supplied installation. Also, in the first instance, assume that there is no earthing (i.e. no earth rod).

If the L&N outputs of the generator feed all the loads via an RCD and all loads are supplied with a CPC connected directly to the generator's neutral (not via RCD), then the RCD will operate in response to any L-CPC fault and (if the circuit is loaded) probably any N-CPC fault. If the generator (and circuit) are actually 'insulated' from earth (i.e. the whole supply is floating) then there is theoretically no risk to anyone who touches an L conductor, even if the person is in contact with true earth. As always, there is no protection for a person who touches both L&N, regardless of whether or not they are earthed.

Now introduce an unintentional (genny standing on soil, and its N connected to frame) or intentional (earth rod) connection from the generator's N to true earth. What is now different? The RCD will still operate in response to L-CPC and (usually) N-CPC faults. Unless the earth rod had an unusually low resistance, an L-E fault would not cause an OPD to operate. There is now a risk of electric shock to a person coming in contact with L whilst also in some continuity with true earth but, if the current through the person exceeds 30 mA, that should cause the RCD to operate in the normal way. If the resistance from the person to true earth and/or the resistance of the earth electrode is too high for 30 mA to flow through the person, then the RCD will not operate (just as no RCD would operate with <30 mA flowing though a person from L to E). There is still, of course, no protection for anyone who touches both L & N.

So what is actually gained by having the earthing, and why is the quality (lowness of resistance) of the earthing considered to be so important? In other words, what am I missing?

Kind Regards, John.

 

[Emvee]

But I agree with ericmark the biggest problem is installing and testing your earth rod. Earth rods REALLY need to be testied (this is NOT merely a CYA test, the resistance of an earth rod can be rather unpredicatable).

I must be missing something, because I have always had difficulty in understanding a lot of what I read and hear about generator supplies, so I'd be grateful for some education.

Consider the simple situation in which a generator is to be used only for the local supply (say, to outbuildings) with no interaction with any mains-supplied installation. Also, in the first instance, assume that there is no earthing (i.e. no earth rod).

If the L&N outputs of the generator feed all the loads via an RCD and all loads are supplied with a CPC connected directly to the generator's neutral (not via RCD), then the RCD will operate in response to any L-CPC fault and (if the circuit is loaded) probably any N-CPC fault. If the generator (and circuit) are actually 'insulated' from earth (i.e. the whole supply is floating) then there is theoretically no risk to anyone who touches an L conductor, even if the person is in contact with true earth. As always, there is no protection for a person who touches both L&N, regardless of whether or not they are earthed.

Now introduce an unintentional (genny standing on soil, and its N connected to frame) or intentional (earth rod) connection from the generator's N to true earth. What is now different? The RCD will still operate in response to L-CPC and (usually) N-CPC faults. Unless the earth rod had an unusually low resistance, an L-E fault would not cause an OPD to operate. There is now a risk of electric shock to a person coming in contact with L whilst also in some continuity with true earth but, if the current through the person exceeds 30 mA, that should cause the RCD to operate in the normal way. If the resistance from the person to true earth and/or the resistance of the earth electrode is too high for 30 mA to flow through the person, then the RCD will not operate (just as no RCD would operate with <30 mA flowing though a person from L to E). There is still, of course, no protection for anyone who touches both L & N.

So what is actually gained by having the earthing, and why is the quality (lowness of resistance) of the earthing considered to be so important? In other words, what am I missing?

Kind Regards, John.

John thanks for bringing some reason to this thread.

My intention was to put in earth rods and connect these to the earth spurs on my sockets and light fittings, and these would be connected back to the earth terminal on the consumer unit and I was expecting that this would provide enough protection via the built in RCD. In reality I am only using power tools that are double insulated and plastic light fittings and switches. It is highly unlikely that any livestock will come into contact with any electrical equipment at all. Is this so incredibly dangerous and irresponsible?

I realise that this must horrify qualified electricians who are trained to do things in certain ways, particularly in the risk averse culture that exists around the H&S industry, and that this is why people get upset, but surely there is a common sense approach to this which would be reasonably safe given that precautions would be taken and unnecessary risks avoided.

 

[JohnW2]

John thanks for bringing some reason to this thread.

Well, as I said, since my reasoning seems to fly in the face of much of what is written and said on this subject, I feel that I must be missing something - in which case you may be missing it as well!

No-one else has yet responded to my cry for education but, if someone does, maybe it will become clearer what, if anything, we are missing.

Kind Regards, John.