Btw, these are cheapo Artec Hotrails (which actually sound really good). Googling about a bit, I see that other people have found the same thing with this pickup, so maybe it's how they are...  
I've just installed a Hotrails-type pickup in the bridge position on my Strat copy. I followed the wiring instructions that came with the pickup (green = live, black+bare = ground, red+white = for split so tape off) and the pickup works fine, no noise issues when in use. However, if I touch either or both of the pickup rails then I get a buzz, the same type of buzz you get when you touch a guitar lead jack when the other end of the lead is plugged into an amp.

I've never used this type of pickup before and (maybe a stupid question but) wanted to know if this is normal or if there could be some grounding issue causing this? (I've already double checked the wiring btw).

Thanks for any advice.
I might give shielding the pickup cavity a try, but tbh I'm doubting it will make much difference as the interference has affected similarly four different guitars I've tried with single coils.
2Crosser On a previous guitar I had I insulated the cavity with copper foil but unfortunately it didn't seem to make any difference at all.
dspellman Thanks for the reply. Would there be any way to block this type of interference, or at least reduce it?
Whenever the central heating system is on in the house where I live, it causes a buzzing type interference when using single coil pickups. The noise is negligible with humbuckers, but with single coils it is very noticeable and annoying. I have tried different guitars and different amps (both solid state and tube) with the same result. I can also hear it when plugged straight into a BOSS BR80 recorder. I can minimize the noise slightly by holding the guitar in a certain direction. 

I don't know anything about the technical aspects of the heating system (nor does anyone else who lives here). It was installed a year or so ago and switches on automatically at certain times, mainly at night. This interference only seems to occur when it is on.

Does anyone know what could be the cause of this interference and how I might be able to stop it?

Thanks for any help.
I have a P90 pickup with a single conductor braided shield wire. If I touch the braided wire with one probe of my multimeter, and the inner wire with the other probe, the multimeter shows the pickup's resistance (this is without it being connected to the guitar).

Might be a stupid question the above what should happen?

Thanks for the replies. My reason for wanting to use two amps with the loop pedal is due to what fly135 has mentioned.
Thanks, that's been very helpful.  
I have a looper pedal, two small combo amps and an ABY box.

With this equipment (or something similar) is there any way I could do the following without unplugging/replugging guitar cables:

Create a loop using one of the amps, then while it plays back through that amp play over the top of it through the other amp?

Thanks for any help.
My practice amp is a Bugera V5 infinium, stock tubes replaced with some nicer sounding ones. Good for clean tones but even cranked up not much overdrive going on.
The typical gain/overdrive/distortion that you can get with a Marshall amp, is there any pedal (made by Marshall or anyone else) with which you can get that sound? I've been looking for something like this but all I can find is either unpleasant fuzz, lame/weak overdrive or harsh metal. Basically I'm looking for a nice Marshall-type distortion in a pedal.
Update: I've filed down the string slot on the bridge and the height is just as I wanted it now. Intonation still seems fine so I'm pleased with the result.
Thanks very much for the info. Having checked those images my bridge is of the plain 3rd variety (and I use a plain 3rd). The string just seems too high to me, even taking into consideration the curve design. At the 12th fret the action is higher on the 3rd string than it is on the 4th. I think I'll try and file down the slot and see how it goes. It's only a cheapo guitar so I can easily replace the bridge if it doesn't turn out well.
Thanks for the reply but my question was about filing down an individual saddle on the bridge, rather than doing anything with the nut. A wraparound bridge with adjustable intonation AND individual string height would be ideal, but I'm not sure if such a thing exists.
On my LP Junior-style guitar I can set the action pretty low just by screwing the studs down on the wraparound bridge. However, the G-string always seems too high in comparison to the other strings. I'd like to lower it slightly by filing down its slot in the bridge. Does anyone know what would be the best tool to use for doing this? Preferably something I might already have or can buy cheap (i.e. not from Stewmac, etc).
I eventually resoldered everything and it seems to be fine now. Looks like it was a ground issue.
Also, is there any actual difference between flipping the magnet and swapping around the green/black wires? Thanks btw!
Haven't got around to putting everything back how it was yet, but (after Googling about a bit) I've tested the ground with a multimeter from the strings to the output socket nut and get a 0 reading, which apparently means that the grounding is okay. However, if I go from individual pole pieces (of either pickup) to the output socket nut, some of them give me a 0 reading and others don't make the meter move at all. Is this normal?
I was super careful when removing the magnet and made sure not to touch anything else so I'm sure it's not that. I've resoldered all the earth wires on the selector switch earth prong, insulated everything with tape and still the buzz is there :/. I haven't installed the pickup properly yet with the mount and everything (and I'll need to get some new tape for it too) so I'm just testing it with it loose in the cavity, but I can't see how that would make much difference. Not sure what to do now apart from completely removing the selector switch again and resoldering everything, and I'm running out of wire length.
Quote by H4T3BR33D3R
Just make sure when youre pushing the magnet through that you arent breaking any connections on the pickup and make sure you mark the original orientation so you know which way to flip.

Managed to do that okay and the output isn't quieter when in the middle position anymore, but now there seems to be a different issue. The bridge pickup is a bit hummy and when I touch one of the pole pieces (especially an outer one) it buzzes. If I touch one while I have my thumb on the tail piece it doesn't buzz. This doesn't happen with the neck pickup. Is this likely to be a grounding issue or something else?
Thanks a lot for the reply. I will try flipping the magnet (I didn't know you could do this) as it saves me the hassle of some tricky resoldering.
I have a dual humbucker electric guitar with one volume knob, one tone knob and a 3-way selector switch. I decided to change the bridge pickup (a TJ Jones Ltd, as is the neck one) for a Seymour Duncan SH-4 JB.

After removing the old bridge pickup, I connected the new one in the same way (i.e. to the selector switch) following the wiring guide on the Seymour Duncan website: black = live; green + bare = solder together for earth; red + white = solder together and tape off.

After doing this and testing the new pickup I immediately noticed that the output was quieter when the the selector switch was in the middle position. After Googling this issue it seems that the pickups are "out of phase". I don't know if this is due to the two pickups being of different brands (note: on the TJ Jones pickup the white wire is the live one), or if there is some other reason for this.

I'm guessing I need to connect the wires from the Seymour Duncan pickup in a different way, but I'm not sure exactly how. I was wondering if anyone could give me some advice on how to fix this.