Concealed Earth clamps

[mrbenn]

Hi,

I'm a self builder (kind of by accident and no choice, since I lost my job due to a stroke last year during a house build) and I'm wiring the house myself, although as is often argued in cases like mine, I worked in telecoms and I'm a practicing Radio Amateur, so electrical theory is not alien to me. Anyway, we don't have the money to pay for an electrician, never mind brickies and chippies, so we went down the inspection by Building Control route (in our case, a large local electrical contractors)

I had the first fix checked with no major problems, but I forgot to ask about connecting up the earth's. As our house is served with a PME shared earth, I have opted to bond all propane and water pipes with 16mm cable to be safe, and I have it all connected now, nice neat and exposed, apart from the two concealed showers. In both cases, I can connect an earth in the loft as it comes up the partition wall, about a meter above the concealed fitting. The problem is that the routing of the hot water copper pipe, comes up from below, i.e. in the ground floor ceiling void. This means that earth bonding the hot water pipe is not possible unless it is concealed. I had thought about using the solder on earth crimp fittings, and solder everything and leave it in the wall. How does this sit with the regs? I can't see a way round it unfortunately. Upstairs has wet underfloor heating, with a screed, so there is no option of having access through floor boards, and the bathrooms are sealed wet rooms, so access to pipe work, even if I could reroute it, is not possible. I guess the only thing I could do is run a hot water pipe into the loft, but that is such a job, I'd rather not if I could help it.

Ideas?

Thanks,

Sean.

 

[telectrix]

why do you want to bond hot water pipes? the only bonds you should need are to the incoming services, and that is only required if they come in in metal pipes.

 

[mrbenn]

why do you want to bond hot water pipes? the only bonds you should need are to the incoming services, and that is only required if they come in in metal pipes.

This is was at question I posed to the inspector during first fix inspection. The incoming water main is MDPE plastic pipe, but he wanted bonding as close to the start of the copper section as possible, and then all pipes bonding. Is not not necessary to bond hot water pipes? All the internal plumbing is copper.

 

[mrbenn]

Propane for kitchen hob. There will be a propane gas hob in the kitchen, supplied by the 47kg red portable propane bottles. At the moment the copper pipe which is routed through the wall, and not into the ground at any point, has its own main earth bond in 16mm back to the main earth block. The guy that inspected the first fix said this needed to be installed, however I'm still unsure, as there is no copper pipe running into the ground, and there should be no way that the metal work would be extraneous, as the bottle would be separated by a rubber hose from said copper pipe.

I have installed all main and supplementary bonding in 16mm as a precaution as we have a pme shared earth, is this necessary? I asked the guy inspecting, and he said it didn't make a difference, although Scottishpower who run the infrastructure told me it is more critical as the earth could theoretically be shared with other properties in the vicinity? With this potential in mind, is unnecessary bonding creating the potential for more harm than good?

 

[mrbenn]

why do you want to bond hot water pipes? the only bonds you should need are to the incoming services, and that is only required if they come in in metal pipes.

Researching this to the n'th degree, most people agree that supplementary bonding is not required if an RCD protects the circuit, however the document linked below suggests otherwise, as did the guy who inspected the first fix installation.

Earth Bonding - Plastic Pipes Group

Achieving cross bonding for the hot and cold feeds of the shower is going to be incredibly difficult to achieve in this case, unless this is done next to the water tank, a few meters away.

 

[telectrix]

forget cross bonding. just test any suspect pipework with an IR test back to the MET. if it is >22k ohms, then forget it.

 

[mrbenn]

I take it I have to remove the water main bond from the MET first?

 

[mrbenn]

I've just done an IR test to the MET using a 500v test on the megger, and with or without the main earth bond to all pipework is 0megohms, I guess the underfloor heating pumps are earthing it all as I have no other obvious routes to earth in the system?
There is solid fuel water heating connected to a stainless steel tank, so all copper pipes will connect to all other copper pipes directly or indirectly via this tank.

 

[telectrix]

so then all your bonding is done through the pipework.