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#137089 - 05/27/03 09:49 PM UK Building Site 120V Equipment  
Hutch  Offline
Joined: May 2002
Posts: 381
South Oxfordshire, UK
I understand it is now a legal requirement for tools/mobile equipment sold in the UK to have a BS 3-square pin plug fitted but what about 120V equipment for use on building sites? What kind of plug will they have fitted – are they all those yellow international standard (IEC?) ones?

How long has this low voltage system been around? – I saw the portable transformer units on my last visit over and saw a cheap solution to a workshop full of US power tools, were I ever to have to return to the UK. During my time working the British building sites/house remodeling as a lowly youth in the mid to late 1970’s about the only electric thing we had was drill and that plugged into a standard socket.

Is the building site system a center-tapped grounded one with 60V on each pin (a la US 240V), or 120V phase to ground, or even isolated?

Are standard NEMA plugs ever used in this system?

Does anywhere else in the 230V phase-to-ground world use this system? – I never came across it in South Africa where an earth leakage unit feeding standard sockets was the only requirement for ‘outside’ work.

Sorry, so many questions.

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#137090 - 05/28/03 04:08 AM Re: UK Building Site 120V Equipment  
djk  Offline
Joined: Dec 2002
Posts: 1,237
The 110V (Not 120V) supplies used on construction sites in the UK are actually governed by a series of EU safety directives.

The transformers are isolated and center tapped with 55V to earth on each side and appliences are connected using yellow CeeForm plugs.

220-230 (or 240)V is completely illegal for handheld use on building sites or in any similar hazardous work areas. Using it in Ireland would be a very serious breech of Health and Safety regulations and the HSA (Health and Safety Athority) could potentially shut a site for such an infraction.

Most hired powertools are also 110V systems.

It should be extended to garden equipment too in my opinion. RCDs are only a partial sollution.

Here's a list of voltage regulations for sites:

Other "Extra low" voltages are required for things like hand lamps etc.

As for your US equipment. It should be ok if:

1) its ok with 110V-120V at 50Hz rather than 60Hz.

and 2) Arn't US outlets are 110V to ground not two 55V to ground centre tapped?

I though the centre tapped stuff applied to the 220V outlets? Where you've 2 110V hots taken from the centre tapped transformer giving you 220V(ish)

NEMA plugs are not used and wouldn't not be allowed as they do not conform with EN (Euro standards) or BS. The system is also only used in hazardous heavy use areas so standard NEMA would be unacceptable.

I've seen situations where people have installed hardwired 110V transformers to feed US equipment here where people had moved to Ireland and generally because NEMA fittings are simply unavailable they just used non-standard UK fittings. (smaller BS 546 in one case and BS1363 with keyed pins in another, I could see the fuse being a problem though if it was a high wattage applience/peaky applience..) It was just for audio equipment and both systems worked fine, actually they said better then NEMA. No sparking!

Fit yellow CeeForm plugs to your powertools. They're a MUCH safer more robust option and will plug directly into a transformer and only cost around £1 each

[This message has been edited by djk (edited 05-28-2003).]

#137091 - 05/28/03 11:12 AM Re: UK Building Site 120V Equipment  
Texas_Ranger  Offline
Joined: Dec 2001
Posts: 2,399
Vienna, Austria
220-230 (or 240)V is completely illegal for handheld use on building sites or in any similar hazardous work areas.

EU directive?????????? In Austria all sites tools are and have always been 220V (handheld) and 380V (all alrger stuff). All temporary site power distribution boards have a nice set of Schuko outlets and red CEE outlets. GFI protection required. (In Germany 300mA, don't know about Austria, probably less, we've always been stricter concerning GFIs than the Germans) Work sites don't even use blue CEE plugs here, just plain tough rubber plugs (IP44). Tough rubber sheathed cords requires for site use. (Not taken too serious, most companies, especially the lighter works, just use DIY grade cords anyway and don't care much about damaged cords, a few years ago our attic was set on fire by a damaged cord the floor guys had used, just twisted and poorly taped splices. Masons and other rough work guys usually have real construction grade cords in good shape though. Floor guys are notoriously bad, I've seen some of them use the cheapest household grade cords but treating them like they had rubber plugs, with all brokjen plugs patched with masking tape (consists mostly of paper). A renovation company once tapped into our basement lights in order to run their drill. Others often wrap their wires around the load side screwshell of the 20A Diazed main fuses)

#137092 - 05/28/03 11:34 AM Re: UK Building Site 120V Equipment  
SvenNYC  Offline
Joined: Aug 2002
Posts: 1,691
New York City
2) Arn't US outlets are 110V to ground not two 55V to ground centre tapped?

To see if I understand correctly:

This 110 volt system is basically

50 -- 0 -- 50


So it's hot on both ends?

This seems similar to USA 240 volt services for airconditioners and some hot water heaters:

120 -- 0 -- 120

where you get 240 volts across the two hot conductors.


#137093 - 05/28/03 06:15 PM Re: UK Building Site 120V Equipment  
lyledunn  Offline
Joined: Jun 2002
Posts: 159
Actually there is no legal requirement to use 110v ct on construction sites. HSE recommend it, BS7671 stipulates it for certain items but there is no legal requirement. Mind you I wouldnt like to be trying to defend a court case brought where 230v was used where 110ct was recommended!


lyle dunn

#137094 - 05/28/03 07:24 PM Re: UK Building Site 120V Equipment  
djk  Offline
Joined: Dec 2002
Posts: 1,237
I'm pretty sure that there is at the very least EU guidelines on this issue. How they're implemented in different parts of the EU is up to the athorities in each country. Generally electrical regulations and construction safety regulations are taken extremely seriously here though.

The penalties for breeching any construction regs in Ireland are enormous. Sites of all scales are subject to random HSA (Health & Safety Athority) inspections. Any breeches = all work stops entirely at the contractors expense. On a large scale site this is a huge incentive to keep things tightly controlled. The customer may implement all sorts of penalty clauses if the contractor causes delays. Low voltage gear, just like hardhats and safety equipment, is required by HSA regulations failure to use it is illegal here and you would also leave yourself wide open to massive law suits if anyone was injured/shocked.

Pretty specific in the legislation: (See paragraph 2)

From "Safety, Health and Welfare at Work (General Application) Regulations 1993" (Ireland)

"41. Portable Equipment

(1) A circuit supplying portable equipment or a socket outlet intended to supply such portable equipment and in which alternating current at a voltage exceeding 125 volts and not exceeding 1,000 volts is used, shall be protected by one or more residual current devices having a tripping current not exceeding 30 milliamperes.

(2) Portable equipment (other than portable transformers and portable generators) supplied at a voltage exceeding 125 volts alternating current shall NOT be used in building operations, works of engineering construction or in damp or confined locations unless its rating exceeds 2 kilovolt amperes.

(3) Portable handlamps supplied at a voltage exceeding 25 volts alternating current or 50 volts direct current shall not be used in building operations, works of engineering construction, damp or confined locations.

(4) Where a transformer is used to supply electricity to - portable equipment at a voltage not exceeding 125 volts alternating current, or a portable handlamp at a voltage not exceeding 25 volts alternating current and in accordance with paragraph (3),

It shall be of the double wound type and the centre point of the lower voltage or secondary winding shall be connected to earth. "

[This message has been edited by djk (edited 05-28-2003).]

#137095 - 05/28/03 10:22 PM Re: UK Building Site 120V Equipment  
Bjarney  Offline
Joined: Apr 2002
Posts: 2,527
West-Southern Inner-Northeast ...
I have read about power tools somewhere in the Europe area requiring (on construction sites?) local-transformer-isolated portable-tool 110V [described as 55-0-55 volt or roughly 110/64-volt wye.]

Note that pin-and-sleeve connectors are generally very rugged and very safe with integral shrouding and tough non-metallic cases. The standard IEC standard 309 “series 1” devices are for European-standards voltages AND IEC standard 309 “series 2” devices are intended for North-American voltages.

[C-H had a good writeup of IEC-309 devices at ]

#137096 - 05/29/03 11:28 AM Re: UK Building Site 120V Equipment  
C-H  Offline
Joined: Sep 2002
Posts: 1,497
Stockholm, Sweden
It seems Ireland is much tougher on that safety thing. In Sweden, construction business has a bad reputation, as it - alongside bars and restaurants - it's the place for shady business. This sometimes reflects onto safety and health. There have e.g. been complaints that is little or no control over the chemicals used. (Not as in not locked in, but as in "I didn't know that could kill you")

The wiring consists of 400V CEE and 230V Schuko extension cords run all over the place. These days RCD's are often used and I don't think there are very many accidents.

[This message has been edited by C-H (edited 05-29-2003).]

#137097 - 05/29/03 06:03 PM Re: UK Building Site 120V Equipment  
lyledunn  Offline
Joined: Jun 2002
Posts: 159
Your post is very interesting. It would seem that Ireland (south) has adopted into law many non-statutory recommendations from BS7671.


lyle dunn

#137098 - 05/29/03 07:09 PM Re: UK Building Site 120V Equipment  
David UK  Offline
Joined: Oct 2002
Posts: 134
Inverness, Scotland
As far as I am aware the use of 110V CTE in British (& Irish) construction sites is a localised (UK) practice, nothing to do with EU directives.
I think the use of 110V CTE started in the late 70's, before 30mA RCD's were in common use in the UK.
I can remember seeing 110V sockets & power tools in my school's technical workshops, that was back in the late 70's. So I expect the use of 110V power tools may have started before that, & was certainly the norm by the time I entered the electrical trade in 1982.

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